Basal-granulated Cells Research Articles

Ultrastructural Identification of the Basal-Granulated Cells in the Duodenum of Albino Rat

The fine structure of the crypt epithelium of the duodenal mucosa in albino rats was studied to represent the types and distribution of the basal-granulated or endocrine cells. Twenty male animals were used. Perfusion-fixation was made and samples of duodenal mucosa were taken and processed to prepare epon-embedded specimens for examination by a transmission electron microscope. Cells containing membrane-bound granules were seen in the crypt epithelium. They were identified to be basal-granulated cells. Six different types of such cells were demonstrated. All of the cells were of the closed type. The possible functional significance of these closed cell types was discussed. Correlation among the distributions of such cells in the intestine of albino rat might enable the physiologists, internists and other research workers to study several biologically active peptides with well-established functions other than those which have long been investigated.

Cyclooxygenase (COX)-1 and COX-2 Both Play an Important Role in the Protection of the Duodenal Mucosa in Cats

Although nonsteroidal anti-inflammatory drugs often cause ulcers in the duodenum in humans, the role of cyclooxygenase (COX) isoforms in the pathogenesis of duodenal ulcers has not been fully elucidated. We examined in cats the 1) ulcerogenic effects of selective COX-1 (SC-560, ketorolac) and COX-2 (celecoxib, meloxicam) inhibitors on the gastrointestinal mucosa, 2) effect of feeding and cimetidine on the expression of COX isoforms and prostaglandin E(2) (PGE(2)) level in the duodenum, and 3) localization of COX isoforms in the duodenum. COX inhibitors were administered after the morning meal in cats once daily for 3 days. Gastrointestinal lesions were examined on day 4. Localization and expression of COX isoforms (by immunohistochemistry, Western blot) and PGE(2) level (by enzyme immunoassay) were examined. Results were as follows. First, selective COX-1 or COX-2 inhibitors alone produced marked ulcers in the duodenum but did not cause obvious lesions in the small intestine. Coadministration of SC-560 and celecoxib produced marked lesions in the small intestine. Second, feeding increased both the expression of COX isoforms and PGE(2) level in the duodenum, and the effects were markedly inhibited by pretreatment with cimetidine. Third, COX-1 was localized in goblet and Brunner's gland cells, Meissner's and Auerbach's plexus, smooth muscle cells, and arterioles; and COX-2 was observed in capillaries, venules, and basal granulated cells. The expression of COX isoforms in the duodenum is up-regulated by feeding, and inhibition of either COX-1 or COX-2 causes ulcers in the duodenum, suggesting that both isoforms play an important role in the protection of the duodenal mucosa.

Fine structure of the anal tonsilliar epithelium in the laboratory shrew (Suncus murinus).

The epithelium of the anal tonsil of the laboratory shrew was studied by scanning and transmission electron microscopy, with particular attention focused on the structure of the epithelium lining the anal tonsillar crypt. The tonsillar crypt surface is lined by two kinds of epithelia: squamous epithelium, which is located mainly at the neck of the crypt and includes keratohyalin granules in the superficial layer, and reticular epithelium, which is invaded by many immigrating cells and has several micropores immigrating cells to pass through. In addition, basal granulated cells are present in the basal layer. These results suggest that the reticular epithelium of the anal tonsil belongs to the well-developed gut-associated lymphoid tissue (GALT) in the alimentary canal. It represents a specialized and important compartment in immunological function, similarly to the palatine tonsils of other mammals, and has as yet unknown roles in digestion.

Immunocytochemical localization of prohormone convertases PC1 and PC2 in the mouse thyroid gland and respiratory tract.

