Immunohistochemical study on the ontogenetic development of the regional distribution of peptide YY, pancreatic polypeptide, and glucagon-like peptide 1 endocrine cells in bovine gastrointestinal tract

The regional distribution and relative frequency of peptide YY (PYY)-, pancreatic polypeptide (PP)-, and glucagon-like peptide 1 (GLP-1)-immunoreactive (IR) cells were determined immunohistochemically in the gastrointestinal tract at seven ontogenetic stages in pre- and postnatal cattle. Different frequencies of PYY-, PP-, and GLP-1-IR cells were found in the intestines at all stages; they were not found in the esophagus and stomach. The frequencies varied depending on the intestinal segment and the developmental stage. The frequencies of PYY- and PP-IR cells were lower in the small intestine and increased from ileum to rectum, whereas GLP-1-IR cells were more numerous in duodenum and jejunum, decreased in ileum and cecum, and increased again in colon and rectum. The frequencies also varied according to pre- and postnatal stages. All three cell types were most numerous in fetus, and decreased in calf and adult groups, indicating that the frequencies of these three types of endocrine cells decrease with postnatal development. The results suggest that these changes vary depending on feeding habits and adaptation of growth, secretion, and motility of intestine at different ontogenetic stages of cattle.     

Immunocytochemical identification and localization of peptide hormones in the gastro-entero-pancreatic (GEP) endocrine system of the mouse and a stomachless fish, Barbus conchonius

A large number of antisera mainly raised against mammalian hormones are tested immunocytochemically on the GEP-endocrine system of mouse and fish (Barbus conchonius). The endocrine pancreas of mouse and fish appeared to contain the same four endocrine cell types; insulin-, glucagon-, PP- and somatostatin-immunoreactive cells. In mouse about 13 GEP endocrine cell types are distinguished: 1. insulin-, 2. somatostatin-, 3. glucagon-, 4. PP-, 5. (entero)glucagon-/PP-like, 6. CCK-like, 7. substance P-, 8. neurotensin-, 9. VIP-, 10. gastrin-, 11. secretin-, 12. beta-endorphin-, 13. serotonin-immunoreactive cells. Based on this and a previous study at least 13 GEP endocrine cell types seems to be present in stomachless fish: 1-9 as described for mouse, 10. (entero)glucagon-like, 11. met-enkephalin, 12. VIP-like, 13. unspecific immunoreactive endocrine cells. Coexistence of glucagon and PP-like peptides is found in the gut and pancreas of mice and in the gut of B. conchonius. In mouse pancreas and fish gut, endocrine cells showing only PP- or glucagon-like immunoreactivity are found too. In mouse stomach some endocrine cells showing only PP-immunoreactivity are demonstrated. In the same region coexistence of C-t-gastrin- and FMRF-amide-immunoreactivity is found in endocrine cells. The importance of these phenomena are discussed. Enteric nerves immunoreactive with antisera raised against substance P and GRP are found in mouse, against somatostatin and met-enkephalin in both mouse and fish and against VIP in fish.     

Endocrine cells in the gut of the ascidian Styela clava

Summary Ultrastructural studies have shown the presence of two types of granulated endocrine cell in the gut of Styela clava. Type I, which occurs in the stomach and intestine contains small irregular granules, each with a distinct halo. Type II, found only in the oesophagus contains larger rounded granules, often with little or no halo. The characteristics of these two cell types are compared with those of endocrine cells found in the digestive tracts of other protochordates and discussed with special reference to the evolution of gastrointestinal endocrine cells in vertebrates.The authors are grateful to Mr. R. Jones for photographic assistance. Animals were collected by courtesy of the Admiralty Marine Trials Station, Portsmouth, This research was carried out during the tenure of S.R.C. grant no. B/RG 82919 to one of us (M.C.T.). The localization of polypeptide hormones in the pharynx and gut of protochordates     

Ultrastructural characterization of 6 immunoreactive enteroendocrine cells in Barbus conchonius (Teleostei, Cyprinidae)

