The Normal Structure of Regional Feline Gastric Mucosae: Scanning Electron Microscopic Study

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Volume 1 Number 4 Article 34

7-30-1987

M. Al-Tikriti The University of Tennessee

F. Al-Bagdadi Louisiana State University

R. W. Henry The University of Tennessee

J. Hoskins Louisiana State University

C. Titkemeyer Louisiana State University

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Recommended Citation Al-Tikriti, M.; Al-Bagdadi, F.; Henry, R. W.; Hoskins, J.; Titkemeyer, C.; and Strain, G. (1987) "The Normal Structure of Regional Feline Gastric Mucosae: Scanning Electron Microscopic Study," Scanning Microscopy: Vol. 1 : No. 4 , Article 34. Available at: https://digitalcommons.usu.edu/microscopy/vol1/iss4/34

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Authors M. Al-Tikriti, F. Al-Bagdadi, R. W. Henry, J. Hoskins, C. Titkemeyer, and G. Strain

This article is available in Scanning Microscopy: https://digitalcommons.usu.edu/microscopy/vol1/iss4/34 Scanning Microscopy, Vol. 1, No. 4, 1987 (Pages 1871-1880) 0891-7035/87$3.00+.00 Scanning Microscopy International, Chicago (AMF O'Hare), IL 60666 USA

THE NORMALSTRUCTURE OF REGIONALFELINE GASTRIC MUCOSAE: SCANNINGELECTRON MICROSCOPIC STUDY

M. Al-Tikritia*, F. Al-Bagdadib, R. W. Henrya, J. Hoskinsc, C. Titkemeyerb, G. Straind

aDepartment of Animal Science, co lege of Veterinary Medicine, The University of Tennessee, Knoxville, TN 37901-1071. 6Department of Veterinary Anatomy and Fine Structure, cDepartment of Veterinary Clinical Sciences, dDepartment of Veterinary Physiology, Pharmacology and Toxicology, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, 70803.

(Received for publication April 9, 1987, and in revised form July 30, 1987)

Abstract Introduction Regions of cat's stomach can be identified by The gastric mucosa forms the interface looking at the surface epithelial cells by between the internal and external environments. scanning electron microscopy (SEM). The luminal It is involved in many physiological processes, surface of cells of the cardiac region were and its morphology varies with function (Ito, elongated, of the fundus rounded, of the corpus 1974; Miller and Revel, 1975; Wood and Dubois, polygonal shaped, and of the pyloric region 1983). Surface topography of the stomach is used diamond shaped. The quantity and di stri but ion of for diagnostic information when evaluating microvi 11i covering the epithelial ce 11s varies, biopsies for pathophysiologic studies (Burhol, being abundant and evenly distributed in the 1968; Takagi et al., 1974). Due to high cardiac region and gradually decreasing in number resolution, great depth of field, rapidity of toward the gastro-duodenal junction, where they tissue preparation, and three