Equus Asinus

Pineal gland of donkey Safwat Ebada Morphological and Immunohistochemical Stud- ies on the Pineal Gland of the Donkey (Equus asinus). Safwat Ebada * Department of anatomy and embryology, Faculty of Veterinary Medicine, Mansoura University, Egypt. With 4 figures, 1 table Received August 2011, accepted for publication January 2012 Abstract where the pinealocytes formed 11 The pineal glands of donkey were clusters, widely separated by ag- light beige to dark brown, fusi- gregations of GFAP and S100 Fig (11): Photograph of the lateral surface of the head of the Hooded crow show- form structure. It lies at the pineal ing the site of intra-articular injection of the quadrato-mandibular joint. immunoreactive glial cells and recess caudal to the splenium of their processes. They were also the corpus callosum and cau- striking around blood vessels. At dodorsal to the third ventricle, just the periphery of the gland, only a in front of the rostral colliculi and relatively few GFAP and S100 in between the para hippocampal positive cell bodies and/or pro- gyrus. The pineal gland was sup- cesses were seen in the marginal plied from the caudal choroidal portions of the parenchyma. artery and branches from artery S100 immunoreactive cells show- of corpus callosum. The venous ed similar morphological charac- drainage by the pineal veins flow- teristics to those of GFAP-reac- ing into the cerebral vein. tivity, but their immunoreactivity The glial fibrillary acidic protein was denser. Immunolabeling of (GFAP) and S100 protein immu- the pinealocyte marker synaptophysin was intense, especially in noreactivity was restricted to glial cells. They showed a heteroge- pinealocytes at perivascular neous pattern of immunostaining space. Several highly synapto- 12 for (GFAP) and S100. It was con- physin-positive blotch of variable spicuous around the large pineal extent were a conspicuous fea- ture in pinealocyte throughout the Fig (12): Photograph of the lateral surface of the head of a Cattle egret showing cyst and corpora arenacea, the site of intra-articular injection of the quadrato-mandibular joint gland. While it was less dense in J. Vet. Anat. 47 Vol 5 No 1, (2012) 47 - 74 Pineal gland of donkey Safwat Ebada the vicinity of the pineal cyst and atonin, whereas darkness in- corpora arenacea. The intercellu- creases it (Arendt, 1995). Light lar differences in the degrees of impulses are sent to supra- synaptophysin immunostaining chiasmatic nuclei, in hypothala- may, therefore, reflect different mus, through retinohypothalamic states of a specific cellular activi- tract where the circadian rhythm ty. The presence of synaptophy- of melatonin secretion is regulat- sin in pinealocytes of the normal ed. SCN suppresses the melato- pineal, highlights the paraneu- nin synthesis according to the ronal nature of these cells. amount of light (Arendt 1995; Cagnacci 1996). The mammalian Keywords pineal gland contains two types of parenchymal cells. The pineal- Pineal gland, Immunohistochem- ocytes which form the majority of istry, Synaptophysin, S100, parenchymal cells and responsi- GFAP, Donkey, Equus asinus ble for melatonin secretion in the pineal gland. Glial cells serve as Introduction supporting cells and they are The pineal gland is a neuroendo- fewer in number than pinealo- crine tissue regulates changes cytes (Arendt, 1995 and Kus et exclusively in the functions of the al., 2004). The literature con- endocrine system as well as the tains numerous descriptions of functions of many other systems pineal gland ultrastructure in rat according to light and dark and (Sakai et al., 1996), rabbit (Gar- functions like a biological clock cia and Boya, 1992 b), dog (Cal- along with supra-chiasmatic nu- vo et al., 1990), horse (Cozzi clei. The pineal gland sends time 1986), cow (Sato et al., 1994), signals to other parts of the body and sheep (Regodon et al., 1998 in circadian rhythm through mela- a & b). Pinealocytes play a key tonin hormone. It has an im- role in melatonin secretion in re- portant role, in particular, in con- sponse to sympathetic nerve trol of reproduction functions and stimuli; this gland may therefore in evaluation of seasonal chang- be treated as a neuroendocrine es in day length (Arendt, 1995; organ. In addition to HIOMT (hy- Cagnacci, 1996). Generally, light droxyindoleomethyl transferase), decreases the production of mel- which catalyzes the final step of melatonin biosynthesis, some J. Vet. Anat. 48 Vol 5 No 1, (2012) 47 - 74 Pineal gland of donkey Safwat Ebada neuronal proteins have been de- chased locally and maintained tected in pinealocytes, revealing under recommended husbandry the neuron-like nature of these conditions. The pineal glands cells (Coca et al., 1992, Redeck- were obtained according to the er and Bargsten, 1993). Synap- institutional ethical committee of tophysin (Huang et al., 1992, Re- the Mansoura University, Egypt. decker and Bargsten 1993, Sato et al., 1994). S-100 protein and Anatomy and Histology intermediate filament proteins, After sacrificing the animals, the glial fibrillary acidic protein pineal gland was extracted, fixed (GFAP) are known as glial mark- in bouin’s solution for 24 hours, er proteins in supporting cells of then washed and persevered in the pineal gland in rat, hamster 70% ethanol, the samples were and human (Lopez-Munoz et aI., dehydrated in ascending grades 1992; Borregon et aI., 1993; Bo- of ethanol, cleared in benzene ya and Calvo, 1993). However, and embedded in paraffin wax. the use of neuroendocrine cell Section (5 µm) thickness were markers applied to mammalian stained with iron haematoxylin pinealocytes in general, and a and eosin (H&E), PAS, Alcian glial marker S-100 protein and blue (2.5 PH) and Crossman’s intermediate filament proteins trichrome stains. Processing and (GFAP). Immunoreactivity of staining methods were quoted these antibodies has not been from Bancroft et al. (1996). studied in donkey pineal in the Three donkey's heads were per- available literature. Our goal was fused with a warm normal saline to identify pineal cell types and solution, and then injected with their distribution in adult donkeys an equal mixture of Indian ink via immunohistochemical meth- and bovine serum (1:1) through od using antisera to neuroendo- the Jugular vein and two heads crine cell marker (synaptophysin), were injected with colored latex S100 protein and GFAP. with carmine through the com- mon carotid arteries. The injected Materials and methods specimens were fixed in 10% neutral formalin buffered solution Animals and tissue for 1-2 weeks. Adult, apparently healthy donkeys used in this study were pur- Immunohistochemistry J. Vet. Anat. 49 Vol 5 No 1, (2012) 47 - 74 Pineal gland of donkey Safwat Ebada Monocolonal mouse anti-human ing the protocol of LSAB+kit Glial Fibrillary Acidic Protein (Dako Cytomation, Denmark). (GFAP) (M0761; diluted1:50), After being rinsed in BPS bioti- S100, ready-to-use (N1573; di- nylated secondary antibody luted1:50), rabbit anti human (LASB + Kit; Dako Cytomation, Synaptophysin, (N1566; dilut- Denmark) was applied to the sec- ed1:100), polyclonal rabbit anti- tions for 30 minutes in humidified cow (Dako Cytomation, Den- chamber at room temperature mark) were used for detection of followed by incubation with pe- GFAP, S100 and synaptophysin roxidase-labelled streptavidin for respectively (Table 1). Section of 15 minutes. Bound antibodies (3 µm) thick mounted on slides localization was visualized by in- precoated with polylysine, depar- cubation of the sections with the affinized, rehydrated, and then 3,3 diaminobenzidine (DAB) of incubated for 5 minutes in hydro- the LSAB+Kit solutions (Dako gen peroxide (3% in distilled wa- Cytomation, Denmark). The sec- ter) to reduce endogenous perox- tions were counterstained with idase activity. The slides were Mayer’s haemtoxylin, dehydrated rinsed in phosphate buffer saline and mounted with DPX (Sigma, solution (PBS 7.4 PH), then sub- Munich, Germany). Negative con- sequently heat treated in micro- trol performed by omission of the wave at 750 W for tow cycles of 7 primary antibody. The methods of minutes each in citrate buffer (6 processing and immunohisto- PH) for antigen retrieval. Thereaf- chemical staining were adopted ter the section were allowed to after Kumar and Rudbeck (2009). cool at room temperature for 20 minutes before being rinsed in phosphate buffered saline con- Results taining bovine serum albumen (PH 7.6) for 5 minutes to block Anatomical and Histological nonspecific binding sites. Subse- findings quently, the sections were incu- The pineal glands of donkey, bated with the specific primary were light beige to dark brown in monoclonal antibody for 1 h in a colour and fusiform structure. The humidified chamber at room tem- pineal gland lies at the midline of perature against GFAP and the brain at the pineal recess synaptophysin and S100 follow- J. Vet. Anat. 50 Vol 5 No 1, (2012) 47 - 74 Pineal gland of donkey Safwat Ebada caudal to the splenium of the acidophilic cytoplasm, and a corpus callosum from which it large round nucleus. Glial cells separated by the telachoroidea of nuclei were small darkly stained. the third ventricle, cerebral vein Calcium concretions (corpora ar- and branches of artery of corpus enacea) and pineal cysts of dif- callosum and caudodorsal to the ferent size were a constant fea- third ventricle, just in front of the ture in pineal gland. Pinealocytes rostral colliculi and in between occupied the largest volume of the hippocampus. Weighting ap- the pineal gland. The interstitial proximately 0.1 gm, with an aver- cells were distributed evenly age dimensions, 14 mm dorso- throughout the superficial pineal ventral, 7 mm craniocaudal and 5 gland, but they were more abun- mm thickness. The pineal gland dant around the pineal cyst and was supplied from the posterior corpora arenacea. A relatively choroidal arteries which emanat- large blood vessels were ob- ed from the caudal cerebral arter- served in the connective tissue ies, it receives also pineal bran- capsule, the greater part of blood ches from the artery of corpus vessels were found in the tra- callosum that originates from the becules of the connective tissue, rostral cerebral artery.

Load more