Using the semi-thin/ultra-thin technique six different immunoreactive endocrine cell types are ultrastructurally identified in 0.5% glutaraldehyde fixed gut of B. conchonius. In addition two of them (gastrin- and PP-immunoreactive cells) are also characterized with the immunogold method, showing that the immunoreactivity is only restricted to the secretory granules. Size distribution histograms and the average diameters of 30% (d30) of the largest granules are given, showing a gradual increase in granule size from unspecific immunoreactive cells, (d30 = 110 nm) via gastrin- (119 nm), VIP-like- (127 nm), met-enkephalin- (143 nm) and PP- (174 nm) to glucagon-immunoreactive cells (178 nm). The presence of PP- and glucagon-immunoreactivity in the same cells and the consequence for their granule size is discussed. In the distal part of the gut endocrine cells are found showing no immunoreactivity with the antisera used; their granules (d30 = 144 nm) were, although not significantly, larger then those of VIP-like-immunoreactive cells, also found in that part of the gut. It is supposed that they represent substance P-immunoreactive cells. Unfortunately, secretory granules of several cell types showed about 20% more shrinkage in 0.5% glutaraldehyde fixed tissue, than in osmicated tissue.     

Immunocytochemical identification and localization of peptide hormones in the gastro-entero-pancreatic (GEP) endocrine system of the mouse and a stomachless fish,Barbus conchonius

Summary A large number of antisera mainly raised against mammalian hormones are tested immunocytochemically on the GEP-endocrine system of mouse and fish (Barbus conchonius). The endocrine pancreas of mouse and fish appeared to contain the same four endocrine cell types; insulin-, glucagon-, PP- and somatostatin-immunoreactive cells.In mouse about 13 GEP endocrine cell types are distinguished 1. insulin-, 2. somatostatin-, 3. glucagon-, 4. PP-, 5. (entero)glucagon-/PP-like, 6. CCK-like, 7. substance P-, 8. neurotensin-, 9. VIP-, 10. gastrin-, 11. secretin-, 12. -endorphin-, 13. serotonin-immunoreactive cells.Based on this and a previous study at least 13 GEP endocrine cell types seems to be present in stomachless fish: 1–9 as described for mouse, 10. (entero)glucagon-like, 11. met-enkephalin, 12. VIP-like, 13. unspecific immunoreactive endocrine cells.Coexistence of glucagon and PP-like peptides is found in the gut and pancreas of mice and in the gut of B. conchonlus. In mouse pancreas and fish gut, endocrine cells showing only PP-or glucagon-like immunoreactivity are found too. In mouse stomach some endocrine cells, showing only PP-immunoreactivity are demonstrated. In the same region coexistence of C-1-gastrin-and FMRF-amide-immunoreactivity is found in endocrine cells. The importance of these phenomena are discussed.Enteric nerves immunoreactive with antisera raised against substance P and GRP are found in mouse, against somatostatin and met-enkephalin in both mouse and fish and against VIP in fish.In honour of Prof. P. van Duijn     

Immunocytochemical demonstration of vertebrate neuropeptides in the earthworm Lumbricus terrestris (Annelida,Oligochaeta)

Summary The localisation and distribution of 10 vertebrate-derived neuropeptides in the earthworm, Lumbricus terrestris, have been determined by an indirect immunofluorescence technique. The peptides are pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), neuropeptide Y (NPY), glucagon (C-terminal), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), gastrinreleasing peptide (GRP), calcitonin gene-related peptide (CGRP), neurotensin (NT), and met-enkephalin. For 6 of the peptides — PYY, NPY, PHI, glucagon, GRP and CGRP — this is the first demonstration of their presence in any annelid, and NT has not previously been described in an oligochaete. Cell bodies and nerve fibres immunoreactive to the 10 peptides occur throughout the CNS. In the PNS, epidermal sensory cells displayed immunoreactivities to PP and PYY, and PP-, PYY-, NPY-, PHI- and GRP-like immunoreactivities occurred in nerve fibres supplying the main body muscles. Nerve fibres immunoreactive to PP and PYY are also associated with the innervation of the gut (pharynx, oesophageal glands, and mid and posterior regions of the intestine). No endocrine cells immunoreactive for any of the antisera tested could be identified in the gut epithelium, suggesting that dual location of peptides in the brain and gut epithelium is a phenomenon that occurred at a later stage in evolution. No immunoreactive elements were detected in any of the organs and ducts of the reproductive and excretory systems.     

