Histological and Histochemical Studies on the Esophagus, Stomach and Small Intestines of Vara- Nus Niloticus

Varanus niloticus Ahmed et al. Histological and Histochemical Studies on the Esophagus, Stomach and Small Intestines of Vara- nus niloticus

Ahmed YA1, El-Hafez AAE2, Zayed AE2

1 Faculty of Veterinary Science, South Valley University, Qena, Egypt. 2 21 22 Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt. Email: [email protected]

______With 4 figures Received June 2009; accepted for publication October 2009

Abstract The folded esophageal mucosa had ciliated columnar epithelium with muc- Information on the digestive system of ous secreting goblet cells, which the reptiles is based on relatively few stained positive with PAS and AB. studies on some of the now present 7500 reptilian species. Yet, the gap The esophageal mucosa was folded between our understanding of the major and the lining epithelium was ciliated columnar epithelium with mucous se- 23 24 similarities and / or differences between creting goblet cells, which stained posi- the mammalian and reptilian digestive system does not seem satisfiable. The tive with PAS and AB. Fig (21): A photomicrograph of dog liver showing intensive positive reaction to acid aim of the current study was to investi- The stomach was divided into fundic phosphatase in A- group (II) and B- group (III). Stain: Gomori's lead method. gate the morphological structure of one and pyloric regions. The mucosa was of the most common reptilian species in thrown into gastric pits, into which the Fig (22): A photomicrograph of dog liver showing intensive positive reaction to alkaline Egypt, Varanus niloticus or Nile moni- gastric glands opened. The surface phosphatase in A- group (II) and B- group (III). Stain: Calcium cobalt method. tor. Specimens for histological exami- epithelium was mucous secreting co- nation were collected from the esopha- Fig (23): A photomicrograph of dog liver showing intensive positive reaction to ATPase lumnar cells and stained positive with geus, stomach and small intestine of in A- group (II) and B- group (III). Stain: Modified method. PAS but negative with AB. The fundic the Nile monitor and pro-cessed for pa- gland was made by oxynticopeptic cells raffin embedding. Sections were Fig (24): A photomicrograph of dog liver showing intensive positive reaction to in A- and few mucous cells, while the entire stained with haemat-oxylin and eosin group (II) and B- group (III). Stain: Nitro-blue tetrazolium (NBT) method. pyloric gland was made by mucous for general morpho-logy. Periodic Acid cells stained positive for both PAS and Schiff's (PAS) and Alcian Blue (AB) AB. The small intestine showed many staining methods were applied to detect villi but occasional poorly developed the different types of the mucous con- intestinal crypts were. The intestinal tents of the gastro-intestinal tract. mucosa was lined with absorptive co- Some paraffin sections were stained lumnar epithelium with goblet cells, with Grimelius silver impregnation tech- which stained positive with PAS and nique for localization of the enteroendo- AB. Enteroendocrine cells were of dif- crine cells. ferent shapes; rounded, spindle, oval or J. Vet. Anat. 35 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. pyramidal and were localized in the sur- like head, sharp claws, and a long and formed of folds lined by ciliated colum- The reptilian small intestine may be face epithelium of the esophagus and strong tail, which is used to defend itself nar epithelium with goblet cells. Some highly convoluted as in turtles or rela- small intestine, and among the cells of when threatened (Alden et al., 2005). snakes have mucous glands along their tively straight as in snakes (Parsons the gastric glands. This species of reptiles used to eat any submucosa (Elliott, 2007). The muscu- and Cameron, 1977). The intestinal thing it can overpower or find as a car- laris mucosa of the esophagus is ab- surface is varies among different This is the first report about the histolo- rion such as arthropods, frogs, fish, sent in many species of reptiles but may groups; it may be thrown into longit- gy of the alimentary tract of the Varanus birds, small mammals and other smaller be found in some species of turtles udinal and transverse folds, have a zig- niloticus. Further studies are required reptiles as well as the eggs of the Nile (Elliott, 2007). zag pattern or netlike or honeycomb for investigation the possibility of using crocodiles (Capula, 1990; Smith et al., appearance, or consists of fine stria- this animal as a model for studying the 2008 ). Depending upon its powerful In reptiles the stomach varies in shape tions (Parsons and Cameron, 1977). regulation of the digestive processes as tail, the Nile monitor is an excellent (Elliott, 2007). The stomach of turtles The mucosa is organized into villi with well as to understand the theory of de- swimmer and it can stay under the wa- has greater and lesser curvatures, cro- poorly developed intestinal crypts in velopment. ter for up to one hour (Capula, 1990), codiles have a saccular stomach, li- most species or crypts maybe absent how-ever, it is not only an aquatic ani- zards have an ovoid one, while the (Luppa, 1 977). The lining epithelium of Key words: mal, but also walks and sometimes stomach of snakes is elongated in the small intestine is formed of absorp- climbs trees to feed, bask or sleep (Al- shape (Madrid et al., 1989). The muco- tive columnar cells and goblet cells. Reptiles, Varanus niloticus , Alimentary den et al., 2005). Mating of the Nile sa of the stomach is folded and the ex- Enteroendocrine cells can be identified Tract, Morphology monitors occurs after rainy seasons, tend of folding varies among different using Grimelius silver stain (Burrell et groups of reptiles. Two parts of the rep- Introduction and the female give about 60 eggs that al., 1992). Beyond the duodenum, it is are incubated for a period of 6-9 months tilian stomach are usually distinguisha- difficult to distinguish between different ble, the fundus and the pylorus (Luppa, It has been suggested that reptiles before hatching, and the offspring reach parts of the small intestine. 1977). The mucosa of the fundic region could serve as a model” Reptiles have their maturity after about 4 years (Ca- consists of rows of branched tubular been suggested to be a future useful pula, 1990). Materials and Methods glands. Each gland consists of a gas- model for studying the physiological The digestive system of the reptiles tric pit and glandular body. Mucous Sample Collection and Paraffin Em- regulation of the digestive process as contains all the structures present in neck cells similar to that of mammals bedding they have well responses to feeding other higher vertebrates, from the oral may be present in some species such An adult female Nile monitor, 1.5 me- even more than other commonly used cavity to the cloaca. The oral cavity is as snakes or absent in others such as ters long was collected from a lake in experimental mammals such as mice, lined by mucous membrane made by turtles (Elliott, 2007). The glandular Qena close to the Nile River. The ani- rats, rabbit and pigs (Secor and Di- non-keratinized stratified squamous portion contains either one type or two mal was killed and the alimentary tract amond, 1998). Reptiles include as epithetlium with salivary glands distrib- types of cells; dark serous (oxyntico- was removed, opened, cleaned and many as 7500 different species, most uted in the submucosa (Putterill and peptic) and clear mucous cells. The samples were taken from the esopha- known are; alligators, turtles, tortoises, Soley, 2003). ratio of the two cells also may be differ- gus, stomach (fundic and pyloric re- lizards and snakes (Elliott, 2007). ent from species to another (Suganuma gions) and different parts of the small The alimentary tract of reptiles is similar One of these reptiles is the Varanus et al., 1981). The dark cells functions intestine. Samples were thoroughly to higher vertebrates with some excep- niloticus or the Nile monitor, which is as both parietal and chief cells of washed in phosphate buffered saline tions. The esophagus shows adaptive the biggest African lizard and one of the mammals. Additional cells, enteroen- and rapidly immersed in either 10% pa- modifications from group to group. In most voracious predators (Capula, docrine cells are scat-tered throughout raformaldehyde for at least 3 days or turtles, the esophagus has heavily kera- 1990). It lives along the Nile; it has the digestive tract. These cells contain Bouin’s fixative for 30 minutes. The tinized papillae that protect the mucosa been found mainly in swamps and lakes mem-braned vesicles of peptide hor- samples were dehydrated in an ascen- from abrasive diet such as speculated (Smith et al., 2008). Nile monitor has a mones and amines (D'Este et al., ding graded ethanol series (70, 90, 95 sponges and jellyfish, and also may act powerful body with an elongated snake- 1995), and function similar to that of and 100%) for 1 hour each, and then as filtering devices. In lizards, it is mammals (Krause et al., 1985). cleared in 3 changes of, xylene for 24 J. Vet. Anat. 36 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. pyramidal and were localized in the sur- like head, sharp claws, and a long and formed of folds lined by ciliated colum- The reptilian small intestine may be face epithelium of the esophagus and strong tail, which is used to defend itself nar epithelium with goblet cells. Some highly convoluted as in turtles or rela- small intestine, and among the cells of when threatened (Alden et al., 2005). snakes have mucous glands along their tively straight as in snakes (Parsons the gastric glands. This species of reptiles used to eat any submucosa (Elliott, 2007). The muscu- and Cameron, 1977). The intestinal thing it can overpower or find as a car- laris mucosa of the esophagus is ab- surface is varies among different This is the first report about the histolo- rion such as arthropods, frogs, fish, sent in many species of reptiles but may groups; it may be thrown into longit- gy of the alimentary tract of the Varanus birds, small mammals and other smaller be found in some species of turtles udinal and transverse folds, have a zig- niloticus. Further studies are required reptiles as well as the eggs of the Nile (Elliott, 2007). zag pattern or netlike or honeycomb for investigation the possibility of using crocodiles (Capula, 1990; Smith et al., appearance, or consists of fine stria- this animal