We examined immunocytochemical localization of the prohormone convertases, PC1 and PC2, in the thyroid gland and respiratory tract of the adult mouse using the indirect enzyme- and immunogold-labeled antibody methods for light and electron microscopy, respectively. In the thyroid gland, PC1- and/or PC2-immunoreactive cells were cuboidal, scattered in the follicular epithelium and in the interfollicular spaces. When serial sections were immunostained with anti-calcitonin, anti-PC1, anti-calcitonin-gene-related-peptide (CGRP), and anti-PC2 sera, respectively, localization of both PC1 and PC2 was restricted to the calcitonin/CGRP-producing parafollicular cells. In the respiratory tract, only PC1 immunoreactivity was observed in the basal granulated neuroendocrine cells, which were scattered in the tracheal epithelium. Consecutive sections immunostained with anti-PC1 and anti-CGRP sera showed that a subpopulation of these PC1-immunoreactive cells contained CGRP. Double immunogold electron microscopy of the thyroid parafollicular cells revealed that calcitonin- and/or CGRP-immunopositive secretory granules were also labeled with both PC1 and PC2. These findings suggest that procalcitonin is proteolytically cleaved by PC2 alone or by PC2 together with PC1, and that the proCGRP is cleaved by PC1.

Selenium-Dependent Glutathione Peroxidase-GI Is Localized in Basal Granulated Cells of Rat Stomach

Selenium-Dependent Glutathione Peroxidase-GI Is Localized in Basal Granulated Cells of Rat Stomach

Light microscopic autoradiographic study of DNA synthesis in cecal epithelial cells of aging mice.

The localization and activity of DNA synthesis of mouse cecal epithelia from prenatal Day 19 embryos to 12-month adults were investigated by light microscopic autoradiography after [3H]-thymidine injection in vivo. The cecal epithelial labeled cells with [3H]-thymidine were located at the lower half of the crypts, and the labeling index (LI) changed with the development of the cecum due to aging. A peak in the LI of absorptive cells was found at embryonic Day 19, but it decreased strikingly at the first postnatal day and then kept an almost constant value until 12 months. The LI of the goblet cells showed the highest value at fetal Day 19, decreased gradually with aging from the first postnatal day, and completely disappeared from 1 month onwards. The basal granulated cells were located only in the base of crypts, and the significant difference of LI was not found from embryonic Day 19 through 12-month adult. The results obtained in this study suggest that there are some differences of DNA synthesis among different kinds of cecal epithelial cells from embryonic stages to postnatal stages as a result of aging.

Protein kinase C ?-, ?- and y-subspecies in basal granulated cells of rat duodenal mucosa

Protein kinase C [cPKC: alpha, beta (beta I, beta II), gamma], a Ca(2+)- and phospholipid-dependent enzyme, has been thought to play a critical role in the synthesis and secretion of gut hormones in gastrointestinal mucosa. However, the localization of PKC has not yet been clarified at the cellular level in the gastrointestinal epithelium. The present study was made to identify cPKC-containing cells immunohistochemically in the rat duodenal epithelium by light and electron microscopy and by confocal laser scanning microscopy. Special attention was paid to the demonstration of cPKC in basal granulated cells. By light microscopy, some duodenal epithelial cells were demonstrated to be immunopositive for PKC alpha-, beta- and gamma-subspecies. Their distribution and incidence were almost similar to those of cells stained by the silver impregnation method of Grimelius. By electron microscopy, profiles of secretory granules were found at the basal region of the PKC-immunopositive epithelial cells. When the cells were double-immunostained for gastrin, serotonin or somatostatin and for PKC alpha-, beta- or gamma-subspecies, these gut hormones and PKC subspecies were shown to colocalize as examined by confocal laser scanning microscopy. These findings show that cPKC (alpha, beta, gamma) is present in basal granulated cells such as G-, EC- and D-cells, presumably playing some important role in regulation of gut hormones, including their synthesis and/or secretion.