Regeneration of radiation-damaged digestive tissues in juvenile Pacific oysters (Crassostrea gigas)

Juvenile Pacific oysters, Crassostrea gigas, were irradiated with 16 and 40 krad and their tissues examined histologically. Degenerative syndromes and tissue regeneration processes were determined for the stomach, gut, collecting ducts, and digestive tubules. Following degeneration, tissue regeneration was observed in the digestive tissues of most oysters exposed to 16 krad and in a limited number exposed to 40 krad. Regeneration was first observed in the digestive tubules and subsequently in the stomach, gut, and collecting ducts. Cellular repopulation of the digestive tubules involved epithelialization with large, undifferentiated crypt cells which then differentiated into functional secretory and absorptive cells. Regeneration in the stomach, gut, and collecting ducts was initiated by proliferative islands of small basophilic cells. Mitotic division of those cells and their subsequent differentiation into functional epithelial cells resulted in the rapid restoration and apparent recovery of the affected tissues. The results of these studies indicate that radioresistance of juvenile C. gigas may in part be due to the remarkably efficient regenerative mechanisms involved in replacing injured or lost digestive tissues.     

Immunocytochemical investigation of the gastro-entero-pancreatic (GEP) neurohormonal peptides in the pancreas and gastrointestinal tract of the dogfish Squalus acanthias

The pancreas and gastrointestinal tract (GIT) of adults and of an embryonic stage of 11 cm long (about half the length of newborn fish) of the spiny dogfish, Squalus acanthias, were investigated immunocytochemically for the occurrence of the gastro-entero-pancreatic (GEP) neurohormonal peptides. In the pancreas of adult forms 5 endocrine cell types were seen, namely insulin-, somatostatin-, glucagon-, pancreatic polypeptide (PP)- and gastric inhibitory peptide (GIP)-immunoreactive cells. These cell types form scattered islets and were seen sometimes to surround small ducts. GIP-immunoreactivity cells did not occur in glucagon-containing cells. In the mucosa of GIT of adults 18 endocrine cell types were observed, viz. insulin-, somatostatin-, glucagon-, glicentin, PP-, polypeptide YY (PYY)-, vasoactive intestinal polypeptide (VIP)-, GIP-, gastrin C-terminus, CCK-, neurotensin N-terminus-, bombesin/gastrin releasing peptide (GRP)-, substance P-, enkephalin-, alpha-endorphin, beta-endorphin-, serotonin- and calcitonin immunoreactive cells. These cells occurred mostly in the intestine. All these cell types were of the open type, except glucagon- and glicentin-immunoreactive cells in the stomach, which seemed to be of the closed type. In the muscle layers and the submucosa, VIP and substance P- immunoreactive nerves and neurons were observed. In the pancreas of the dogfish embryo only 3 endocrine cell types could be demonstrated, namely insulin-, somatostatin- and glucagon-immunoreactive cells. In the mucosa of the GIT of the embryos studied 12 endocrine cell types were detected, viz. insulin-, somatostatin-, glucagon-, PP-, PYY-, VIP, GIP, gastrin C-terminus-, CCK-, neurotensin N-terminus-, enkephalin- and serotonin immunoreactive cells. The number of these cells, except that of PYY-immunoreactive cells, was lower than that of adults and in some cases their distribution did not correspond with that of adults.     