as a model for studying the 2008 ). Depending upon its powerful In reptiles the stomach varies in shape tions (Parsons and Cameron, 1977). regulation of the digestive processes as tail, the Nile monitor is an excellent (Elliott, 2007). The stomach of turtles The mucosa is organized into villi with well as to understand the theory of de- swimmer and it can stay under the wa- has greater and lesser curvatures, cro- poorly developed intestinal crypts in velopment. ter for up to one hour (Capula, 1990), codiles have a saccular stomach, li- most species or crypts maybe absent how-ever, it is not only an aquatic ani- zards have an ovoid one, while the (Luppa, 1 977). The lining epithelium of Key words: mal, but also walks and sometimes stomach of snakes is elongated in the small intestine is formed of absorp- climbs trees to feed, bask or sleep (Al- shape (Madrid et al., 1989). The muco- tive columnar cells and goblet cells. Reptiles, Varanus niloticus , Alimentary den et al., 2005). Mating of the Nile sa of the stomach is folded and the ex- Enteroendocrine cells can be identified Tract, Morphology monitors occurs after rainy seasons, tend of folding varies among different using Grimelius silver stain (Burrell et groups of reptiles. Two parts of the rep- Introduction and the female give about 60 eggs that al., 1992). Beyond the duodenum, it is are incubated for a period of 6-9 months tilian stomach are usually distinguisha- difficult to distinguish between different ble, the fundus and the pylorus (Luppa, It has been suggested that reptiles before hatching, and the offspring reach parts of the small intestine. 1977). The mucosa of the fundic region could serve as a model” Reptiles have their maturity after about 4 years (Ca- consists of rows of branched tubular been suggested to be a future useful pula, 1990). Materials and Methods glands. Each gland consists of a gas- model for studying the physiological The digestive system of the reptiles tric pit and glandular body. Mucous Sample Collection and Paraffin Em- regulation of the digestive process as contains all the structures present in neck cells similar to that of mammals bedding they have well responses to feeding other higher vertebrates, from the oral may be present in some species such An adult female Nile monitor, 1.5 me- even more than other commonly used cavity to the cloaca. The oral cavity is as snakes or absent in others such as ters long was collected from a lake in experimental mammals such as mice, lined by mucous membrane made by turtles (Elliott, 2007). The glandular Qena close to the Nile River. The ani- rats, rabbit and pigs (Secor and Di- non-keratinized stratified squamous portion contains either one type or two mal was killed and the alimentary tract amond, 1998). Reptiles include as epithetlium with salivary glands distrib- types of cells; dark serous (oxyntico- was removed, opened, cleaned and many as 7500 different species, most uted in the submucosa (Putterill and peptic) and clear mucous cells. The samples were taken from the esopha- known are; alligators, turtles, tortoises, Soley, 2003). ratio of the two cells also may be differ- gus, stomach (fundic and pyloric re- lizards and snakes (Elliott, 2007). ent from species to another (Suganuma gions) and different parts of the small The alimentary tract of reptiles is similar One of these reptiles is the Varanus et al., 1981). The dark cells functions intestine. Samples were thoroughly to higher vertebrates with some excep- niloticus or the Nile monitor, which is as both parietal and chief cells of washed in phosphate buffered saline tions. The esophagus shows adaptive the biggest African lizard and one of the mammals. Additional cells, enteroen- and rapidly immersed in either 10% pa- modifications from group to group. In most voracious predators (Capula, docrine cells are scat-tered throughout raformaldehyde for at least 3 days or turtles, the esophagus has heavily kera- 1990). It lives along the Nile; it has the digestive tract. These cells contain Bouin’s fixative for 30 minutes. The tinized papillae that protect the mucosa been found mainly in swamps and lakes mem-braned vesicles of peptide hor- samples were dehydrated in an ascen- from abrasive diet such as speculated (Smith et al., 2008). Nile monitor has a mones and amines (D'Este et al., ding graded ethanol series (70, 90, 95 sponges and jellyfish, and also may act powerful body with an elongated snake- 1995), and function similar to that of and 100%) for 1 hour each, and then as filtering devices. In lizards, it is mammals (Krause et al., 1985). cleared in 3 changes of, xylene for 24 J. Vet. Anat. 37 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. hours. The cleared specimens were lar in shape and its mucosa thrown into seen among the mucous cells of the Grimelius silver stain was applied on then embedded in melted paraffin wax. longitudinal folds. Histo-logically, the gastric glands in both parts. Lamina the paraffin sections to localize the en- stomach divided into two distinct parts; propria of fundic and pyloric region was teroendocrine cells. Enteroendocrine Histological staining the fundus or body and the pylorus loose connective tissue with many lym- cells were oval or spindle in shape and Paraffin embedded specimens were (Figs. 1B, C). The stomach was lined phocytes and eosinophils. The sub- found in all parts of the alimentary tract sectioned at 6 µm thickness using a through its length with mucous- mucosa was connective tissue layer examined (Fig. 4A, B). They were dis- rotary microtome. Sections were de- secreting columnar epithelium that with blood vessels. Underneath the tributed in the surface epithelium of the paraffinized and stained with haemato- showed numerous invaginations, gastric submucosa, the tunica muscularis con- esophagus and intestine (Fig. 4A), xylin and eosin for general morphology. pits, which led to glandular structures, sisted of inner circular and outer longi- where they made contact with the lu- For detection of mucous in the alimen- the gastric glands (Figs. 2C, D). The tudinal smooth muscle cells. The pylor- men via cytoplasmic processes. In the tary tract of the Varanus niloticus , gastric surface epithelium showed the ic region showed well developed layers stomach, they were very few in the sur- sections were stained with periodic acid same histological features in both fundic of smooth muscles (Fig. 1C). face epithelium, but they were seen in Schiff, alcian blue (PAS-AB; pH 2.5) to and pyloric regions, and exhibited abundance within the pyloric glands. In demonstrate the full comple-ment of strong staining with PAS but did not The structure of the small intestine ap- stomach, the enteroendocrine cells ap- tissue proteoglycans; alcian blue (AB) react with AB (Fig. 3B). In the fundic peared uniform throughout its entire peared pyramidal, oval or spindle in stain specifically acidic mucins while region, the epithelium forms deep length. The intestinal mucosa of the shape and made contact with the PAS stain neutral one. Grimelius silver glands, fundic glands. The fundic small intestine folded into villi with no or basement membrane between mucous impregnation tech-nique was used for glands are branched tubular and formed few intestinal crypts (Fig. 2D). It was cells. detection of entero-endocrine (argyro- primarily of dark oxynticopeptic cells difficult to distinguish between different philic) cells. with some clear mucous cells located parts of the small intestine. Two basic Discussion between the gastric pits and fundic types of cells are present in the intes- glands (Fig. 2D). We observed that the tinal lining epithelium; columnar absorp- The aim of this study was to document Results oxynticopeptic cells showed different tive cells and goblet cells that secret the histology of the alimentary tract of a gradient of staining; some cells were both types of the mucinous substances common Egyptian reptilian species, Histological Structure of the Mucosa deeply stained, while, some other cells as indicated by positive reaction to both Varanus niloticus or the Nile monitor. and characterization of the Mucinous appeared granulated or nearly empty. PAS and AB. The epithelium covering Classic special histologic techniques Contents of the Alimentary Tract of The oxynticopeptic cells were cuboidal (epithelium covers the villi surface not were used. the Varanus niloticus or pyramidal in shape and stained lines) the villi was simple columnar with Similar components as in higher verte- deeply acidophilic but they showed dif- goblet cells. No Paneth cells were brates with few exceptions were found The alimentary tract of the Varanus nilo- ferent gradient of staining; some cells seen. The lamina propria was rich in in the alimentary tract of this species. ticus revealed the typical layers seen in were deeply stained, while, some other lymphocytic infil-trations and many eo- The lining epithelium of the esophagus higher vertebrates; mucosa, submuco- cells appeared granulated or nearly sinophils. A not well developed layer of was ciliated columnar cells with mucous sa, tunica muscularis and serosa (Figs. empty.. Oxynticopeptic cells stained circular muscularis mucosa was secreting cells. Although, the lining 1A-D). The esophagus was a short negative with both PAS and AB. The present. The submucosa was extreme- epithelium of the esophagus of some tube and its mucosa was folded (Fig. mucous cells appeared clear or with ly narrow, and the circular and longitu- reptiles is similar to that of mammals; 1A). The esophageal mucosa con- foamy cytoplasm and stained positive dinal layers of the tunica muscularis stratified squamous epithet-lium but it is tained extensive primary and secondary with PAS and AB. The pyloric glands contained distinct layers of dense fibr- also known that some species are dif- folds, and the lining epithelium con- were simple tubular, shorter than those ous connective tissue (Fig. 2D). ferent and lined with columnar epithe- sisted of ciliated colum-nar epithelium in the fundic region and consisted only Localization of Enteroendocrine lium (Elliott, 2007) and that is in agree- and mucous secreting goblet cells of numerous mucosecreting cells, which Cells in the Alimentary Tract of the ment with the result reported here. The (Figs. 2A, B), which stained positive showed positive reaction with PAS and Varanus niloticus mucous secreting cells stained positive with both PAS and AB (Fig. 3A). The AB (Fig. 3C). Mitotic figures were often stomach of Varanus niloticus was sacu- with PAS and AB, suggesting that they