Cluster Formation of Basal-Granulated Cells in the Intestinal Villi of the Fetal Japanese Monkey (<i>Macaca fuscata fuscata</i>)

Segi's cap, an aggregation of the basal-granulated cells in the intestinal villi of the fetal Japanese monkey was investigated by means of light microscopy and immunocytochemical techniques. Characteristic Segi's caps were observed at the tips of the villi in the duodenum and upper jejunum in fetal Japanese monkeys, aged 120 and 140 days. The Segi's cap of Japanese monkeys is characterized by the following morphological features: 1) There are relatively fewer caps per section in comparison with humans. 2) The number of basal-granulated cells of the cap is also less than in humans. 3) The characteristic indentation at the center of the Segi's cap, reported in humans, cattle and pigs is only rarely present. 4) Argentaffin cells, which are now known as serotonin-containing cells, are present in the monkey Segi's cap. 5) Somatostatin-, motilin-and CCK-immunoreactive cells are found in the monkey Segi's cap.

Segi's cap: group formation of gut endocrine cells at the tip of the villi in human embryonal intestine.

Large groups of basal-granulated (entero-endocrine) cells occur on the top of villi in the duodenum and upper jejunum of the human fetus older than five months of gestation. This structure was discovered and described by Segi(1935), hence named Segi's cap. By the immunocytochemical technique, somatostatin-, gastrin- and motilin-producing cells were demonstrated. By electron microscopy, EC, D and S cells were identified in the cap. There were autonomic nerves in the lamina propria adjacent to Segi's cap. No intraepithelial lymphocytes were found in the villi with Segi's cap.

Demonstration of dopamine-immunoreactive cells in the gastrointestinal tract of gerbils (Meriones unguiculatus).

We investigated dopamine immunoreactivity in the small intestine of gerbils (Meriones unguiculatus), using a sensitive and selective antibody against glutaraldehyde-conjugated dopamine. Dopamine-immunoreactive cells were found within the mucosal epithelium along the entire extent of the small intestine. Labeled cells were regularly distributed in the upper half of the intestinal villi, basally attached to the basement membrane and always reaching as far as the epithelial surface. Dopamine-containing cells revealed a spindle-like shape, and both light and electron microscopic characteristics relate them to typical open-type gut endocrine cells. Thus, this current study directly identified dopamine as a probable secretory product in basal granulated cells of the small intestine. The functional significance of these cells is discussed in relation to the current view of dopaminergic actions in peripheral tissues.

Heterotopic Gastric Mucosa of the Small Intestine in Laboratory Beagle Dogs

Out of the 365 young laboratory beagle dogs which were used in 17 toxicity bioassays, 15 cases (4.1%) were diagnosed as having congenital heterotopic gastric mucosa of the small intestine. Its incidence in the male dogs (12 cases out of 187) was higher than in the female dogs (3 cases out of 178). Grossly, the lesions were seen as an ulcerous focus of the small intestine, 25 cm to 88 cm proximal to the ileocecal valve. All of the lesions were quite similar histologically and electron microscopically to the normal gastric mucosa, which are composed of the surface mucous cells, chief cells, parietal cells, mucous neck cells and basal granulated cells of the stomach. And consequently, they were considered to be that of a congenital heterotopic tissue in the small intestine. The only morphological characteristic of these lesions different from the regular gastric mucosa was an association with the tubular structure seen in the basal region of these mucosal layers. These cells were considered to be of mucous-secreting cell origin because of secreting type III mucous evident from paradoxical concanavalin A or periodic acid Schiff stains. They seemed to be protecting the surrounding intestinal mucosa from gastric acid.

Calcitonin gene-related peptide-like immunoreactive cells in the secretory portions of rat sweat glands

We found cells with calcitonin gene-related peptide-like immunoreactivity and with many cored vesicles in the secretory portions of sweat glands of rat foot pads. About 10% of sweat glands contained single immunoreactive cells. The immunoreactive cells were flask-shaped, with a narrow apex facing the glandular lumen and the bulk of the cell body in the basal half of the glandular wall. In the cytoplasm, there were many vesicles, 100-250 nm in diameter, with cores of various electron densities. These cytochemical and cytological characteristics suggest that the immunoreactive cells are homologous to gastrointestinal basal granulated cells.