dimensional viewing were confined to cell perimeters. The colliculi of tissue surface, scanning electron microscopy varied in shape and distribution from few in the affords a unique tool for surface morphological fundus and corpus to numerous in the pyloric studies especially in the gastrointestinal tract region. Large numbers of gastric pits were (Pfeiffer, 1971). Many studies of the gastric present in the corpus. They diminish toward both mucosa (both normal and diseased) have been the cardia and gastro-duodenal junction. The reported in man and animals ( Ogata and Murata, cardiac and pyloric glands were coiled. The 1969; Pfeiffer, 1970a,b; Capoferro, 1974; Takagi gastric glands (glandula gastrica propria) were et al., 1974). Similar studies of the stomach of straight tubules in the fundus and coiled in the cats are less numerous (Al-Tikriti et al., 1984, corpus. All luminal surfaces of glandular 1987), even though the cat has been used as an epithelial cells were covered with microvilli, experimental animal (Biancani et al., 1982; Clerc but the regional distribution of microvilli on and Mei, 1983; Clerc, 1983; Al-Tikriti, 1984). the cell was variable. Parietal, mucous neck, The objective of this study is to describe the and chief (zymogen) cells were identified by normal surface mrphology of various regions of their cytoplasmic structure. Parietal cells had the gastric mucosa as well as the surface long apical microvilli, mucous neck cells morphology of the various glandular epithelia in contained large numbers of globular mucous the cat's stomach. granules, and chief cells were vacuolated. A few G cells (Endocrinocytus gastrointestinalis) were Materials and Methods seen in the cardiac region, large numbers in the pyloric region, and not found in fundus or Animals corpus. Twelve healthy adult cats of mixed breeds and sexes were used in this study. The cats were conditioned in the Louisiana State University vivarium for two weeks. The cats were fed regularly, but were fasted 24 h before ~ Words: Cardiac, Gastric, and Pyloric glands; euthanasia. Digestive system; Feline; Gastric mucosa; Necropsy and Collection of Samples Scanning electron microscopy. The cats were euthanatized by intravenous injection of T-61 Euthanasia Solution (American Hoechst Corporation). The abdominal and thoracic *Address For Correspondence: M. Al-Tikriti, cavities were immediately opened and the stomach removed, washed, and fixed utilizing the Department of Animal Science, College of procedure described by Al-Tikriti et al., (1986). Veterinary Medicine, The University of After washing the stomach gently with saline and Tennessee, Knoxville, TN 37901-1071. Phone gloved hand, the stomach was moderately stretched No.: (615) 546-9230 Ext. 328. with mucosal surface up, and the edges were