J. Vet. Anat. 38 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. hours. The cleared specimens were lar in shape and its mucosa thrown into seen among the mucous cells of the Grimelius silver stain was applied on then embedded in melted paraffin wax. longitudinal folds. Histo-logically, the gastric glands in both parts. Lamina the paraffin sections to localize the en- stomach divided into two distinct parts; propria of fundic and pyloric region was teroendocrine cells. Enteroendocrine Histological staining the fundus or body and the pylorus loose connective tissue with many lym- cells were oval or spindle in shape and Paraffin embedded specimens were (Figs. 1B, C). The stomach was lined phocytes and eosinophils. The sub- found in all parts of the alimentary tract sectioned at 6 µm thickness using a through its length with mucous- mucosa was connective tissue layer examined (Fig. 4A, B). They were dis- rotary microtome. Sections were de- secreting columnar epithelium that with blood vessels. Underneath the tributed in the surface epithelium of the paraffinized and stained with haemato- showed numerous invaginations, gastric submucosa, the tunica muscularis con- esophagus and intestine (Fig. 4A), xylin and eosin for general morphology. pits, which led to glandular structures, sisted of inner circular and outer longi- where they made contact with the lu- For detection of mucous in the alimen- the gastric glands (Figs. 2C, D). The tudinal smooth muscle cells. The pylor- men via cytoplasmic processes. In the tary tract of the Varanus niloticus , gastric surface epithelium showed the ic region showed well developed layers stomach, they were very few in the sur- sections were stained with periodic acid same histological features in both fundic of smooth muscles (Fig. 1C). face epithelium, but they were seen in Schiff, alcian blue (PAS-AB; pH 2.5) to and pyloric regions, and exhibited abundance within the pyloric glands. In demonstrate the full comple-ment of strong staining with PAS but did not The structure of the small intestine ap- stomach, the enteroendocrine cells ap- tissue proteoglycans; alcian blue (AB) react with AB (Fig. 3B). In the fundic peared uniform throughout its entire peared pyramidal, oval or spindle in stain specifically acidic mucins while region, the epithelium forms deep length. The intestinal mucosa of the shape and made contact with the PAS stain neutral one. Grimelius silver glands, fundic glands. The fundic small intestine folded into villi with no or basement membrane between mucous impregnation tech-nique was used for glands are branched tubular and formed few intestinal crypts (Fig. 2D). It was cells. detection of entero-endocrine (argyro- primarily of dark oxynticopeptic cells difficult to distinguish between different philic) cells. with some clear mucous cells located parts of the small intestine. Two basic Discussion between the gastric pits and fundic types of cells are present in the intes- glands (Fig. 2D). We observed that the tinal lining epithelium; columnar absorp- The aim of this study was to document Results oxynticopeptic cells showed different tive cells and goblet cells that secret the histology of the alimentary tract of a gradient of staining; some cells were both types of the mucinous substances common Egyptian reptilian species, Histological Structure of the Mucosa deeply stained, while, some other cells as indicated by positive reaction to both Varanus niloticus or the Nile monitor. and characterization of the Mucinous appeared granulated or nearly empty. PAS and AB. The epithelium covering Classic special histologic techniques Contents of the Alimentary Tract of The oxynticopeptic cells were cuboidal (epithelium covers the villi surface not were used. the Varanus niloticus or pyramidal in shape and stained lines) the villi was simple columnar with Similar components as in higher verte- deeply acidophilic but they showed dif- goblet cells. No Paneth cells were brates with few exceptions were found The alimentary tract of the Varanus nilo- ferent gradient of staining; some cells seen. The lamina propria was rich in in the alimentary tract of this species. ticus revealed the typical layers seen in were deeply stained, while, some other lymphocytic infil-trations and many eo- The lining epithelium of the esophagus higher vertebrates; mucosa, submuco- cells appeared granulated or nearly sinophils. A not well developed layer of was ciliated columnar cells with mucous sa, tunica muscularis and serosa (Figs. empty.. Oxynticopeptic cells stained circular muscularis mucosa was secreting cells. Although, the lining 1A-D). The esophagus was a short negative with both PAS and AB. The present. The submucosa was extreme- epithelium of the esophagus of some tube and its mucosa was folded (Fig. mucous cells appeared clear or with ly narrow, and the circular and longitu- reptiles is similar to that of mammals; 1A). The esophageal mucosa con- foamy cytoplasm and stained positive dinal layers of the tunica muscularis stratified squamous epithet-lium but it is tained extensive primary and secondary with PAS and AB. The pyloric glands contained distinct layers of dense fibr- also known that some species are dif- folds, and the lining epithelium con- were simple tubular, shorter than those ous connective tissue (Fig. 2D). ferent and lined with columnar epithe- sisted of ciliated colum-nar epithelium in the fundic region and consisted only Localization of Enteroendocrine lium (Elliott, 2007) and that is in agree- and mucous secreting goblet cells of numerous mucosecreting cells, which Cells in the Alimentary Tract of the ment with the result reported here. The (Figs. 2A, B), which stained positive showed positive reaction with PAS and Varanus niloticus mucous secreting cells stained positive with both PAS and AB (Fig. 3A). The AB (Fig. 3C). Mitotic figures were often stomach of Varanus niloticus was sacu- with PAS and AB, suggesting that they

