An immunohistochemical study of the pancreatic endocrine cells of the nude mouse, Balb/c-nu/nu

The regional distribution and frequency of the pancreatic endocrine cells in the nude mouse, Balb/c-nu/nu were studied by immunohistochemical (peroxidase anti-peroxidase; PAP) methods using specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (hPP). The pancreas of the mouse was divided into two lobes, the splenic and duodenal lobes, and each lobe was subdivided into three regions, the pancreatic islets (central and peripheral regions), the exocrine region and the pancreatic duct region (consisting of duct epithelium and surrounding connective tissue--sub-epithelial connective tissue). In the pancreatic islets, most of insulin-immunoreactive (IR) cells were located in the central region, and glucagon-, somatostatin and hPP-IR cells were located in the peripheral region regardless of the lobe. In the splenic part, glucagon-IR cells were also located in the central regions, and more numerous somatostatin-IR cells were detected in the central regions compared to those of the duodenal part. hPP-IR cells were restricted to the peripheral regions in both lobes but more numerous cells were detected in the duodenal portion as compared to those of the splenic portion. In the exocrine parenchyma of the splenic lobe, only insulin-, glucagon- and somatostatin-IR cells were detected.. Here, the insulin- and glucagon-IR cells formed cell clusters, while somatostatin-IR cells were present as solitary cells. In the exocrine region of the duodenal portion, only insulin-, somatostatin- and hPP-IR cells were observed, with the same distributional pattern as that found in the splenic lobe. However, clusters of cells consisting only of hPP-IR cells were distributed in the pancreas parenchyma as small islets. In the pancreatic duct region, only solitary hPP-IR cells were demonstrated in the sub-epithelial connective tissue regions of the splenic portion. In conclusion, some strain-dependent characteristic distributional patterns of pancreatic endocrine cells, especially of the hPP-IR cells, were found in the nude mouse. In addition, somewhat different distributional patterns were found between the two pancreatic lobes.     

Distribution and frequency of endocrine cells in the pancreas of the ddY mouse: an immunohistochemical study

The regional distribution and frequency of pancreatic endocrine cells in ddY mice were studied by an immunohistochemical (peroxidase anti-peroxidase; PAP) method using four types of specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (hPP). In the pancreatic islets, most of insulin-immunoreactive (IR) cells were located in the central portion. Most of glucagon- and somatostatin-IR cells were observed in peripheral regions although a somewhat smaller number of cells were also located in the central regions. HPP-IR cells were randomly distributed throughout the entire islets. In the exocrine pancreas, insulin-, glucagon-, somatostatin- and hPP-IR cells were detected; they occurred mainly among the exocrine parenchyma as solitary cells. Cell clusters consisted of only insulin- or only glucagon-IR cells and were distributed in the pancreas parenchyma as small islets. In addition, insulin- and glucagon-IR cells were also demonstrated in the pancreatic duct regions. Insulin-IR cells were located in the epithelium and sub-epithelial connective tissue regions as solitary cells and/or clusters (3-4 cells), and glucagon-IR cells were mainly located in the epithelium as solitary cells. Overall, there were 63.89+/-5.39% insulin-, 26.52+/-3.55% glucagon-, 7.25+/-2.83% somatostatin- and 1.90+/-0.58% hPP-IR cells. In conclusion, some strain-dependent characteristic distributional patterns of pancreatic endocrine cells were found in the ddY mouse.     

The distribution and frequency of endocrine cells in the splenic lobe of grass lizard (Takydromus wolteri). An immunohistochemical study