An immunohistochemical study on the distribution of endocrine cells in the gastrointestinal tract of the musk shrew, Suncus murinus

The endocrine cells in the gastrointestinal tract of the musk shrew were studied immunohistochemically. Eleven kinds of endocrine cells, immunoreactive for serotonin, somatostatin, gastrin, cholecistokinin, gastric inhibitory polypeptide, motilin, secretin, neurotensin, pancreatic glucagon, enteroglucagon and bovine pancreatic polypeptide, were revealed. In the stomach, serotonin-, somatostatin-, gastrin-, pancreatic glucagon- and enteroglucagon-immunoreactive cells were detected. The first three types of cells predominated and were more abundant in the pyloric glands than in the other stomach regions. In the small intestine, all types of endocrine cells were found, each having different distributions and relative frequencies. In the large intestine, 10 types of endocrine cells except cholecystokinin-immunoreactive cells were detected. Serotonin- and bovine pancreatic polypeptide-immunoreactive cells were more numerous in the large intestine than in the small intestine.     

Ghrelin expression in gut endocrine growths

We aimed to assess the occurrence of ghrelin, a new gut hormone, in endocrine growths of the stomach. In addition, since ghrelin has been detected in other gut derivatives during adult and/or fetal life, we also studied endocrine tumours of the pancreas, intestine and lung. A specific serum generated against amino acids 13-28 of ghrelin was tested on 16 specimens of gastric mucosa with endocrine cell hyperplasia and on 75 endocrine tumours. Ghrelin-immunoreactive cells were moderately represented in normal, atrophic or hypertrophic gastric mucosa, as a rule with no obvious hyperplastic changes even in the presence of concurrent, prominent enterochromaffin-like cell hyperplasia associated with hypergastrinemia. Ghrelin cells were also found in tumour cell fractions of well-differentiated gastric (25 of 33, 76%), pancreatic (6 of 15, 40%) and pulmonary (4 of 8) endocrine tumours. No ghrelin immunoreactivity was detected in 14 intestinal tumours and in five poorly differentiated endocrine carcinomas of the stomach or pancreas. We conclude that ghrelin cells may take part in gut endocrine growths, with special reference to well-differentiated endocrine tumours of the stomach, independently from associated signs of endocrine hyperfunction.     

Gastrointestinal hormones in birds: morphological, chemical, and developmental aspects

Historically, the enterochromaffin cell was the first endocrine cell type detected in avian gut; subsequently, a number of types of such cells were distinguished on the basis of the ultrastructural features of the secretory granules. More recently, immunocytochemical procedures have revealed somatostatin-, pancreatic polypeptide (PP)-, polypeptide YY-, glucagon-, secretin-, vasoactive intestinal peptide (VIP)-, gastrin-, cholecystokinin-, neurotensin-, bombesin-, substance P-, enkephalin-, motilin-, and FMRFamide-like immunoreactivity in avian gastrointestinal endocrine cells. Most endocrine cells are located in the antrum; there are a number in the proventriculus and small intestine but few in the gizzard, cecum, and rectum. Several avian gastroenteropancreatic hormones, including glucagon, VIP, secretin, bombesin, neurotensin, and PP, have been isolated and sequenced. They resemble the equivalent mammalian peptides in terms of molecular size but differ in amino acid composition and sequence; some (e.g., VIP) differ only in minor respects, others (e.g., secretin) more radically. Gastrointestinal endocrine cells appear late in development; available data indicate that few types are recognized by either immunocytochemistry or electron microscopy before 16 days of incubation. Experimental evidence has shown that at least the majority of gut endocrine cells are of endodermal origin and are not derived from the neural crest or neuroectoderm as earlier proposed. In early embryos, the progenitors of gastrointestinal endocrine cells are more widespread than are the differentiated cells in chicks at hatching. This, along with other observations, raises the question of factors that might influence the differentiation of gut endocrine cells.     