J. Vet. Anat. 39 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. secrete both neutral and acidic muco- At the distal portion of the stomach, lian such as guinea pig, gastric glands muscle fibers. The submucosa is be- substances. The mucous, especially oxynticopeptic cells contain few zymo- (Sato and Spicer, 1980), but different low the muscularis mucosa, followed by the acidic one, which increases the vis- gen granules, numerous mito-chondria from some lizards and crocodiles where the tunica muscularis and then serosa. cosity of the mucous contents may be and a well developed tubule-vesicular the mucous cells secrete only neutral The small intestine histology was gen- important for lubrication the mucosa system typical of the mammalian pa- mucous (Madrid et al., 1989) and other erally typical to crocodiles and lizard and allowing the passage of the large rietal acid-secreting cells (Giraud et al., reptiles such as some species of (Holmberg et al., 2002; Elliott, 2007). food particles, in addition to immobiliza- 1979; Ferri et al., 1999). Thus, it is not snakes in which the mucous cells ela- tion of overcome hunted food such as surprising that oxyn-ticopeptic may ela- borates strong acidic mucosubstances Enteroendocrine cells are another cell arthropods and mice. Also, the mucous borate both hydro-chloric acid pep- (Suganuma et al., 1981). The mucous type found in the alimentary tract of the is important to protect the mucosa from sin0gen synthesized by the parietal and is important to protect the gastric muco- Varanus niloticus and were scattered the sharp objects may reach the eso- chief cells in mammalian stomach (Eu- sa from the effect of hydrochloric acid among the surface epithelium of esophagus such as spiny fish. The pres- rell and Frappier, 2006). It is not unique and pepsin in the fundic region, but in phageal folds and intestinal villi. In ence of both neutral and acidic mucin in to reptiles that one cell type performs the pylorus it may be primarily important stomach, they were located among the the lining epithelium of esophagus is not both functions of parietal and chief cells as lubricant. Mitotic figures were seen glandular epithelium. They were more unique for the Varanus niloticus, but it of mammals. It is also the case in fowl among the glandular mucous cells. numerous in the pyloric gland region was seen in other reptiles (Elliott, 2007) (Selvan et al., 2008) and some fish These cells may act as stem cells for than other locations of the alimentary and fish species (Parillo et al., 2004), (Ota et al., 1998). We observed that different cell type regeneration in the tract. There are very few studies on crocodiles (Uriona et al., 2005) and in the oxyntico-peptic cells showed differ- glandular epithelium. the entero-endocrine cells of the rep- many birds (Selvan et al., 2008). Unlike ent gradient of staining; some cells tiles. In one immunohistochemical the mammalian esophagus (Eurell and were deeply stained, while, some other The structure of the small intestine ap- study, immunereactivity for somato- Frappier, 2006), the muscular layers of cells appeared granulated or nearly peared uniform throughout its entire statin, gastrin, motilin, serotonin, pep- the esophagus of Varanus niloticus is empty. Variation of staining of the length. Two basic types of cells are singen and bovine pancreatic polypep- entirely smooth. Therefore, it may allow oxyntico-peptic cells may due to a se- present in the intestinal lining epithe- tide were detected in the mucosa of the the esophagus to expand and to tole- cretion gradient of hydrochloric acid lium; columnar absorptive cells and alimentary tract of the King’s skink rate the passage of the large food par- and/ or pepsingen, as hydrochloric acid goblet cells that secret both types of the (Arena et al., 1990), and another one ticles such as mice or fish. is essential for the activation of pepsi- mucinous substances as indicated by reported similar results in the gut of nogen. positive reaction to both PAS and AB.” frogs (El-Salhy et al., 1981). In different Similar to other reptiles; King's skink The intestinal crypts were less devel- mammalian species such as rodents (Arena et al., 1990) and lizard (Ferri et The superficial epithelium of the sto- oped. In mammals, proliferative activity and feline parallel results were reported al., 1999), the fundic glands of the stomach showed positive reaction with is confined to the intestinal crypts where (Alumets et al., 1977; Alumets et al., mach of the Varanus niloticus contain- PAS but not with AB. It is likely that, undifferentiated stem cells give rise to 1979; Kitamura et al., 1982a; Kitamura ed only one cell type, oxyntico-peptic this cell layer is responsible for secre- new cells that continually replace those et al., 1982b). These peptides and cells. In some other reptiles such as tion of neutral mucosubstances, and are lost at the tips of each villus (Gilbert, amines known to regulate the different crocodiles it was reported that the mor- that in similar to other reptilian species 1997; Junqueira et al., 1998). It was digestive and motility functions of the phology of the oxyntico-peptic cells (Arena et al., 1990; Ferri and Liquori, not clear using the method reported in alimentary tract (Krause et al., 1985) changes from the proximal to the distal 1992; Ferri and Liquori, 1994; Ferri et this study to know where the stem cells and they are likely to do such in the Va- mucosa of the stomach. At the proxy- al., 1999). While, we found mucous- are located and how the lining epithe- ranus niloticus. This first report on of mal portion of the stomach, the oxynti- secreting cells in the upper part of the lium is replaced in the intestinal tract of the alimentary tract of the Egyptian Va- copeptic cells have characteristic fea- fundic glands and in the whole pyloric the Varanus niloticus. Below the epi- ranus niloticus highlighting the general tures of protein synthesizing cells; well glands elaborate both acidic and neutral thelium is the lamina propria consisting morphology, mucous contents as well developed rough endoplasmic reticulum mucosubstances as they stained posi- of blood vessels and connective tissue. as locations and appearance of the en- and many granules, similar to pepsino- tive for both PAS and AB and that simi- The muscularis mucosa is very thin and docrine cells may be the beginning of gen-secreting chief cells of mammals. lar to mucous neck cells of the mamma- consists of a single layer of smooth more interest in this species. Further J. Vet. Anat. 40 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. secrete both neutral and acidic muco- At the distal portion of the stomach, lian such as guinea pig, gastric glands muscle fibers. The submucosa is be- substances. The mucous, especially oxynticopeptic cells contain few zymo- (Sato and Spicer, 1980), but different low the muscularis mucosa, followed by the acidic one, which increases the vis- gen granules, numerous mito-chondria from some lizards and crocodiles where the tunica muscularis and then serosa. cosity of the mucous contents may be and a well developed tubule-vesicular the mucous cells secrete only neutral The small intestine histology was gen- important for lubrication the mucosa system typical of the mammalian pa- mucous (Madrid et al., 1989) and other erally typical to crocodiles and lizard and allowing the passage of the large rietal acid-secreting cells (Giraud et al., reptiles such as some species of (Holmberg et al., 2002; Elliott, 2007). food particles, in addition to immobiliza- 1979; Ferri et al., 1999). Thus, it is not snakes in which the mucous cells ela- tion of overcome hunted food such as surprising that oxyn-ticopeptic may ela- borates strong acidic mucosubstances Enteroendocrine cells are another cell arthropods and mice. Also, the mucous borate both hydro-chloric acid pep- (Suganuma et al., 1981). The mucous type found in the alimentary tract of the is important to protect the mucosa from sin0gen synthesized by the parietal and is important to protect the gastric muco- Varanus niloticus and were scattered the sharp objects may reach the eso- chief cells in mammalian stomach (Eu- sa from the effect of hydrochloric acid among the surface epithelium of esophagus such as spiny fish. The pres- rell and Frappier, 2006). It is not unique and pepsin in the fundic region, but in phageal folds and intestinal villi. In ence of both neutral and acidic mucin in to reptiles that one cell type performs the pylorus it may be primarily important stomach, they were located among the the lining epithelium of esophagus is not both functions of parietal and chief cells as lubricant. Mitotic figures were seen glandular epithelium. They were more unique for the Varanus niloticus, but it of mammals. It is also the case in fowl among the glandular mucous cells. numerous in the pyloric gland region was seen in other reptiles (Elliott, 2007) (Selvan et al., 2008) and some fish These cells may act as stem cells for than other locations of the alimentary