The regional distribution and frequency of the pancreatic endocrine cells in the splenic lobe of grass lizard, Takydromus wolteri, were studied by immunohistochemical (PAP) method using six types of specific mammalian antisera against bovine Sp-1/chromogranin (bCG), serotonin, insulin, glucagon, somatostatin and human pancreatic polypeptide (hPP). The pancreas was subdivided into two regions--islet kike and exocrine regions. The frequency of each immunoreactive (IR) endocrine cells was calculated as mean number/total 100 islet cells and as mean number/total 1,000 cells (including exocrine and endocrine cells) using automated image analysis process. In addition, the percentage of each IR cell was also calculated. All of six endocrine cells were demonstrated. They were dispersed in the whole pancreatic parenchyma between exocrine acinar cells, or they were also observed as islet like clusters. In islet-like regions, bCG-, insulin- and glucagon-IR cells were detected as one or two cell layer cords and they were located between this cell-cords with 14.30+/-5.62, 61.50+/-9.76 and 26.50+/-9.31/100 cells frequencies, respectively. However, somatostatin-IR cells were mainly located in the peripheral parts not in cell-cords with 12.40+/-4.86/100 cells, and no serotonin- and hPP-IR cells were demonstrated. In exocrine regions, all of bCG-, serotonin-, insulin-, glucagon-, somatostatin- and hPP-IR cells were detected and they occurred mainly among the exocrine parenchyma as solitary cells with 10.30+/-2.54, 0.80+/-0.63, 15.50+/-5.30, 5.80+/-2.66, 3.10+/-1.29 and 11.00+/-3.33/1000 cells frequencies, respectively. In addition, serotonin-IR cells were mainly located between epithelia and connective tissue of pancreatic duct. Overall, there were 0.58+/-0.49% serotonin-, 56.44+/-9.35% insulin-, 23.73+/-8.22% glucagon-, 11.28+/-3.03% somatostatin- and 7.97+/-2.02% hPP-IR cells.     

Histological and immunohistochemical studies of the endocrine pancreas of lizards

The endocrine pancreas of the grass lizard, Mabuya quinquetaenia-ta, and of the desert lizard, Uromastyx aegyptia, was investigated histologically and immunohistochemically. In both lizard species four cell types were observed in the endocrine pancreas, namely insulin (B), glucagon (A), somatostatin (D) and pancreatic polypeptide (PP) cells. In both species in B, A and D cells could be detected by their cross-reactivity with antisera raised against mammalian insulin, glucagon and somatostatin. However, these cells showed different tinctorial propertis in the two lizard species. In both species the endocrine tissues were concentrated in the splenic lobe of the pancreas. In the grass lizard the endocrine tissue in the splenic lobe of consisted mainly of B, A and D cells and in the ventral lobe the major cell types were PP and D cells. In the desert lizard, on the other hand, the frequency and the pattern of orientation of B, A and D cells were the same in both the splenic and the ventral lobes, but PP cells in the ventral lobe outnumbered those of the splenic lobe. The PP and D cells scattered in the exocrine parenchyma and the long protrusions which they exhibited suggested that these cell exerted paracrine control on the acinar cells. It is speculated that this control by PP cells may be trophic and by D cells inhibitory.     

Histological and immunohistochemical studies of the endocrine pancreas of lizards

Summary The endocrine pancreas of the grass lizard, Mabuya quinquetaeniata, and of the desert lizard, Uromastyx aegyptia, was investigated histologically and immunohistochemically. In both lizard species four cell types were observed in the endocrine pancreas, namely insulin (B), glucagon (A), somatostatin (D) and pancreatic polyeptide (PP) cells. In both species the B, A and D cells could be detected by their cross-reactivity with antisera raised against mammalian insulin, glucagon and somatostatin. However, these cells showed different tinctorial properties in the two lizard species. In both species the endocrine tissues were concentrated in the splenic lobe of the pancreas. In the grass lizard the endocrine tissue in the splenic lobe consisted mainly of B, A and D cells and in the ventral lobe the major cell types were PP and D cells. In the desert lizard, on the other hand, the frequency and the pattern of orientation of B, A and D cells were the same in both the splenic and the ventral lobes, but PP cells in the ventral lobe outnumbered those of the splenic lobe. The PP and D cells scattered in the exocrine parenchyma and the long protrusions which they exhibited suggested that these cells exerted paracrine control on the acinar cells. It is speculated that this control by PP cells may be trophic and by D cells inhibitory.     