1871 Al-Tikriti et al. pinned to a paraffin tray. Subsequently, the pit ostia were surrounded by circumferentially stomach was thoroughly washed with saline oriented epithelial cells. solution and submerged in a solution of 5% At higher magnification, the epithelial cells gl utara l dehyde in phosphate buffer ( pH 7 .4, were rounded with a dome-like surface. The 0.15M). Th~ stomach was left overnight in surface was covered by short microvilli (Fig. 8). fixative at 4 C. The next day, the stomach was The microvil l i were more numerous near the ce 11 washed with phosphate buffer (pH 7.4, 0.2M). perimeter. A side view of the fundic region Samples were cut from the gastro-esophagea l revealed the gastric glands (Glandula gastrica junction, cardiac region, fundus, corpus, pyloric propria) arranged in tall straight columns from region, and gastro-duodenal junction. the Lamina muscularis mucosae to the surface Scanning Electron Microscopic Procedure epithelium (Fig. 9). Individual glandular cells After initial fixation, the samples were were recognized as polygonal in shape with knob- washed three times with phosphate buffer (pH 7.4, 1i ke projections within the column of cells. 0.2M). Subsequently, the samples were postfixed Ce11 s concentrated in the isthmus of the fundi c for 90 minutes in 1% osmium tetroxide in glands appeared to be parietal cells phosphate buffer ( pH 7 .4, 0 .15M), washed three (Exocrinocytus parietalis). times (10 minutes each) with phosphate buffer, Corpus ventriculi and dehydrated in a graded series of acetone The surface epithelium of this region also solutions (70%, 80%, 95%, with three changes in had high ridges of short length, separating the 100% acetone). Eventually, the samples were numerous ostia of the gastric pits (Fig. 10). dried in a critical point drying apparatus with The ostia of the pits were of different sizes and liquid co,. The samples were mounted on aluminum shapes. A few mononuclear leukocytes were seen stubs, sputter coated with a 15nm layer of gold squeezed between the epithelial cells. palladium, and examined with a Cambridge The epithelial cells were polygons with short Stereoscan 150 Mark 2 SEM, operating at 20kV. microvi 11 i con cent rated at the perimeter of the cell. Some cells showed colliculi of different Results sizes (Fig. 11). A side view of the corpus region showed cross-sectional profiles of the Gastro-esophageal junction long, coiled gastric glands (Fig. 12). The At the gastro-esophageal junction, the mucous neck ce 11s (Mucocytus cervical is) in the epithelium abruptly changes from stratified gastric glands were characterized by irregular squamous ( Epithelium strati fi ca tum squamosum) to globules which corresponded to mucous granules simple columnar epithelium (Epithelium simplex (Fig. 13). Their luminal surfaces had columnare) (Fig. 1). At low magnification, the l ongi tudi na l ridges surrounded by microvil l i. gastric pit (Foveola gastrica) openings, through The chief cells (Exocrinocytus principalis) were which the cardiac glands (Glandula cardiaca) concent rated predominantly in the basal portion open, were observed (Fig. 2). The openings were (Pars principalis) of the gastric glands. Their of different shapes and sizes, and some of them cytoplasmic matrix contained empty vacuoles of showed flakes of precipitated mucus oozing from various sizes (Fig. 14). Their luminal surfaces their ostia. The surface of the cardiac region were covered by short microvi 11i. The parietal (Pars cardiaca) was marked by low ridges that cells had relatively long microvilli projecting separate the ostia of the gastric pits. In into the lumen of the gastric glands (Fig. 15). addition to debris of exfoliated cells, mononuclear leukocytes passing between the Fig. 1. Gastro-esophageal junction. E surface epithelial cells were observed (Fig. 2). esophagus C - cardiac region. Bar= 200 µm. At higher magnification the elongated epithelial cells were delineated. Their surfaces Fig. 2. Low magnification of cardiac gland were covered with minute microvilli of irregular region with ostia of gastric pits (P) and shapes and length (Fig. 3). A side view of the mononuclear cells (Mc). Bar= 50 µm. gastro-esophageal junction showed that the cardiac glands were coiled and sectioned profiles Fig. 3. High magnification of cardiac surface of different shapes were observed (Fig. 4). epithelial cells which are covered by minute Higher magnification revealed the glands were microvilli. Bar= 8 µm. lined by polygonal glandular epithelial cells (Exocrinocytus cardiacus). The luminal surfaces Fig. 4. Side view of wall of the gastro of these ce 11s had microvi 11i which were more esophageal junction. Cardiac glands are simple numerous at their perimeter (Fig. 5). Amongthe coiled. E = esophagus, C - cardiac region. Bar glandular epithelial cells were a few cells = 200 µm. characterized by long microvi 11 i projecting from their luminal surface (Fig. 6). Fig. 5. Low magnification of cardiac glands. Fundus ventriculi Luminal surface of glandular cells are covered ---The surface of the fundus had ridges with microvilli (Mv). (*) - indicates area of separating the ostia of the gastric pits. A few figure 6. Bar= 10 µm. mononuclear leukocytes were observed between the epithelial cells (Fig. 7). Many gastric pits had Fig. 6. High magnification of the labeled area flakes of precipitated gastric juice occluding (*) in figure 5. G cell has long microvilli (Mv) their ostia. The gastric pits of the fundus were projecting into the lumen of the cardiac gland. more numerous than in the cardiac region. The Bar = 4 µm.