and fish species (Parillo et al., 2004), (Ota et al., 1998). We observed that different cell type regeneration in the tract. There are very few studies on crocodiles (Uriona et al., 2005) and in the oxyntico-peptic cells showed differ- glandular epithelium. the entero-endocrine cells of the rep- many birds (Selvan et al., 2008). Unlike ent gradient of staining; some cells tiles. In one immunohistochemical the mammalian esophagus (Eurell and were deeply stained, while, some other The structure of the small intestine ap- study, immunereactivity for somato- Frappier, 2006), the muscular layers of cells appeared granulated or nearly peared uniform throughout its entire statin, gastrin, motilin, serotonin, pep- the esophagus of Varanus niloticus is empty. Variation of staining of the length. Two basic types of cells are singen and bovine pancreatic polypep- entirely smooth. Therefore, it may allow oxyntico-peptic cells may due to a se- present in the intestinal lining epithe- tide were detected in the mucosa of the the esophagus to expand and to tole- cretion gradient of hydrochloric acid lium; columnar absorptive cells and alimentary tract of the King’s skink rate the passage of the large food par- and/ or pepsingen, as hydrochloric acid goblet cells that secret both types of the (Arena et al., 1990), and another one ticles such as mice or fish. is essential for the activation of pepsi- mucinous substances as indicated by reported similar results in the gut of nogen. positive reaction to both PAS and AB.” frogs (El-Salhy et al., 1981). In different Similar to other reptiles; King's skink The intestinal crypts were less devel- mammalian species such as rodents (Arena et al., 1990) and lizard (Ferri et The superficial epithelium of the sto- oped. In mammals, proliferative activity and feline parallel results were reported al., 1999), the fundic glands of the stomach showed positive reaction with is confined to the intestinal crypts where (Alumets et al., 1977; Alumets et al., mach of the Varanus niloticus contain- PAS but not with AB. It is likely that, undifferentiated stem cells give rise to 1979; Kitamura et al., 1982a; Kitamura ed only one cell type, oxyntico-peptic this cell layer is responsible for secre- new cells that continually replace those et al., 1982b). These peptides and cells. In some other reptiles such as tion of neutral mucosubstances, and are lost at the tips of each villus (Gilbert, amines known to regulate the different crocodiles it was reported that the mor- that in similar to other reptilian species 1997; Junqueira et al., 1998). It was digestive and motility functions of the phology of the oxyntico-peptic cells (Arena et al., 1990; Ferri and Liquori, not clear using the method reported in alimentary tract (Krause et al., 1985) changes from the proximal to the distal 1992; Ferri and Liquori, 1994; Ferri et this study to know where the stem cells and they are likely to do such in the Va- mucosa of the stomach. At the proxy- al., 1999). While, we found mucous- are located and how the lining epithe- ranus niloticus. This first report on of mal portion of the stomach, the oxynti- secreting cells in the upper part of the lium is replaced in the intestinal tract of the alimentary tract of the Egyptian Va- copeptic cells have characteristic fea- fundic glands and in the whole pyloric the Varanus niloticus. Below the epi- ranus niloticus highlighting the general tures of protein synthesizing cells; well glands elaborate both acidic and neutral thelium is the lamina propria consisting morphology, mucous contents as well developed rough endoplasmic reticulum mucosubstances as they stained posi- of blood vessels and connective tissue. as locations and appearance of the en- and many granules, similar to pepsino- tive for both PAS and AB and that simi- The muscularis mucosa is very thin and docrine cells may be the beginning of gen-secreting chief cells of mammals. lar to mucous neck cells of the mamma- consists of a single layer of smooth more interest in this species. Further J. Vet. Anat. 41 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. studies are required to explore the his- Burrell, M. A., Villaro, A. C. and Sesma, "Characterization of secretory cell Yamashita, T. (1982a). tological and physio-logical characteris- P. (1992). glycocon-jugates in the alimen- study on the glucagon cells in the tics of this animal species, to under- "Evidence for the coloca-lization tary tract of the ruin lizard (Podar- feline gastric glands." Nippon Jui- stand theory of development of reptilian of gastrin/CCK- and PYY/PP- cis sicula campestris De Betta) by gaku Zasshi 44(5): 849-51. species in comparison to known mam- immunoreactive substances in means of lectin histochemistry." Kitamura, N., Yamada, J., Yamashita, malian development, and to investigate the small intestine of the lizard Acta Histochem 93(1): 341-9. T. and Misu, M. (1982b). the possibility of using this species in Pod-arcis hispanica: immuno- Ferri, D. and Liquori, G. E. (1994). "Im- Endocrine cells in the gastro- the experiments related to the digestive cytochemical and ultra-structural munohistochemical investi- intestinal tract of the cat as re- physiology. study." Gen Comp Endocrinol gations on the pyloric glands of vealed by various staining me- 88(1): 40-9. the ruin lizard (Podarcis sicula thods." Nippon Juigaku Zasshi Acknowledgment Capula, M. (1990). The Macdonald en- campestris de Betta)." Acta His- 44(3): 427-31. cyclopedia of amphibians and tochem 96(1): 96-103. Krause, W. J., Yamadaj, J. and Cutts, The authors thank Mr. Mohamed Abdul- reptiles. The Macdonald encyclo- Ferri, D., Liquori, G. E. and Scillitani, G. H. (1985). "Quantitative distribu- lah and Mr. Elsayed Seedik, Faculty of pedia of amphibians and reptiles. (1999). tion of enteroendocrine cells in Veterinary Medicine, South Valley Uni- London and Sydney, Macdonald. "Morphological and histo- the gastrointestinal tract of the versity, for assistance in collecting the D'Este, L., Wimalawansa, S. J. and chemical variations of mucous adult opossum, Didelphis virgi- samples. Renda, T. G. (1995). and oxynticopeptic cells in the niana." J. Anat 140(4): 591-605. "Amylin-immunoreactivity is co- stomach of the seps, Chalcides Luppa, H. (1 977). Histology of the di- References stored in a serotonin cell sub- chalcides." J Anat 194 ( Pt 1): 71- gestive tract,. Biology of the Rep- population of the vertebrate sto- 7. tilia. Gans, C. and Parsons, T. Alden, P., Estes, R., D., S. and mach and duodenum." Arch His- Gilbert, S. F. (1997) New York, A cademic Press. Vol McBride, B. (2005). Collins tol Cytol 58(5): 537-47. Developmental biology. Sun- 6: 225-313. African Wildlife Harper Collins. El-Salhy, M., Grimelius, L., Wilander, derland, Mass., Sinauer Asso- Madrid, J. F., Ballesta, J., Pastor, L. M., Alumets, J., Ekelund, M., El Munshid, E., Abu-Sinna, G. and Lundqvist, ciates. Perez-Tomas, R. and Hernandez, H. A., Hakanson, R., Loren, I. and G. (1981). "Histological and im- Giraud, A. S., Yeomans, N. D. and St F. (1989). "Distribution of mucins Sundler, F. (1979). "Topography muno-histochemical studies of John, D. J. (1979). in the mucosa of the digestive of somatostatin cells in the sto- the endocrine cells of the gastro- "Ultrastructure and cyto-chemistry tract of reptiles: a histochemical mach of the rat: possible func- intestinal mucosa of the toad (Bu- of the gastric mucosa of a reptile, study." Acta Histochem 85(2): tional significance." Cell Tissue fo regularis)." Histochemistry Tiliqua scincoides." Cell Tissue 117-29. Res 202(2): 177-88. 71(1): 53-65. Res 197(2): 281-94. Ota, H., Nakayama, J., Momose, M., Alumets, J., Sundler, F. and Hakanson, Elliott, J. R. (2007). Overview of Reptile Holmberg, A., Kaim, J., Persson, A., Kurihara, M., Ishihara, K., Hotta, R. (1977). "Distribution, ontogeny Biology, Anatomy, and Histology. Jensen, J., Wang, T. and K. and Katsuyama, T. (1998). and ultrastructure of somatostatin Infectious Diseases and Patho- Holmgren, S. (2002). "Effects of "New monoclonal antibodies immunoreactive cells in the pan- logy of Reptiles. Elliott., J. R. digestive status on the reptilian against gastric gland mucous cell- creas and gut." Cell Tissue Res Brooklyn, New Y ork, Taylor & gut." Comp Biochem Physiol A type mucins: a comparative im- 185(4): 465-79. Francis Group: 1-25. Mol Integr Physiol 133(3): 499- munohistochemical study." Histo- Arena, P. C., Richardson, K. C. and Eurell, J. N. and Frappier, B. L. 518. chem Cell Biol 110(2): 113-9. Yamada, J. (1990). "An immuno- (2006).Dellmann's textbook of Junqueira, L., Carneiro, J. and Kelley, Parillo, F., Gargiulo, A. M. and histochemical study of endocrine veterinary histology. Ames, Iowa, R. (1998). Basic Histology. stam- Fagioli,O. (2004) :"Complex car- cells of the alimentary tract of the Blackwell Pub. ford, Connecticut, Appleton & bo-hydrates occurring in the di- King's skink (Egernia kingii)." J Ferri, D. and Liquori, G. E. (1992). Lange. gestive apparatus of Umbrina cir- Anat 170: 73-85. Kitamura, N., Yamada, J. and