An immunohistochemical study of endocrine cells in the pancreas of the Red-bellied frog (Bombina orientalis)

The regional distribution and frequency of pancreatic endocrine cells in the red-bellied frog, Bombina orientalis, were studied by the immunohistochemical peroxidase anti-peroxidase (PAP) method using five types of specific mammalian antisera to insulin, glucagon, somatostatin, bovine pancreatic polypeptide (PP) and secretin. The frequency was calculated as the mean number of each endocrine cell type/1,000 total cells (including exocrine and endocrine cells) using an automated image analysis process. The percentage of each immunoreactive (IR) cell species to the total IR cell population was also calculated. In the pancreas of the red-bellied frog, all five endocrine cell types were demonstrated. Insulin IR cells were located in the pancreas as single cells or islet-like clusters. The latter were localized in central regions. The insulin-IR cells showed a frequency of 65.40 plus/minus 14.56/1,000 cells. Glucagon IR cells were also detected as single cells or as clusters but in the case of clusters, two distributional patterns were detected - a central core type and a marginally distributed type. They showed an abundance of 32.70 plus/minus 7.32/1,000 cells. Somatostatin-IR cells were dispersed throughout the pancreatic parenchyma as single cells, three to four cells, or clusters. The clusters were located in the marginal regions. The somatostatin-IR cell frequency was 19.40 plus/minus 6.52/1000 cells. PP-IR cells were randomly distributed throughout the pancreatic parenchyma as single cells with a frequency of 14.70 plus/minus 4.92/1,000 cells. Secretin-IR cells were demonstrated as clusters or as single cells, and as clusters they occupied the central regions. They showed a frequency of 39.60 plus/minus 10.36/1,000 cells. This is the first report of the presence of secretin-IR cells in amphibian pancreatic endocrine cells. Overall, there were 37.20 plus/minus 6.84% insulin-, 21.90 plus/minus 5.55% glucagon-, 11.60 plus/minus 4.33% somatostatin-, 8.60 plus/minus 2.72% PP- and 23.40 plus/minus 4.45% secretin-IR cells.     

Changes in gastric endocrine cells in Balb/c mice bearing CT-26 carcinoma cells: an immunohistochemical study

The distribution and density of gastric endocrine cells in Balb/c mice bearing CT-26 carcinoma cells were studied immunohistochemically employing specific antisera against serotonin, somatostatin, glucagon, gastrin, cholecystokinin (CCK)-8 and human pancreatic polypeptide (hPP). The animals were divided into two groups, a non-implanted sham group and a CT-26 carcinoma cell-implanted group. Samples were collected from two regions of the stomach (fundus and pylorus) at 28 days after implantation of the medium or the CT-26 cells (1x10(5) cells/mouse). Five of the 6 types of immunoreactive (IR) cells were identified, with only the hPP IR cells not being detected. The regional distribution of the gastric endocrine cells in the CT-26 implanted group was similar to that of the non-implanted sham group. However, the endocrine cells were significantly decreased in the CT-26-implanted group as compared to those of the non-implanted sham group. Serotonin- and somatostatin-IR cells in the fundus and pylorus , and gastrin- and CCK-8-IR cells in the pylorus of the CT-26 implanted groups were significantly decreased compared to those of the sham group. In addition, glucagon-IR cells were restricted only to the fundus of the sham animals. hPP-IR cells were not detected in either the T-26 implanted- or the non-implanted group. Since endocrine cells are the anatomical units responsible for the production of gut hormones, a change in their density may reflect a change in their capacity to produce such hormones. Implantation of the tumor cell mass induced severe quantitative changes in gastric endocrine cell density, an abnormality which may contribute to the development of gastrointestinal symptoms, such as anorexia and indigestion, frequently encountered in cancer patients.     

An immunohistochemical study of pancreatic endocrine cells in SKH-1 hairless mice