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Pars pylorica The mucous neck ce 11s were characterized by the A1 though there was no true 1i ne of presence of globule-like granules in their demarcation, two morphologically different cytoplasm similar to those described by portions were observed. 1. The pyloric antrum Mackercher et al. (1978) in the human. (Antrum pyloricum) was characterized by its One of the problems of studying the surface surface thrown up in a labyrinthine fashion which morphology of the stomach in various animals is obscured the ostia of the gastric pits (Fig. 16). the presence of opaque materials coating the 2. The pyloric canal's (Canalis pyloricus) gastric mucosa. This coating material obscures surface was marked by 1ong anastomos i ng ridges structure detail of the gastric epithelial cells. which separated the ostia of the gastric pits Different methods of removing this coat have been (Fig. 17). These ridges gradually become taller tried unsuccessfully (Takagi et al., 1974; as they are changing to the fi nger-1 i ke Zalewsky and Moody, 1979; Wood and Dubois, 1981). projections found in the duodenum (Fig. 18). At In this study we successfully used the method higher magnification, the individual epithelial recently described by Al-Tikriti et al. (1986) to ce 11 s were c 1 early de 1 i neated and diamond shaped remove this coating material. Even so, a few (Fig. 19). Their free surface was relatively ostia of gastric pits were occluded by convex. The majority of the cel 1 surfaces were precipitated flakes of mucus and cell debris. covered with numerous co 11 i cul i. However, a few The number, shape, and size of gastric pit ostia short mi crovi 11 i were present at the ce 11 's varies regionally. The ostia were small and few perimeter and intercellular space. A side view in number in the cardiac region. They reached of the pyloric region showed that the pyloric their greatest number in the corpus and gradually glands (Glandula pylori ca) were coiled and decreased in number toward the pylorus. Variation scattered in solitary groups in the lamina in number of ostia is attributed to the increased propria mucosae (Fig. 20). number of gastric glands in the corpus region. The pyloric glands were lined by cuboidal to In addition, the large openings of the gastric low columnar glandular epithelial cells {Figs. 21 pits in the corpus suggest that these glands and 22). Their luminal surfaces were covered produce 1arger amounts of secretory product than with evenly distributed, abundant, short the cardiac and pyloric glands. Hence, larger microvilli, especially near the neck of the gland glandular openings are required to discharge (Fig. 21). In the basal portion of the gland, their secretory products. their surf aces were covered by microvi 11i and the At higher magnification, the surface perimeter of the cells appeared as ridges. These epithelial cells of the cat appear as gently ridges were extensively covered by short sloping domes. The gastric epithelial cells vary microvilli (Fig. 22). Cells with long microvilli in size and shape. They are elongated in the were seen in large numbers, especially at the cardiac region, rounded in the fundus, polygonal base of the pyloric glands (Fig. 23). in the corpus, and diamond shaped in the pyloric region. The surface epithelial cells are covered Discussion with microvi 11 i similar to that reported in man and ferret (Pfeiffer, 1970a,b). The microvilli The present investigation provides a cover the epithelial cells of all regions of the description of the mucosae of the cat's stomach stomach. However, they differ in their and associated glands. New techniques have been concentration and distribution due to different deve 1oped to a 11ow examination of subepithe 1i a 1 physiological activities (Wood and Dubois, 1983). structures and cel 1 ular components with the Microvilli covered the entire surface of the scanning electron microscope. These include fracturing the tissue or by preparing it with Fig. 7. Low magnification of fundus showing blunt dissection (Hattori and Fujita, 1974; ostia of gastric pits surrounded by Boyde, 1975; Miller and Revel, 1975; Mackercher circumferentially oriented epithelial cells. et al., 1978). In this study, blunt dissection Mononuclear cell (Mc). Bar = 100 µm. was used successfully to view the gastric glands and other structures in the Lamina propri a Fig. 8. High magnification of fundus. mucosae. The gastric pits are tubular and Epithelial cells have convex surfaces covered descend from the epithelial surface to the with microvilli. Bar= 8 µm. isthmus of the gland at which point the parietal cells open. The gastric glands appear as Fig. 9. Side view of fundus. Gastric glands are straight columns in the fundus but coiled in the in columns. Mm - muscularis mucosae, Pc - corpus. parietal cells. Bar= 200 µm. Three types of cells were identified in the gastric glands. The parietal cells, when viewed Fig. 10. Low magnification of corpus showing from the side, had knob-like projections and long widely opened gastric pits. Bar= 100 µm. microvilli projecting into the lumen of the gland. This description was similar to that Fig. 11. High magnification of surface reported in the go 1den hamster ( Hattori , 1974). epithelial cells of corpus showing few The zymogen (chief) cells were recognized by the mi crovi 11 i. Co - colliculi. Bar= 8 µm. presence of empty vacuoles in their cytop las mic matrix. These empty vacuoles were originally Fig. 12. Side view of corpus region. Gastric filled with zymogen granules (Granulum zymogeni) glands are coiled. Mm- muscularis mucosae. Bar that were dissolved during tissue preparation. = 200 µm.