Distribution of serotonin-immunoreactive paraneurons in the lower urinary tract of dogs.

Morphological and quantitative studies were made on serotonin-containing paraneurons throughout the lower urinary tract in male and female dogs. Using an anti-serotonin antiserum, the cells were consistently demonstrated to be dispersed in the epithelium from the vesico-urethral junction to the external urethral ostium. They occurred most frequently in the urethra proximal to the urogenital diaphragm in both sexes. The total number of the serotonin-immunoreactive cells in the urethra was estimated to be 36.2 X 10(4) (SD 9.9 X 10(4] in the male (n = 3) and 15.6 X 10(4) (SD 2.1 X 10(4] in the female (n = 3). Besides the urethra, the prostate and vaginal vestibule contained several serotonin-immunoreactive cells. The urethral serotonin cells were basically bipolar basal-granulated cells that extended the basal cytoplasm to the basement membrane and reached the lumen with an apical process. Modified cell shapes were, however, also frequent, and included bifurcated apical and/or basal processes or a laterally directed basal process. Occasional serotonin cells possessed a threadlike basal process with varicosities and a terminal bouton, reminiscent of a neuronal process. Immunoreactivity for chromogranin A, a carrier protein common to endocrine paraneurons, was demonstrated in all of the urethral serotonin cells. The chromogranin A-immunoreactive granules accumulated more densely in the basal and perinuclear regions of the cell. It is hypothesized that the serotonin-immunopositive paraneurons may receive chemical and/or physical information from urine and, in response to it, secrete serotonin which presumably causes the contraction of the musculature of the urethra.

Serotonin-immunoreactive cells of peculiar shape in the urethral epithelium of the human penis

The present study deals with endocrine-like cells in the urethra of human penis. A large number of basal-granulated cells immunoreactive for serotonin were dispersed in the urethral epithelium. No cellular elements were stained positively with antisera against bioactive peptides. The serotonin-immunoreactive cells consisted of a small oval perikaryon and slender processes, and resembled neurons in shape. An apical process reached the urethral lumen. The basal processes frequently branched out in a dendritic fashion, some running laterally for a considerable distance. The number of cells immunoreactive for serotonin was remarkably reduced in subjects over 60 years of age.

Evidence for the presence of a histaminergic neuron system in the rat brain: An immunohistochemical analysis

Histamine-containing cells in rats were identified by indirect immunofluorescent histochemistry using an antibody raised against histidine decarboxylase (HDC), the enzyme forming histamine, which was purified from fetal rat liver. HDC-like immunoreactive (HDCl) structures could be detected in the brain as well as in peritoneal mast cells and basal-granulated cells in deep crypts of the gastric mucosa of rats. Numerous HDCl neurons were found in the posterior hypothalamic area and HDCl nerve fibers with a varicose appearance of fluorescence were widely distributed in various regions of the brain.

Basal-granulated cells in human Brunner's glands.

Basal-granulated cells (BGC) in the human duodenal bulb were observed by light and electron microscopy, and both the cell types and their population densities in the duodenal crypts and in the Brunner's glands were compared. The number of the BGC in the Brunner's glands was much smaller than in the crypts. On the basis of their ultrastructural features, nine types of BGC, i.e. an EC cell, N cell, D cell, D1 cell, S cell, I cell, G cell, L cell and P cell were identified in the human duodenal bulb. In the duodenal crypts, as is generally recognized, EC cells were most numerous, making up 40% of the total BGC. N cells and D cells were around 10% of the total, and S cells, I cells and L cells were less than 10%, respectively. By contrast, in Brunner's glands, D cells and small granule-containing cells such as S cells, I cells and D1 cells were predominant, accounting for about 80% of the total BGC. EC cells and N cells were about 10% or less, respectively. These results indicate that the Brunner's glands are definitely different from the ordinary intestinal mucosa in regard to their BGC population, and are considered to have endocrine functions mainly performed by D1 cells, S cells and I cells.