The regional distribution and frequency of the pancreatic endocrine cells in the SKH-1 hairless mouse were studied by an immunohistochemical (peroxidase anti-peroxidase; PAP) method using four types of specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (PP). The pancreas of mice were divided into three portions; pancreatic islets, exocrine and pancreatic ducts. The pancreatic islets were further subdivided into three regions (central, mantle and peripheral region) according to their located types of immunoreactive cells. In the pancreatic islet portions, insulin-immunoreactive cells were located in the central and mantle regions with 84.60 +/- 7.65 and 33.00 +/- 12.45/100 cells frequencies, respectively, but most of somatostatin-, glucagon- and PP-immunoreactive cells were detected in the mantle and peripheral regions. In the mantle region, somatostatin-, glucagon- and PP-immunoreactive cells were demonstrated with 28.70 +/- 9.91, 52.00 +/- 14.05 and 2.60 +/- 1.51/100 cells frequencies, respectively, and showed 6.20 +/- 2.86, 15.30 +/- 5.31 and 21.50 +/- 10.28/100 cells frequencies, respectively in peripheral regions. However, glucagon-immunoreactive cells were also demonstrated in the central regions with 4.00 +/- 2.83/100 cells frequency. In the exocrine portions, insulin-, glucagon-, somatostatin- and PP-immunoreactive cells were demonstrated in the SKH-1 mouse with 0.90 +/- 0.74, 0.80 +/- 0.79,4.90 +/- 3.54 and 2.70 +/- 1.34/100 cells frequencies, respectively. In the pancreatic duct portions, insulin-, glucagon- and somatostatin-immunoreactive cells were demonstrated in the subepithelial connective tissues and showed islet-like appearances with 30.30 +/- 14.67, 2.70 +/- 3.13 and 5.90 +/- 4.23/100 cells frequencies, respectively. However, no PP-immunoreactive cells were demonstrated in these regions. In conclusion, some peculiar distributional patterns of pancreatic endocrine cells were found in the SKH-1 hairless mouse.     

A light-microscopic immunocytochemical study of the endocrine pancreas in the Australian brush-tailed possum (Trichosurus vulpecula).

The endocrine pancreas of the Australian brush-tailed possum (Trichosurus vulpecula) was investigated by means of immunocytochemistry using the avidin-biotin-peroxidase technique. This was a light microscopic study using this established technique. Serial paraffin sections were stained individually with primary antibodies for glucagon, insulin, somatostatin, and pancreatic polypeptide (PP), showing the same islet. Cells immunoreactive to glucagon, insulin, somatostatin and PP were found in endocrine islets. PP cells appear to be scattered amidst the exocrine portion also. Insulin immunoreactive cells were located in the central region of islet, glucagon in the periphery, somatostatin in periphery and had elongated processes. PP cells were more sparse and located both in the periphery of islet and amidst the exocrine tissue. These results can then be related to a similar study in the same marsupial, but using the immunofluorescence technique and to studies in other marsupials such as grey kangaroo (Macropus fuliginosus) fat-tailed dunnart (Sminthopsis crasicaudata) and the American opossum (Didelphis virginiana). These investigations are part of a study in Australian mammals.     

An immunohistochemical study of the insulin-, glucagon- and somatostatin-immunoreactive cells in the developing pancreas of the chicken embryo

The distributions and relative frequencies of insulin-, glucagon- and somatostatin-immunoreactive cells were studied in dorsal, ventral, third and splenic lobes of developing chicken pancreas during embryonic periods (10 days of incubation to hatching) by immunohistochemical methods. The regions of pancreas were subdivided into three regions: exocrine, light and dark islet. Round, oval and spherical shaped immunoreactive cells were detected in all four lobes. According to developmental stages, the types of lobes and the regions of pancreas showed various distributions and relative frequencies. In the splenic lobes, insulin, glucagon and somatostatin-immunoreactive cells were detected in exocrine, dark islet and light islet from time differentiation of splenic lobes, 13 days of incubation. The insulin- and somatostatin-immunoreactive cells of the third lobes were detected in exocrine and light islets from 10 days of incubation, and in dark islets from 15 and 11 days of incubation respectively. Glucagon-immunoreactive cells were detected in exocrine, dark and light islets from 16, 11 and 19 days of incubation respectively. These immunoreactive cells of the ventral lobes were detected in exocrine and light islets. However, dark islets were not found in this lobe. Insulin-immunoreactive cells were demonstrated from 10 days of incubation in these two regions. Glucagon-immunoreactive cells were detected from 17 days of incubation in exocrine and 16 days of incubation in the light islets. Somatostatin-immunoreactive cells were demonstrated from 11 days of incubation in exocrine and 14 days of incubation in the light islets. In the dorsal lobes, insulin-immunoreactive cells were demonstrated in exocrine, dark and light islets from 12, 14, and 13 days of incubation, respectively. Glucagon- and somatostatin-immunoreactive cells were detected in dark and light islets from 13 and 14 days of incubation, respectively. Glucagon- and somatostatin-immunoreactive cells were demonstrated from 10 and 11 days of incubation in exocrine respectively. Generally, insulin-immunoreactive cells were increased in light islets but decreased in light islets with developmental stages. However, glucagon-immunoreactive cells were decreased in light islets but increased in dark islets. In addition, somatostatin-immunoreactive cells showed the same frequencies in light and dark islets with developmental stages except exocrine which increased with developmental stages.     