两种有胃鱼消化道6种内分泌细胞的免疫组织化学比较研究

目的 应用6种胃肠激素抗血清对胡子鲶(Clarias fuscas)和瓦氏黄颡鱼(Pelteobagrus vachelli Richardson)消化道内分泌细胞进行了免疫组织化学比较.方法 应用链霉亲和素-生物素-过氧化物酶复合物技术(streptavidin biotin-peroxidase complex method,SABC法)免疫组织化学方法.结果 除胡子鲶后肠外,五羟色胺细胞在两种鱼的消化道各段均有分布,其中贲门部或幽门部密度最高,前中肠次之,食道最少;胡子鲶消化道中生长抑素细胞主要分布于胃贲门部和胃部,食管、胃幽门及肠道内未见分布,而瓦氏黄颡主要分布于食管和胃部,肠道内未见分布;胃泌素细胞在胡子鲶消化道内只在肠内检测到,瓦氏黄颡只在幽门胃和前肠两个部位检测到;胰多肽细胞只在瓦氏黄颡的幽门胃和前肠两个部位有分布;胰高血糖素和P-物质两种细胞在两种鱼的消化道各段均未见其分布.结论 两种有胃鱼消化道中六种内分泌细胞的分布既有一定的共性,体现了两者消化生理的共同点;同时又存在较大的种间差异,与各自食性及生活环境相适应.     

Chromogranins A and B and secretogranin II in hormonally identified endocrine cells of the gut and the pancreas

Chromogranins A and B and secretogranin II have been localized in a wide spectrum of gastroenteropancreatic endocrine/paracrine cells. Chromogranin A immunoreactivity showed the widest distribution and was displayed by glucagon-, PP-, gastrin-, gastrin-CCK-, secretin-immunoreactive cells, the most intense stainings being peculiar of enterochromaffin cells. Chromogranin B immunoreactivity was detected in gastrin- and glucagon cells and in some enterochromaffin cells containing also chromogranin A. Secretogranin II was paired to chromogranin A in glucagon cells of pancreatic islets or occurred alone in glycentin/PP cells of colonic mucosa. Neither of the chromogranins nor secretogranin II have been so far detected in somatostatin-, GIP-, or motilin-immunoreactive cells. Chromogranin A but not chromogranin B or secretogranin II has been detected in the gastric argyrophilic ECL cells.     

Functional morphology of the developing alimentary canal in the holothurian Eupentacta fraudatrix (Holothuroidea, Dendrochirota)

Development of the digestive tract of the holothurian Eupentacta fraudatrix was examined using light and transmission electron microscopy. After the blastopore closes, the gut rudiment loses its connection with the blastoderm and becomes an enclosed, tubular chamber, ending blindly at both ends. The differentiation of the digestive and coelomic epithelia is mainly completed by day 12. Since no transient cell types are observed, this differentiation is definitive. By day 20, the mouth and anal openings appear. The cuticular lining in the anterior part of the gut rudiment has an endodermal origin and differentiates before the mouth is formed. The rest of the gut lining is composed of enterocytes typical of holothuroid intestine. At the early stages of development, mitotic figures are encountered among nonspecialized cells of the gut primordium. In more developed digestive epithelium, vesicular enterocytes are capable of mitotic division. Dividing enterocytes retain secretory vacuoles; thus mitosis occurs in actually differentiated cells. After mouth and anus formation, the oesophagus, stomach, intestine and rectum can be distinguished. In the wall of the stomach, powerful musculature is formed.     

Neuropeptides in the gastrointestinal canal of Necturus maculosus

Summary The presence and distribution of regulatory peptides in nerves and endocrine cells of the stomach, intestine and rectum of a urodele amphibian, the mudpuppy, Necturus maculosus, was studied immunohistochemically in sections or whole-mount preparations of the gut wall. The effect of the occurring peptides on gut motility was studied in isolated strip preparations of circular and longitudinal smooth muscle from different parts of the gut.Bombesin-, neurotensin-, substance P- and VIP-like immunoreactivity was present in abundant nerve fibres in the myenteric plexus of both stomach, intestine and rectum. Single fibres or bundles were present in the circular muscle layer and in a well-developed deep muscular plexus in the intestine and rectum. Immunoreactive nerve cells were found in the myenteric plexus of the stomach, intestine (neurotensin only) and rectum. Gastrin/CCK-like immunoreactivity was observed only in a few fibres in stomach and rectum.Endocrine cells containing bombesin-, met-enkephalin-, gastrin/CCK-, neurotensin-, somatostatin- or substance P- like immunoreactivity were present in the mucosa.The effect of bombesin was an inhibition of the rhythmic activity in circular muscle preparations and in longitudinal muscle from the rectum, while longitudinal muscle from the stomach usually responded with a weak increase in tonus. Neurotensin, like bombesin, was inhibitory on the spontaneous rhythmic activity of circular muscle throughout the gut, while the effect on longitudinal muscle was an increase in tonus. Met-enkephalin and substance P increased the tonus of all types of preparations, and often, in addition, initiated a rhythmic activity superimposed on this maintained tonus. VIP had a general inhibitory effect on the preparations, decreasing tonus and/or abolishing rhythmic activity.It is concluded that bombesin-, neurotensin-, substance P- and VIP-like peptides are present in nerves throughout the urodele gut and may have physiological functions in regulating the motility of the gut. The gastrin/CCK-like peptide present in nerves of the stomach and rectum may affect the function of these parts of the gut. The regulatory peptides present in endocrine cells may, perhaps with the exception of the somatostatin-like peptide, affect the motility humorally.     