J. Vet. Anat. 42 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. studies are required to explore the his- Burrell, M. A., Villaro, A. C. and Sesma, "Characterization of secretory cell Yamashita, T. (1982a). tological and physio-logical characteris- P. (1992). glycocon-jugates in the alimen- study on the glucagon cells in the tics of this animal species, to under- "Evidence for the coloca-lization tary tract of the ruin lizard (Podar- feline gastric glands." Nippon Jui- stand theory of development of reptilian of gastrin/CCK- and PYY/PP- cis sicula campestris De Betta) by gaku Zasshi 44(5): 849-51. species in comparison to known mam- immunoreactive substances in means of lectin histochemistry." Kitamura, N., Yamada, J., Yamashita, malian development, and to investigate the small intestine of the lizard Acta Histochem 93(1): 341-9. T. and Misu, M. (1982b). the possibility of using this species in Pod-arcis hispanica: immuno- Ferri, D. and Liquori, G. E. (1994). "Im- Endocrine cells in the gastro- the experiments related to the digestive cytochemical and ultra-structural munohistochemical investi- intestinal tract of the cat as re- physiology. study." Gen Comp Endocrinol gations on the pyloric glands of vealed by various staining me- 88(1): 40-9. the ruin lizard (Podarcis sicula thods." Nippon Juigaku Zasshi Acknowledgment Capula, M. (1990). The Macdonald en- campestris de Betta)." Acta His- 44(3): 427-31. cyclopedia of amphibians and tochem 96(1): 96-103. Krause, W. J., Yamadaj, J. and Cutts, The authors thank Mr. Mohamed Abdul- reptiles. The Macdonald encyclo- Ferri, D., Liquori, G. E. and Scillitani, G. H. (1985). "Quantitative distribu- lah and Mr. Elsayed Seedik, Faculty of pedia of amphibians and reptiles. (1999). tion of enteroendocrine cells in Veterinary Medicine, South Valley Uni- London and Sydney, Macdonald. "Morphological and histo- the gastrointestinal tract of the versity, for assistance in collecting the D'Este, L., Wimalawansa, S. J. and chemical variations of mucous adult opossum, Didelphis virgi- samples. Renda, T. G. (1995). and oxynticopeptic cells in the niana." J. Anat 140(4): 591-605. "Amylin-immunoreactivity is co- stomach of the seps, Chalcides Luppa, H. (1 977). Histology of the di- References stored in a serotonin cell sub- chalcides." J Anat 194 ( Pt 1): 71- gestive tract,. Biology of the Rep- population of the vertebrate sto- 7. tilia. Gans, C. and Parsons, T. Alden, P., Estes, R., D., S. and mach and duodenum." Arch His- Gilbert, S. F. (1997) New York, A cademic Press. Vol McBride, B. (2005). Collins tol Cytol 58(5): 537-47. Developmental biology. Sun- 6: 225-313. African Wildlife Harper Collins. El-Salhy, M., Grimelius, L., Wilander, derland, Mass., Sinauer Asso- Madrid, J. F., Ballesta, J., Pastor, L. M., Alumets, J., Ekelund, M., El Munshid, E., Abu-Sinna, G. and Lundqvist, ciates. Perez-Tomas, R. and Hernandez, H. A., Hakanson, R., Loren, I. and G. (1981). "Histological and im- Giraud, A. S., Yeomans, N. D. and St F. (1989). "Distribution of mucins Sundler, F. (1979). "Topography muno-histochemical studies of John, D. J. (1979). in the mucosa of the digestive of somatostatin cells in the sto- the endocrine cells of the gastro- "Ultrastructure and cyto-chemistry tract of reptiles: a histochemical mach of the rat: possible func- intestinal mucosa of the toad (Bu- of the gastric mucosa of a reptile, study." Acta Histochem 85(2): tional significance." Cell Tissue fo regularis)." Histochemistry Tiliqua scincoides." Cell Tissue 117-29. Res 202(2): 177-88. 71(1): 53-65. Res 197(2): 281-94. Ota, H., Nakayama, J., Momose, M., Alumets, J., Sundler, F. and Hakanson, Elliott, J. R. (2007). Overview of Reptile Holmberg, A., Kaim, J., Persson, A., Kurihara, M., Ishihara, K., Hotta, R. (1977). "Distribution, ontogeny Biology, Anatomy, and Histology. Jensen, J., Wang, T. and K. and Katsuyama, T. (1998). and ultrastructure of somatostatin Infectious Diseases and Patho- Holmgren, S. (2002). "Effects of "New monoclonal antibodies immunoreactive cells in the pan- logy of Reptiles. Elliott., J. R. digestive status on the reptilian against gastric gland mucous cell- creas and gut." Cell Tissue Res Brooklyn, New Y ork, Taylor & gut." Comp Biochem Physiol A type mucins: a comparative im- 185(4): 465-79. Francis Group: 1-25. Mol Integr Physiol 133(3): 499- munohistochemical study." Histo- Arena, P. C., Richardson, K. C. and Eurell, J. N. and Frappier, B. L. 518. chem Cell Biol 110(2): 113-9. Yamada, J. (1990). "An immuno- (2006).Dellmann's textbook of Junqueira, L., Carneiro, J. and Kelley, Parillo, F., Gargiulo, A. M. and histochemical study of endocrine veterinary histology. Ames, Iowa, R. (1998). Basic Histology. stam- Fagioli,O. (2004) :"Complex car- cells of the alimentary tract of the Blackwell Pub. ford, Connecticut, Appleton & bo-hydrates occurring in the di- King's skink (Egernia kingii)." J Ferri, D. and Liquori, G. E. (1992). Lange. gestive apparatus of Umbrina cir- Anat 170: 73-85. Kitamura, N., Yamada, J. and