Development of the endocrine cells in the rat pancreatic and bile duct system

Summary Morphological features of the endocrine cells in the duct system of the pancreas and the biliary tract have been recently characterized in the adult animal with respect to their physiological roles. In the present study, we have investigated their chronological appearance as well as their developmental progress at various stages of the rat fetal and postnatal life. On day 12 of gestation, glucagon and insulin, as well as CCK cells, were identified in the pancreatic primordium. On day 14, glucagon and CCK cells were first detected in the epithelial lining of the common hepatic and the hepatic ducts. These cells remained the dominant endocrine type in the duct system during the fetal period. Insulin and pancreatic polypeptide cells were first observed in the common hepatic duct only on days 16 and 18 of gestation respectively. In spite of their presence in the islets, somatostatin cells were not detected in the duct system during fetal life. They started to appear in the accessory pancreatic duct of the neonate, and subsequently in the common hepatic duct as well as in the small pancreatic ones on day 7 after birth. During postnatal development, the endocrine cells showed progressive or retrogressive changes in different portions of the duct system according to the cell type. In general, somatostatin, CCK and pancreatic polypeptide cells showed an increase, while glucagon and insulin cells gradually dwindled in number up to the adult stage. Somatostatin cells exhibited a significant increase in number, becoming the highest population among the duct endocrine cells in the adult. Throughout the developmental progress, the endocrine cells appear to be allocated in regions relevant to their possible influence modulating the exocrine secretion as well as the drainage of the pancreatic and bile fluid. To whom correspondence should be address.     

An immunocytochemical investigation with monoclonal antibodies to somatostatin

Summary Four monoclonal antibodies specific for somatostatin have been produced and characterized. These antibodies were used to assess the anatomical relationship of somatostatin-containing cells in the pancreas and gastrointestinal tract of man, baboon and rat with ten other peptide-containing endocrine cells. The peptides investigated were gastrin, cholecystokinin, motilin, secretin, neurotensin, gastric inhibitory polypeptide, gut-glucagon, pancreatic glucagon, pancreatic polypeptide and insulin.The only regions in which somatostatin cells were seen in close contact with another endocrine cell were in the pancreas and the gastric antrum. In the pancreas somatostatin cells were commonly seen in close contact with insulin, glucagon and pancreatic polypeptide cells and infrequent contact was demonstrable with the gastrin-immunoreactive cells in the antrum of both rat and man. In all other cases no evidence was obtained for a close anatomical relationship between somatostatin cells and the other enteroendocrine cells.     

Identification of cell types containing S-100b protein-like immunoreactivity in the islets of Langerhans of the guinea pig pancreas with light and electron microscopy

Summary Cell types containing S-100b protein-like immunoreactivity in the islets of Langerhans of the guinea pig were studied by light- and electron-microscopic immunocytochemistry using antisera to S-100b protein, insulin, glicentin, somatostatin, and pancreatic polypeptide. Two types of S-100b-immunoreactive cells were identified. The first type was stellate and characterized by thin cytoplasmic processes sheathing endocrine-type cells, especially pancreatic A-cells. It was located predominantly in the neuro-insular complex and in large islets, both of which were located near the main pancreatic duct. Intense immunoreactivity was found in the cytoplasmic matrix as well as in the nucleoplasm. Nerve fibers or endings were occasionally ensheathed by its cytoplasmic processes. The second type, whose immunoreactivity was rather weak and varied from one cell to another, was oval to polygonal in shape and located randomly throughout the islets. It was an endocrine cell-type and its immunoreactivity was located in the secretory granule. With the use of immunostained consecutive sections for demonstrating pancreatic endocrine cell-types, it was found that a portion of the pancreatic B-cell population expressed S-100b-like immunoreactivity.     