Immunocytochemical investigation of the gastro-enteropancreatic (GEP) neurohormonal peptides in the pancreas and gastrointestinal tract of the dogfishSqualus acanthias

Summary The pancreas and gastrointestinal tract (GIT) of adults and of an embryonic stage of 11 cm long (about half the length of newborn fish) of the spiny dogfish,Squalus acanthias, were investigated immunocytochemically for the occurrence of the gastro-entero-pancreatic (GEP) neurohormonal peptides. In the pancreas of adult forms 5 endocrine cell types were seen, namely insulin-, somatostatin-, glucagon-, pancreatic polypeptide (PP)- and gastric inhibitory peptide (GIP)-immunoreactive cells. These cell types form scatterd islets and were seen sometimes to surround small ducts. GIP-immunoreactivity cells did not occur in glucagon-containing cells. In the mucosa of GIT of adults 18 endocrine cell types were observed, viz. insulin-, somatostatin-, glucagon-, glicentin-, PP-, polypeptide YY (PYY)-, vasoactive intestinal polypeptide (VIP)-, GIP-, gastrin C-terminus, CCK-, neurotensin N-terminus-, bombesin/gastrin releasing peptide (GRP)-, substance P-, enkephalin-, -endorphin, -endorphin-, serotonin- and calcitonin immunoreactive cells. These cells occurred mostly in the intestine. All these cell types were of the open type, except glucagon- and glicentin-immunoreactive cells in the stomach, which seemed to be of the closed type. In the muscle layers and the submucosa, VIP and substance P-immunoreactive nerves and neurons were observed. In the pancreas of the dogfish embryo only 3 endocrine cell types could be demonstrated, namely insulin-, somatostatin- and glucagon-immunoreactive cells. In the mucosa of the GIT of the embryos studied 12 endocrine cell types were detected, viz. insulin-, somatostatin-, glucagon-, PP-, PYY-, VIP, GIP, gastrin C-terminus-, CCK-, neurotensin N-terminus-, enkephalin- and serotonin immunoreactive cells. The number of these cells, except that of PYY-immunoreactive cells, was lower than that of adults and in some cases their distribution did not correspond with that of adults.     

白条草蜥消化道内分泌细胞的免疫组织化学

应用6种胃肠激素抗血清和免疫组织化学ABC法(avidin-biotin complex method),对白条草蜥(Takydromus wolteri)消化道内分泌细胞进行了免疫组织化学定位研究和形态学观察。结果表明,5-羟色胺细胞较其他5种内分泌细胞的分布更为广泛,整个消化道中(即从食管到直肠)均有分布,其分布密度高峰位于幽门。食管、回肠和直肠未检测到生长抑素细胞,生长抑素细胞在幽门部分布密度最高,总体来说生长抑素细胞的分布在胃部较高而在小肠部较低。胃泌素细胞和胰多肽细胞分布在小肠,均在十二指肠分布密度最高。胰高血糖素细胞在胃幽门部分布密度最高,十二指肠、空肠次之,回肠分布密度最低。P-物质细胞仅分布于幽门部。6种内分泌细胞以圆形和锥体形为主,它们广泛分布于消化道黏膜之间、腺泡上皮细胞之间及上皮细胞基部。内分泌细胞的密度分布与其食性、食物组成和生活环境有关,它们的形态与其内、外分泌功能是相适应的。     