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1875 Al-Tikriti et al. cells of the cardiac and fundic regions, but they of America. Detroit, 1984, pp. 242-243, (San decrease in number and concentrate near the Francisco Press, San Francisco, 1984). perimeter of the epithelial cells in the corpus Al-Tikriti M (1984). Light and scanning and pyloric region. Similar distribution of electron microscopy of feline gastric mucosa microvilli has been described in man (Mackercher, under normal conditions and following et a 1. , 1978) and in the ferret ( Pfeiffer subdiaphragmatic transection of the vagus nerve. 1970a,b). In addition,another surface pp 65-122, (Thesis, Louisiana State University, modification is the presence of colliculi of Baton Rouge, LA., 1984). varying sizes. These colliculi are found in Al-Tikriti M, Henry RW, Al-Bagdadi FK, increased quantity in the corpus and pyloric Hoskins J, Titkemeyer C (1986). Scanning region. Coll iculi are thought to be formed by electron microscopic study of the surface of mucous secreting granules which gather beneath feline gastric epithelium: A simple method of the cell membrane (Takagi et al., 1974). removing the coating material. Scanning Electron It is of interest that various workers have Microsc. 1986; 111:949-952. demonstrated increased numbers of degenerated Al-Tikriti M, Al-Bagdadi FK, Henry RW, gastric epithelial cells (Pfeiffer, 1970a). In Hoskins J, Titkemeyer C (1987). Correlative this study, cellular debris and small holes in 1 i ght and scanning e 1ect ron microscopic study of the surface epithe 1 i a 1 ce 11 s were observed in the the feline gastric mucosa: The cardiac region cardiac and pyloric regions. This suggests that (Pars cardiaca), Acta Anat 128:281-295. the stomach undergoes continua 1 degeneration and Biancani CG, Zabinski M, Kerstein M, Behar J regeneration at a slow rate similar to that (1982). Lower esophageal sphincter mechanics: described by Pfeiffer ( 1970a ,b) in man and Anatomic and physiologic relationship of the ferrets and Townsend (1961) in the rat. esophagogastric junction of cat. Often mononuclear leukocytes were observed on Gastroenterology 82:468-475. the surface epithelium. They were seen in large Boyde A (1975T, A method for the preparation numbers in the cardiac and pyloric region. These of cell surfaces hidden within bulk tissue for were the interepithelial lymphocytes described by examination in the SEM. Scanning Electron Douglas and Weetman (1975). It has been Microsc. 1975; 1975:295-304. suggested that they have an immunological Burho 1 PG ( 1968). Surface microscopic and function, transporting antibodies into the lumen histologic appearances of the gastric mucosa. to be re 1eased when they degenerate ( Burrows and Scand. J. Gastroenterology. 3:317-320. Havens, 1948; Fichtelius, 1967). Burrows W, Havens I T1948). Studies on A few endocrine cells (Endocrinocytus immunity to Asiatic cholera. V: The absorption gastrointestinalis) were observed in the cat of immune globulin from the bowel and its cardiac and pyloric regions. They are excretion in the urine and feces of experimental characterized by 1ong mi crovi 11 i projecting from animals and human volunteers. J. Infect. Dis. their luminal surface into the gland lumen. They 82:231-250. likely play a role in the mechanism of cellular - Capoferro R (1974). A scanning electron stimulation by either chemical or mechanical microscopic study of norma 1 and x-i rradi ated stimuli (Solcia et al., 1967, 1975). These guinea-pig gastric mucosa. Scand. J. endocrine cells are considered to be G cells. Gastroenterology. 9:533-538. Their i dent i fi cation is based on the observation Clerc N (1983f. Histological characteristics that the G cell contacts both the basal lamina of the lower esophageal sphincter in the cat. and the lumen of the gland (Solcia et al., 1975, Acta. Anat. fil:201-208. Al-Tikriti et al., 1987}. G cells have been identified structurally in the pyloric region of the cat and man (Vassallo et al., 1969, 1971, Fig. 13. Side view of corpus region. Luminal Forssmann and Orci, 1969) and in the cardiac surface of gastric gland is covered with mucosa of the rat (Forssmann and Orci, 1969). microvilli. Mn - mucous neck cells. Bar= 8 µm. However, their presence and function in the cardiac region of the cat remains enigmatic. Fig. 14. Side view of corpus region. Chief cells surround lumen (L) of gastric gland. Cv - Acknowledgments cytoplasmic vacuoles. Bar= 20 µm.