Immunocytochemical detection of glucagon and insulin cells in endocrine pancreas and cyclic disparity of plasma glucose in the turtle Melanochelys trijuga

The present investigation was carried out to know the seasonal variation in plasma glucose,insulin and glucagon cells during the reproductive cycle of untreated Melanochelys trijuga. Pancreatic endocrine cells were immunochemically localized.Insulin-immunoreactive (IR) cells occurred in groups of 3-20 and were in close apposition, while glucagon-IR cells were distributed individually between the exocrine pancreas or formed anastomosing cords where cells were not intimately attached. Whenever both IR cell types were present together forming an islet,insulin-IR cells formed clusters in the centre with glucagon-IR cells being scattered at the periphery. Glucagon-IR cells seemed to be secretory throughout the pancreas during the reproductive cycle,while insulin-IR cells were found to be pulsating in their secretion. Mean size of the islet was 1.306, 0.184 and 2.558 mm in the regenerative, reproductive and regressive periods,respectively. In general,insulin-IR cells measured 5.18 (mu)m and glucagon-IR cells 5.22 (mu)m in their longest axis. Invariably, glucagon-IR cells were more in number than insulin-IR cells. The fasting plasma glucose level was 69.97 mg% during the regenerative period, which increased to 97.96 mg% during the reproductive period,and reached a peak value of 113.52 mg% in the regressive period.     

The endocrine pancreas of a squamate reptile, the desert lizard (Chalcides ocellatus). A histological and immunocytochemical investigation

The endocrine pancreas of the desert lizard (Chalcides ocellatus) was investigated histologically and immunocytochemically. The endocrine tissue was concentrated in the dorsal lobe, where it constituted about 7% of the total volume. In the ventral lobe the endocrine tissue formed approximately 1% of the total volume. Four endocrine cell types were observed in the pancreas of this species, namely insulin-, glucagon-, somatostatin- and pancreatic polypeptide (PP)-immunoreactive cells. The volume occupied by these cells was 1, 1, 0.6 and 0.3% of the total volume of the pancreas, respectively. Insulin-immunoreactive cells were located in the islet centre and comprised 3% of dorsal and 0.2% of the ventral lobe volume. Glucagon cells occurred at the islet periphery and amounted to 3 and 0.2% of the volume of the dorsal and ventral lobes, respectively. Somatostatin-immunoreactive cells were located at the islet periphery as well as in between the exocrine parenchyma. They constituted 1 and 0.2% of the volume of the dorsal and ventral lobes, respectively. PP-immunoreactive cells occurred mainly among the exocrine parenchyma as solitary cells. They formed only 0.03% of the volume of the dorsal lobe. The corresponding figure in the ventral lobe was 0.6%.     

Canine pancreatic polypeptide complementary deoxyribonucleic acid sequence: pancreatic polypeptide and insulin messenger ribonucleic acid distribution in the lobes of the pancreas

The structure of the canine prepropancreatic polypeptide (preproPP) cDNA was determined. The nucleotide sequence conservation between human and canine preproPP is very high for the signal peptide (82%) and the region coding for the 36 amino acid pancreatic polypeptide (PP) (92%). The overall sequence homology for the C-terminal portion of proPP containing the icosapeptide and a C-terminal extension peptide is only 63% whereas the 3'-untranslated regions of human and canine PP mRNA share 73% homology after alignment for maximal homology. The only sequence conservation in icosapeptide is the region coding for the last 10 amino acids of the icosapeptide. Comparison of PP immunoactivity and PP mRNA concentrations in extracts of the developmentally distinct uncinate process and splenic lobes of the canine pancreas revealed the same ratio of mRNA concentrations (16 +/- 6.5) and PP peptide concentrations (18 +/- 7.0) in the uncinate process compared to the splenic lobe (n = 6). However, a similar comparison of insulin C-peptide (CP) immunoactivity and insulin mRNA concentration revealed a smaller ratio of CP immunoactivity (0.37 +/- 0.05) than insulin mRNA (0.58 +/- 0.10) between the same lobes (P less than 0.0074, n = 6). This increased steady state CP concentration relative to insulin mRNA in splenic lobe compared to the uncinate process was not observed for PP peptide and mRNA.     