Immunocytochemical identification of polypeptide YY (PYY) cells in the human gastrointestinal tract.

Various parts of the human gastrointestinal tract were investigated immunocytochemically for the occurrence of polypeptide YY (PYY) and pancreatic polypeptide (PP). PYY-immunoreactive cells were observed in the lower part of the ileum, in the colon and in the rectum, and PP-immunoreactive cells were found in the colon and rectum. Both cell types were of the open type, i.e. they extended from the basal lamina to the gut lumen. PYY-immunoreactive cells were seen to emit cytoplasmic processes to the neighbouring goblet cells. This latter observation suggests that PYY cells may exert a paracrine action on the mucus-secreting goblet cells. Staining of consecutive thin plastic sections and staining of the same section simultaneously for two peptides showed that PYY-immunoreactivity did not occur in PP- or enteroglucagon-immunoreactive cells. On the ultrastructural level PYY-immunoreactivity was localized in basal granulated endocrine cells. These cells contained round or slightly oval electron dense granules with a mean diameter of 150 nm (range 100-300 nm).

An immunohistochemical and ultrastructural study of Segi's cap, a large aggregation of gut endocrine cells, in bovine fetuses.

Segi's cap, a large aggregation of basal-granulated cells at the top of the intestinal villus, was studied in the proximal small intestine of bovine fetuses by histological, immunohistochemical and ultrastructural techniques. 1) Typical Segi's caps were seen in the duodenum and proximal jejunum in bovine fetuses. 2) Smaller groups of basal-granulated cells were found in the villous and partly also in the cryptal epithelium, as well as in the subepithelial lamina propria. The possible mechanism for their occurrence was discussed in connection with the fate of the cap. 3) Segi's caps were present in a neonatal calf before the suckling stage, but not in 3 or 4 week-old calves. The process of and reason for this abrupt disappearance of the caps are unknown. 4) The Segi's cap in bovine fetuses consisted mainly of argyrophil cells as demonstrated by Grimelius' and Hellerström-Hellman's silver methods. Only a few argentaffin cells were found in fetal caps using a modified Masson-Hamperl's silver method. 5) Immunohistochemically, somatostatin-, gastrin-, motilin- and secretin-immunoreactive cells were identified. 6) Four different endocrine cell types could be distinguished in the bovine Segi's cap on the basis of the ultrastructural appearance of their secretory granules.

Tubulo-vesicular structures in the basal cytoplasm of gut basal-granulated cells revealed by zinc iodide-osmium tetroxide staining.

Zinc iodide-osmium tetroxide staining was applied to the duodenum of a human fetus for the purpose of investigating the fine structure of basal-granulated cells. A positive reaction was demonstrated within a peculiar network consisting of fine tubulo-vesicular structures in the basal cytoplasm. The possibility was discussed that these structures represent a device by which the granule membrane returns to the Golgi complex after the exocytotic release of gut hormones.

Fine Structure of the Musculature of the Silkworm Larval Midgut

The musculature of the larval midgut of the silkworm, Bombyx mori, is composed of outer set of longitudinal muscle fibers and inner set of circular muscle fibers. The circular muscle fibers are closely approximated and their plasma membranes are occasionally seen to be in close apposition. The muscle fibers are elongate uninucleate cells with a single myofibril in their sarcoplasm. The sarcomeres are divisible into A-, I-, H- and Z-bands. In the A-band region 12 thin myofilaments surround each thick myofilament. In fully contracted muscle fibers, the Z-band material is completely broken up into separate masses with spaces between them and there is an interdigitation of thick myofilaments from adjacent sarcomeres across these spaces. the sarcoplasmic reticulum frequently constitutes surface dyads with the plasma membrane but rarely associates with the transverse tubular system in the dyad configuration. The tracheal tissue appears to be the only cellular element that occurs in the interior of the musculature. Basal-granulated cells occur in the midgut epithelial layer.