The authors wish to thank The University of Fig. 15. Side view of corpus. Parietal cells Tennessee, Department of Animal Science for using (Pr) have long microvilli. L - lumen of gastric their technical facilities. This work was gland. Bar= 8 µm. supported by the School of Veterinary Medicine, Organized Research Funds, and the Department of Fig. 16. Low magnification of pyloric antrum. Veterinary Anatomy and Fine Structure at Gastric pits are obscured by irregular ridges of Louisiana State University. surface epithelium. Bar= 100 µm.

References Fig. 17. Low magnification of pyloric canal. Ostia of gastric pits are separated by long Al-Tikriti M, Al-Bagdadi FK, Hoskins J, anastomosing ridges. Bar= 400 µm. Titkemeyer C, Strain G (1984). Scanning electron microscopy of feline gastric mucosa. Proc. 42nd Fig. 18. Gastro-duodenal junction. P - pylorus, Annual Meeting of the Electron Microscopy Society D - Duodenum. Bar= 400 µm. SEMof Feline Gastric Mucosa

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Clerc N, Mei N (1983). Vagal Zellforsch. Mikrosk. Anat. 118:49-67. mechanoreceptors located in the lower esophageal Wood LR, Dubois A (198""i°). Scanning electron sphincter of the cat. J. Physiol. (Lond.) microscopic studies of gastric cell surface 336 :487-498. epithelium: An evaluation of various methods of - Douglas AP, Weetman AP (1975). Lymphocytes preparation. Virchows Arch [Cell Pathol] B. and the gut. Digestion. 13:344-371. 35:207-212. Fichtelius KE (1967). The mammalian - Wood LR, Dubois A (1983). Scanning electron equivalent to bursa fabri ci i of birds. Expl. microscopy of the stomach during modifications of Cell Res. 46:231-234. acid secretion. Am. J. Physiol. 244:G475-G479. Forssmann WG, Orci L ( 1969). Zalewsky CA, Moody FG (1979)-. -Mechanisms of Ultrastructure and secretory cycle of the mucus release in exposed canine gastric mucosa. gastri n-producing eel l. Z. Zellforsch. Mikrosk. Gastroenterology. "]L:719-729. Anat. 101:419-432. Hattori T (1974). On cell proliferation Discussion with Reviewers and differentiation on the fundic mucosa of the golden hamster. Fr ctographic study combined T. Makita: Zymogen granules in chief cells have with microscopy and H1 thymidine autoradiography. been preserved in preparation for transmission Cell Tiss. Res. 148:213-226. electron microscopy. Why were they dissolved in Hattori T;--f"ujita S (1974). Fractographic this SEMstudy? study on the growth and multiplication of the Authors: The zymogen granule is a membrane bound gastric gland of the hamster: The gland division secretory vesicle. The membrane was well cycle. Cell Tiss. Res. 153:145-149. preserved. However, the content is lost during Ito S (1974). Abrief su1TTI1aryof the processing most likely due to the fact that these symposium "Cell surface topology and properties specimens are not prepared by freeze fracture. of the cell membrane". Anat. Rec. 180:165-167. When the membrane is cut during sampling the Mackercher PA, Ivey KJ, Baskin WN, Krause fluid content is lost. We are looking only on WJ (1978). A scanning electron microscopic study the surface, therefore only cut