J. Vet. Anat. 43 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al.

rosa (L.) fry." Vet Res Commun Holroydc, A. P. ( 2008 ). "Earliest 28(4): 267-78. African Record of the Varanus Parsons, T. and Cameron, J. ( 1977). Stem-Clade (Squamata: Vara- Internal relief of the digestive nidae) from the Early Oligocene tract. Biology of the Reptilia. Par- of Egypt." Journal of Verteb-rate sons, T. and Gans, C. New York, Paleontology 28(3): 909-913. Academic Press Vol 6: 159–223. Suganuma, T., Katsuyama, T., Putterill, J. F. and Soley, J. T. (2003). Tsukahara,M.,Tatematsu,M., Sa- "General morpho-logy of the oral kakura, Y. and Murata, F. (1981). cavity of the Nile crocodile, Cro- "Comparative histochemi-cal codylus niloticus (Laurenti, study of alimentary tracts with 1768). I. Palate and gingivae." special reference to the mucous Onderstepoort J Vet Res 70(4): neck cells of the stomach." Am J 281-97. Anat 161(2): 219-38. Putterill, J. F. and Soley, J. T. (2004). Uriona, T. J., Farmer, C. G., Dazely, J., "General morpho-logy of the oral Clayton, F. and Moore, J. (2005). cavity of the Nile crocodile, Cro- "Structure and function of the codylus niloticus (Laurenti, eso-phagus of the American alli- 1768). II. The tongue." Onderste- gator (Alligator missis- poort. J Vet Res 71(4): 263-77. sippiensis)." J Exp Biol 208 (Pt Putterill, J. F. and Soley, J. T. (2006). 16): 3047-53. "Morphology of the gular valve of the Nile crocodile, Crocodylus nilo-ticus (Laurenti, 1768)." J Morphol 267(8): 924-39. Sato, A. and Spicer, S. S. (1980)."Ultrastructural cytoche- mistry of complex carbohydrates of gastric epithelium in the guinea pig." Am J Anat 159(3): 307-29. Secor, S. M. and Diamond, J. (1998). "A vertebrate model of extreme physiological regulation." Nature 395 (6703): 659-62.

Selvan, P. S., Ushakumary, S. and

Ramesh, G. (2008). "Studies on Figure (1): General morphology of the alimentary tract of the Varanus niloticus the Histochemistry of the Proven- Paraffin sections from the esophageus (A), fundic (B) and pyloric stomach(C) , and triculus and Gizzard of Post- small intestine (D) stained with haematoxylin and eosin showing the general outline of Hatch Guinea Fowl (Numida me- the alimentary tract of the Varanus Niloticus . Surface lining epithelium (ep), gastric leagris)." Inter-national Journal of pits (gp), lamina propria (lp), fundic glands (fg), pyloric glands (pg) muscularis mucosa Poultry Science 7 (11). (mm), submucosa (sm), inner circular (ic) and outer longitudinal (ol) tunica muscularis Smith, T., Bhullar, S. B.-A. and (tm) and serosa (sr). Bars = 160 µm in parts A, C and D, and 40 µm in part B.