Impaired differentiation of endocrine and exocrine cells of the pancreas in transgenic mouse expressing the truncated type II activin receptor

Activin A is expressed in endocrine precursor cells of the fetal pancreatic anlage. To determine the physiological significance of activins in the pancreas, a transgenic mouse line expressing the truncated type II activin receptor under the control of beta-actin promoter was developed. Histological analyses of the pancreas revealed that the pancreatic islets of the transgenic mouse were small in size and were located mainly along the pancreatic ducts. Immunoreactive insulin was detected in islets, some acinar cells, and in some epithelial cells in the duct. In addition, there were abnormal endocrine cells outside the islets. The shape and the size of the endocrine cells varied and some of them were larger than islets. These cells expressed immunoreactive insulin and glucagon. In the exocrine portion, there were morphologically abnormal exocrine cells, which did not form a typical acinar structure. The cells lacked spatial polarity characteristics of acinar cells but expressed immunoreactive amylase, which was distributed diffusely in the cytoplasm. Plasma glucose concentration was normal in the transgenic mouse before and after the administration of glucose. The insulin content of the pancreas in transgenic and normal mice was nearly identical. These results suggest that activins or related ligands regulate the differentiation of the pancreatic endocrine and exocrine cells.     

The endocrine pancreas of a squamate reptile,the desert lizard (Chalcides ocellatus)

Summary The endocrine pancreas of the desert lizard (Chalcides ocellatus) was investigated histologically and immunocytochemically. The endocrine tissue was concentrated in the dorsal lobe, where it constituted about 7% of the total volume. In the ventral lobe the endocrine tissue formed approximately 1% of the total volume. Four endocrine cell types were observed in the pancreas of this species, namely insulin-, glucagon-, somatostain- and pancreatic polypeptide (PP)-immunoreactive cells. The volume occupied by these cells was 1, 1, 0.6 and 0.3% of the total volume of the pancreas, respectively. Insulin-immunoreactive cells were located in the islet centre and comprised 3% of dorsal and 0.2% of the ventral lobe volume. Glucagon cells occurred at the islet periphery and amounted to 3 and 0.2% of the volume of the dorsal and ventral lobes, respectively. Somatostatin-immunoreactive cells were located at the islet periphery as well as in between the exocrine parenchyma. They constituted 1 and 0.2% of the volume of the dorsal and ventral lobes, respectively. PP-immunoreactive cells occurred mainly among the exocrine parenchyma as solitary cells. They formed only 0.03% of the volume of the dorsal lobe. The corresponding figure in the ventral lobe was 0.6%.     

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.     

Ontogeny of some endocrine cells of the digestive tract in sea bass (Dicentrarchus labrax): An immunocytochemical study

Serotonin- and ten peptide-immunoreactive (IR) cell types were identified in the digestive tract of sea bass (Dicentrarchus labrax L.) larvae of four morphofunctional phases ranging in age from hatching to 61 days. The sequence of appearance and location of endocrine cells during ontogenetic development of the larvae was determined. The differentiation of endocrine cells followed a distal-proximal gradient in the gut which paralleled the morphofunctional differentiation. Serotonin-IR cells were identified in the last portion of the digestive tract from phase I onwards and in the gastric region from phase III, before these regions were morphofunctionally differentiated; met-enkephalin-IR cells were identified from phase II onwards in both the differentiated rectum and the undifferentiated intestine; cholecystokinin (CCK)- and synthetic human gastrin-34-IR cells were located only in the intestine and first found in the undifferentiated intestine of phase II; human gastrin-17-, peptide YY (PYY)- and neuropeptide Y (NPY)-IR cells appeared in the intestine from phase II and in stomach in phase IV, when it showed gastric glands; pancreatic polypeptide (PP)- and glucagon-IR cells were observed in both intestine and stomach, but insulin- and somatostatin-IR cells only in stomach, from phase III, during which the intestine but not the stomach was differentiated. PP- and PYY-, PP- and glucagon-, and PYY- and glucagon-like immunoreactivities coexisted from their first appearance in some cells of the gut.