granules are of normal human oxyntic mucosa using blunt shown. The granules located deep in the tissue dissection and freeze fracture. Dig. Diseases most likely are well preserved. In TEM the 23:449-459. embedding media will impregnate and hold the - Miller MM, Revel JP (1975). Scanning content of the granule in situ. electron microscopy of epi the l i a prepared by blunt dissection. Anat. Rec. 183:339-358. T. Makita: Are you also of opinion that Ogata T, Murata F 7T969). Scanning mononuclear cells are interepithelial lymphocytes electron microscopic study on the rat gastric transporting antibodies into the lumen? You mucosa. Tohoku J. Exp. Med. 99:65-71. mentioned that they were numerous in the cardiac Pfeiffer CJ (1970a). Surface topology of and pyloric regions. Did you mean that the stomach in man and laboratory ferret. J. i mmunoacti vi ty of these two regions were higher Ultrastruct. Res. 33:252-262. than other regions? Pfeiffer CJ- (1970b). Gastric Surface Authors: It has been shown that mononuclear cells morphology in man, monkey and ferret. Evidence are interepithelial lymphocytes. However, their for in situ surface cell degeneration. Exp. Mol. role in transporting antibodies into the lumen is Pathol. 13:319-328. questionable. It is possible that the Pfeiffer CJ (1971). Scanning electron immunoactivity of these regions is higher than microscopy: A new tool for physiologic and other regions based on the evidence of the pathologic study of the digestive tract. numerous lymphocytes in these regions. Biologie et Gastro-Enterologie 4:273-277. ------Solcia E, Vassallo G, Sampietro R (1967). Fig. 19. High magnification of surface Endocrine cells in the antro-pyloric mucosa of epithelial cells of pylorus. Individual cells the stomach. Z. Zellforsch. Mikrosk. Anat. are delineated and majority of their surface is 81:474-486. covered with colliculi (Co). Bar= 20 µm. - Solcia E, Capella C, Vassallo G, Buffa R (1975). Endocrine cells of the gastric mucosa. Fig. 20. Side view of the pyloric region. The Int. Rev. Cytol. 42:223-286. pyloric glands are coiled and scattered in Takagi T, Takebayashi S, Tokuyasu K, Tsuji solitary groups (arrows). Bar= 100 µm. K (1974). Scanning electron microscopy on the human gastric mucosa, fetal, normal and various Fig. 21. Pyloric gland region (neck of the pathological conditions. Acta. Pathol. Jap. gland). Luminal surface of pyloric gland cells 24:233-247. is extensively and evenly covered with - Townsend SF (1961). Regeneration of microvilli. Bar= 20 µm. gastric mucosa in rats. Am. J. Anat. 1.Q2.:133- 147. Fig. 22. Pyloric gland region (base of the Vassallo G, Solcia E, Capella C (1969). gland). Lumina l surface of pyloric gland ce 11s Light and electron microscopic i dent i fi cation of is extensively covered with microvi 11i (Mv). Bar several types of endocrine cells in the = 40 µm. gastrointestinal mucosa of the cat. z. Zellforsch. Mikrosk. Anat. 98:333-356. Fig. 23. Pyloric gland. Three G cells with long Vassallo G, Capella C, Solcia E (1971). microvil l i lie in the base of the gland. Bar = 8 Endocrine cells of the human gastric mucosa. z. µm.