J. Vet. Anat. 44 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. rosa (L.) fry." Vet Res Commun Holroydc, A. P. ( 2008 ). "Earliest 28(4): 267-78. African Record of the Varanus Parsons, T. and Cameron, J. ( 1977). Stem-Clade (Squamata: Vara- Internal relief of the digestive nidae) from the Early Oligocene tract. Biology of the Reptilia. Par- of Egypt." Journal of Verteb-rate sons, T. and Gans, C. New York, Paleontology 28(3): 909-913. Academic Press Vol 6: 159–223. Suganuma, T., Katsuyama, T., Putterill, J. F. and Soley, J. T. (2003). Tsukahara,M.,Tatematsu,M., Sa- "General morpho-logy of the oral kakura, Y. and Murata, F. (1981). cavity of the Nile crocodile, Cro- "Comparative histochemi-cal codylus niloticus (Laurenti, study of alimentary tracts with 1768). I. Palate and gingivae." special reference to the mucous Onderstepoort J Vet Res 70(4): neck cells of the stomach." Am J 281-97. Anat 161(2): 219-38. Putterill, J. F. and Soley, J. T. (2004). Uriona, T. J., Farmer, C. G., Dazely, J., "General morpho-logy of the oral Clayton, F. and Moore, J. (2005). cavity of the Nile crocodile, Cro- "Structure and function of the codylus niloticus (Laurenti, eso-phagus of the American alli- 1768). II. The tongue." Onderste- gator (Alligator missis- poort. J Vet Res 71(4): 263-77. sippiensis)." J Exp Biol 208 (Pt Putterill, J. F. and Soley, J. T. (2006). 16): 3047-53. "Morphology of the gular valve of the Nile crocodile, Crocodylus nilo-ticus (Laurenti, 1768)." J Morphol 267(8): 924-39. Sato, A. and Spicer, S. S. (1980)."Ultrastructural cytoche- mistry of complex carbohydrates of gastric epithelium in the guinea pig." Am J Anat 159(3): 307-29. Secor, S. M. and Diamond, J. (1998). "A vertebrate model of extreme physiological regulation." Nature 395 (6703): 659-62.

Selvan, P. S., Ushakumary, S. and

J. Vet. Anat. 45 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al.

Figure (2): Higher magnification showing details of some structures in the ali- Figure (3): Mucous contents of the alimentary tract of the Varanus niloticus mentary tract of the Varanus niloticus. Paraffin sections from the esophageus (A, B), and fundic (C) and pyloric stomach stained with haematoxylin and eosin showing Paraffin sections from the surface lining epithelium of the esophageus (A), stomach (C) some details of the alimentary tract of the Varanus Niloticus . Surface lining epithelium and pyloric mucous glands stained with PAS and AB. Arrowheads indicate PAS posi- (ep), mucous secreting goblet cells (gc), gastric pits (gp), lamina propria (lp), fundic tive, and Arrows indicate AB positive reactions. Bars = 10 glands (fg), mucous cells in fundic glands (mc), pyloric glands (pg), muscularis mucosa (mm), submucosa (sm) and tunica muscularis (tm). Bars = 90 µm in A, 10 µm in B, and 20 µm in C and D. J. Vet. Anat. 46 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al.

Figure (2): Higher magnification showing details of some structures in the ali- Figure (3): Mucous contents of the alimentary tract of the Varanus niloticus mentary tract of the Varanus niloticus. Paraffin sections from the esophageus (A, B), and fundic (C) and pyloric stomach stained with haematoxylin and eosin showing Paraffin sections from the surface lining epithelium of the esophageus (A), stomach (C) some details of the alimentary tract of the Varanus Niloticus . Surface lining epithelium and pyloric mucous glands stained with PAS and AB. Arrowheads indicate PAS posi- (ep), mucous secreting goblet cells (gc), gastric pits (gp), lamina propria (lp), fundic tive, and Arrows indicate AB positive reactions. Bars = 10 glands (fg), mucous cells in fundic glands (mc), pyloric glands (pg), muscularis mucosa (mm), submucosa (sm) and tunica muscularis (tm). Bars = 90 µm in A, 10 µm in B, and 20 µm in C and D. J. Vet. Anat. 47 Vol 2 No1, (2009) 35 - 48 Varanus niloticus Ahmed et al. Morphology and Lectin histochemistry of the testes of brown-banded bamboo shark (Chiloscyllium punctatum)

Kassab M 1; Yanai T 2; Ito K 2; Sakai H 2; Mesegi T 2; Yanagisawa M 3

1-Department of Cytology and Histology, Fac.Vet. Med., Kafr El- sheikh Univ., Egypt 2-Department of Pathology, Fac. of Biological Science, Gifu Univ., Japan 3-Okinawa Churaumi Aquarium, Japan Email: [email protected] ______With 22 figures Received at August 2009, accepted for publication October 2009

Abstract germinal zone was not labeled to any sugar, while the spermatogonial zone The testes of three brown-banded was labeled to galactosamine. The bamboo male sharks collected from spermatocyte zone was labeled to Okinawa Churaumi Aquarium, Japan glucose, galactose and glucosamine were used in this study. The testes within the Leydig cells, while the were studied grossly and micro- spermatocysts were labeled only to scopically. In addition, conventional and the galactose and glucose-amine. The lectin histochemistry (panel of 8 HRP spermatocyst of the spermatide zone lectins, UEA-I, DBA, LCA, PNA, ConA, was similar to that of the spermatocyte PHA-E4, WGA and RCA 120) were zone while the Leydig cells were applied for studying the glycoco- labeled to all sugars under investi- njugates. gation. The spermatozoal zone was labeled to all sugars under investigation The testes are suspended to the dorsal either to the spermatocyst or to the wall by mesorchium. They are covered Leydig cells. At the degenerative zone, ventromedially by the epigonal organ Leydig cells were labeled to all sugars (Hematopoietic organ). The testis is under investigation while the spermato- divided into germinal, spermatogonial, Figure (4): Enteroendocrine cells localization in the alimentary tract of the Varanus cyst was labeled to glucose and gluco- sperma-tocytes, spermatid, spermato- niloticus samine only. zoal and degenerative zones. Paraffin sections from the lining epithelium of the esophageus (A) and the pyloric region In conclusion, our results indicate that Analysis of the sugar binding-lectins in of the stomach (B) stained according to Grimelius impregnation technique. Arrows indi- the structure of the testes of the brown- the shark testes revealed the presence cate enteroendocrine cells among the surface lining epithelium of the esophageus (A) banded bamboo shark simulate that of of all sugars under investigation, and mucous cells of the pyloric glands (B). Bars in parts A and B = 10 the cartilaginous fish. There is pro- although they varied in distribution gressive increase in glycolsylation throughout the different zones. The during spermatogenesis, especially at

J. Vet. Anat. 48 Vol 2 No1, (2009) 35 - 48