Distribution of endocrine cells in the digestive tract of Alligator sinensis during the active and hibernating period

The digestive tract is the largest endocrine organ in the body; the distribution pattern of endocrine cells varies with different pathological and physiological states. The aim of the present study was to investigate the distributed density of 5-hydroxytryptamine (5-HT), gastrin (GAS), somatostatin (SS) and vasoactive intestinal peptide (VIP) immunoreactive (IR) cells in the digestive tract of Alligator sinensis during the active and hibernating period by immunohistochemical (IHC) method. The results indicated that 5-HT-IR cells were distributed throughout the entire digestive tract, which were most predominant in duodenum and jejunum. The density increased significantly in stomach and duodenum during hibernation. GAS-IR cells were limited in small stomach and small intestine. The density decreased significantly in small stomach during hibernation, while increased in duodenum. What's more, most of the endocrine cells in duodenum were generally spindle shaped with long cytoplasmic processes ending in the lumen during hibernation. SS-IR cells were limited in stomach and small stomach. The density increased in stomach while decreased in small stomach during hibernation, meanwhile, fewer IR cells occurred in small intestine. VIP-IR cells occurred in stomach and small stomach. The density decreased in small stomach, while increased in stomach during hibernation. These results indicated that the endocrine cells in different parts of digestive tract varied differently during hibernation, their changes were adaptive response to the hibernation.     

An immunohistochemical survey of endocrine cells and nerves in the proximal small intestine of the platypus,Ornithorhynchus anatinus

The relative frequencies of endocrine cells and peptidergic nerve elements in the proximal small intestine of the adult platypus were studied by immunohistochemistry. Six kinds of endocrine cells - serotonin (5-HT)-, somatostatin-, gastrin-, motilin-, cholecystokinin (CCK)- and bovine pancreatic polypeptide (BPP)-immunoreactive cells - were identified in this study. These endocrine cells were found most frequently in the intestinal glands, in moderate numbers in the tubular ducts and were infrequent in the surface folds. 5-HT-immunoreactive cells were most numerous, somatostatin-, gastrin-, motilin- and BPP-immunoreactive cells were moderately numerous, whereas CCK-immunoreactive cells were rare. Five kinds of neuropeptides: substance P, vasoactive intestinal polypeptide (VIP), gastrin releasing peptide (GRP), somatostatin and leu-enkephalin, were detected in the intramural nerve elements. Substance P-, VIP- and GRP-immunoreactive nerve fibers were found most frequently in the lamina propria mucosae of the surface folds. The relationships between the possible functions of the peptides and amine detected in this study as well as the characteristic structure of the digestive tract of the adult platypus are discussed.     

An immunohistochemical study on the distribution of endocrine cells in the chicken gastrointestinal tract

The distribution and the frequency of occurrence of nine types of gut endocrine cells were revealed using immunohistochemical methods in eight portions from the gastrointestinal tract of the chicken (Gallus gallus var domestica). In the proventriculus, somatostatin- and gastrin-releasing polypeptide (GRP)-immunoreactive cells were commonly found. Serotonin-, pancreatic glucagon-, and enteroglucagon-immunoreactive cells were uncommon. Avian pancreatic polypeptide (APP)-immunoreactive cells were rare. In the gizzard, numerous GRP-, and a small number of somatostatin-immunoreactive cells were observed. The pyloric region was characterized by the presence of abundant gastrin-, somatostatin-, and neurotensin-immunoreactive cells. Numerous serotonin-immunoreactive cells were detected in all portions of the intestine. Moderate numbers of neurotensin-immunoreactive cells were detected in all portions of the intestine except for the cecum. A few gastrin- and somatostatin-immunoreactive cells were detected in the duodenum and jejunum. A small number of pancreatic glucagon-immunoreactive cells were detected in the jejunum and ileum. Enteroglucagon-immunoreactive cells were detected in the small intestine in increasing numbers forwards the ileum. Motilin-immunoreactive cells were rare in the small intestine.