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T. Makita: Do you agree with the opinion that the basal portion of the gastric gland. All long microvilli on the G cell's free surface these factors contribute to gastric function, plays a role in the mechanism of cellular therefore, we expect more gastric juice secretion stimulation? If so, are longer microvilli more in man than in the cat, but both are of similar sensitive to stimulation than shorter ones? chemophysiological content. Authors: Yes we agree, refer to Solcia et al. (1967, 1975) (text references) and [Solcia E., J. E. Breazi le: Reference is made to the number Vassallo G., Capella C., (1970). In: Origin, (density) of gastric pits in the different chemistry physiology and pathophysiology of the regions of the stomach. Was there any attempt to gastrointestinal hormones. Grentzfeidt W, (ed.) determine the density through actua 1 counts of Schattauer, Stuttgart p. 3.] One function of gastric pits per unit area of mucosal surface? microvi l l i is to increase the surface area Authors: This paper contains only morphological providing more contact with materials. description of feline stomach. Future results Therefore, longer microvilli would be more will contain quantitative measurement. sensitive to stimulation than shorter ones and can be stimulated by chemicals farther away from J. E. Breazile: Considering the turn over rate the cell plasmalemma. This could allow earlier of gastric epithelial cells, and rate at which transmission of information about glandular they can alter their morpho1 ogy in response to activity. gastric contents, what alterations, if any, would you expect to occur due to the 24 h fast A.W. Stinson: Were the junctional areas between preceding collection of the materials? the cardiac-fundic, fundic-corpus, and corpus Authors: Based on previous studies [Helander HF pyloric regions as distinct as that between the (1986). Ultrastructure of gastric fundus glands gastro-esophageal junction? of refed mice. J. Ultrastruct. Res. 10: 160-175] Authors: No. The gastro-esophageal junction is no major changes were observed in the mucosa. distinct because the mucosal lining is of two The greatest ultrastructural changes are observed different epithelia (stratified and simple in zymogen ce 11s. They show reduced diameter of columnar epithelium). Since the rest of the zymogen granules, the Golgi apparatus occupying a stomach is lined by simple columnar epithelium, smaller area, and the rER having reduced dist i net demarcation between regions of the cisternal space. In the parietal cells there is stomach is not possible. However, different a reduction in the number of microvi 11i and in regions can be identified by the number of the diameter of the intracellular canaliculi. gastric pits and the shape and height of the Other cells should remain unchanged. ridges between gastric pits. J. E. Breazile: You indicate that the diameter of S. Siew: Could you explain what is meant by the gastric pits represent the secretory capacity "rubbing" the mucosa with saline? of the associated gastric glands. Is there any Authors: This method was deve 1oped and described experimental evidence that this association can by Al-Tikriti et al. (1986) (text reference). It be made? is an effective method for cleaning the mucosal Authors: Yes, there is some experimental evidence surface of mucus and cellular debris. The that shows morphological changes of gastric pits. stomach is flushed several times with saline, and It was found that the gastric pits become more the mucosal surface is gently rubbed by the shallow following a meal [Willems G, fingers covered with a surgical glove. The Vansteenkiste Y, Smets P, (1971). Effects of stomach is moderately stretched with the mucosal food ingestion on the cell proliferation kinetics surface up. The edges are pinned to a paraffin in the canine fundic mucosa. Gastroenterology tray. After thorough washing with saline .§1.:323-327]. solution, the stretched stomach is flooded and submerged in the fixative solution. J. E. Breazile: You conclude that less cellular debris, as well as fewer small holes in the S. Siew: In your experience of comparative epithelial cells observed in this study, indicate pathology, are there significant differences a slower turn-over rate of mucosal epithelial between the gastric function of the f e 1i ne cells in the cat than have been observed in man, species and other non-ruminant mamma1s, such as the ferret and the rat. Is it 1i ke ly that the man? method of mucosal preparation for this study Authors: There are histological similarities and contributed to this finding? differences between the feline and human stomach. Authors: The turn-over time has been calculated In both species, the stomach is unilocular and to be between 2 and 8 days for the surface mucous lined by glandular mucosa. However, the mucosa cells and mucous neck cells [Castrup HJ, Fuchs K, differs in thickness: 1 mm in man and Sch i 11er U ( 1973). Zur Ze11 erneuerung der approximately 500 µmin cat (Al-Tikriti and Henry mensch1 i chen magensch1 ei mhaut: Autoradi ograph i che "unpublished data"). The number of gastric in vitro-untessuchungen as magenschleim glands which open into pits are: 3-7 glands in hantbiopsieh. Res. Exp. Med. 161:311-320]. The man [He1 ander HF, ( 1981). The cells of gastric method we used wil 1 get rid ofnearly al 1 mucus mucosa. Int. Rev. Cytol. 70:217-282] and 2-3 and cellular debris but not the holes which should glands in cat [Al-TikriTT (1984.) (text be differentiated from that of artifact origin. reference)]. The distribution of parietal cells However, another possibility is sample in the gastric gland is: in man they are collection. It may be that our samples happened concentrated in the neck and isthmus, whereas in to be from an area that does not show epithelial cat it is not uncommonto find pari eta 1 ce 11s in turnover.

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