Biomedical subjects

S Aiyama

Publications and source records attributed to S Aiyama.

18 recordsLinked to original sources

PubMed2003

Histochemical and chronological analysis of mouse submandibular gland parenchyma subjected to abrupt reperfusion.

We examined the effects of abrupt reperfusion on the mouse submandibular gland parenchyma and determined the degree of recovery from tissue damage. A main trophic artery supplying the gland was ligated with silk thread, and the ligature was then released after a variable period. The gland was removed at various times after reperfusion and then examined immunohistochemically and ultrastructurally. With reperfusion after 15 or 30 min of ligation, the tissue damage to the glands was slight or inapparent. With reperfusion after 1 or 3 h of ligation, collapse of the acini and the ducts was observed in parts of the lobules, but restoration of the parenchymal structures occurred, with the appearance of PCNA-positive cells, although there were differences in the level of restoration. After 6 h of ligation, most of the normal parenchymal cells had disappeared by the 5th and 7th days after reperfusion, and apoptosis and necrosis were present. These findings suggest that if interruption of the blood supply to the submandibular gland parenchyma is limited to within a few hours, then tissue repair after reperfusion is possible, although this will differ according to the level of damage, because the acini and the ducts reappear, probably with proliferation of parenchymal cells.

Alcian Blue↗

PubMed2001

Morphological and histochemical changes in the secretory granules of mucous cells in the early postnatal mouse parotid gland.

It has previously been known that the developing parotid glands in humans and rats contain mucous cells in their terminal clusters and acini, but these cells disappear within a short period of time. Using rat parotid glands, IKEDA and AIYAMA (1997, 1999) suggested that the mucous cells might change into serous cells in the early postnatal period, but it is uncertain whether mucous cells appear only in the developing parotid gland of a few species such as humans and rats, or whether the cell transformation actually occurs. To clarify these points, the present study investigated the developing mouse parotid glands. Light microscopy showed cells with secretory granules that stained extensively with PAS and alcian blue in the terminal clusters of a 1-day-old mouse parotid gland. Mucous cell numbers in the terminal clusters and the acini reached a peak on day 5 and decreased on day 7. By day 10, the mucous cells had disappeared altogether. Thus, the presence of mucous cells in the developing mouse parotid gland was confirmed. Electron microscopy showed granules of low-electron-density and bipartite granules in the mucous cells. Bipartite granules and highly electron-dense granules sometimes co-existed in a single cell. Immuno-electron microscopy revealed a positive reaction for amylase to the low-electron-density granules and the low-electron-density portions of the bipartite granules, in addition to the highly electron-dense granules and the electrondense cores of the bipartite granules. No mucous cells with nuclei displaying characteristics of apoptosis were recognizable. Lectin histochemistry both at the light and electron microscopic levels showed that the secretory granules in the mouse parotid gland mucous cells had sugar residues similar to those of the mature serous granules. These findings demonstrate that mucous cells appear in the early postnatal mouse parotid gland, and that almost all of these cells may be converted into serous cells.

Amylases↗

PubMed2001

Developmental changes in the fine structure and histochemical properties of mucous cells in the parotid gland of the infant Japanese macaque.

Mucous cells have been known to occur in the terminal portions of the parotid gland in a few species of mammals during a limited period of their development. The aim of this study was to examine the occurrence and features of mucous cells in the parotid gland of the infant Japanese macaque. Light microscopy revealed that mucous cells in the macaque parotid gland were present in the terminal clusters and acini at postnatal day 15, were less prevalent at day 30, and continued to decrease in number over 3 months. Mucous cells were no longer recognized in the parotid gland in 6-month-old macaques. Electron microscopy showed that the mucous cells contained electron-lucent secretory granules and bipartite or tripartite secretory granules. By 3 months of age, there was a scarcity of mucous cells and a concomitant increase in transitional cells. These transitional cells were intermediate in structure between mucous and serous cells, and contained three types of granules: electron-lucent, bipartite or tripartite, and electron-dense. None of the cells showed apoptotic figures. Lectin histochemistry indicated that the mucous cells in the early postnatal period had sugar residues identical in nature to those seen in the granules from mature serous cells in the glands of 3-month-old macaques. Immunohistochemistry using an antibody against human alpha-amylase showed a weakly positive reactivity in the secretory granules of the mucous cells, starting from day 15. In the transitional cells, the electron-dense granules showed a stronger immunoreactivity than either the electron-lucent granules or the heterogeneously structured granules. These results suggest that the secretory granules of mucous cells have characteristics in common with those of serous cells, and that during the transitional period the mucous granules change from the initial electron-lucent to hetorogenous forms, finally becoming the electron-dense granules. The mucous cells in the parotid gland of the juvenile Japanese macaque are therefore suggested to be converted into serous cells.

Animals↗

PubMed2000

Fine structure of transforming-type granules in mucous cells in the early postnatal rat parotid gland when processed by rapid freezing followed by freeze-substitution fixation.

The present study was designed to clarify the more precise ultrastructural feature of granules, especially mucous granules in the early postnatal rat parotid gland by using rapid freezing followed by freeze-substitution fixation. The parotid gland of Wistar rats (aged 0-10 days) was removed under anesthesia and immediately underwent cryofixation followed by substitution with osmium tetroxide. After fixation, the samples were embedded in Epon-Araldite, cut into ultrathin section, and then examined by transmission electron microscopy. Electron microscopy showed that the mucous granules of samples treated by freeze-substitution fixation had low electron density and were almost spherical in shape with a clear limiting membrane. By Day 5, granules that were a little more electron dense than mucous granules, granules with a more electron dense portion at their periphery, and heterogeneous granules with an internal highly electron dense portion were found. Moreover, cells containing both homogeneous granules with a high electron density similar to that of mature serous granules and heterogeneous granules were observed. These findings demonstrated that the morphology of the transforming-type mucous granules by chemical fixation in the previous study was an artifact and, as a result, strongly suggested that on the sequential morphological changes of transitional mucous/serous granules by rapid freezing method in the present study, the mucous cells in the early postnatal rat parotid gland undergo transformation to serous cells.

Animals↗

PubMed2000

Uptake of cationized ferritin by the epithelium of the main excretory duct of the rat submandibular gland.

Previous studies demonstrated that the main excretory duct (MED) of the rat submandibular gland can internalize exogenous protein in addition to reabsorbing and secreting electrolytes. However, more precise studies have not been conducted. The aim of this study was to elucidate the cell types responsible for endocytosis of an exogenous protein (ferritin) and to follow the movements of the endocytosed protein in the ductal epithelial cells. The MEDs of the right submandibular gland of male Wistar rats were exposed near the glands proper and cationized ferritin solution was injected into each MED through a fine glass cannula. The MEDs were removed at intervals after ferritin injection, fixed and examined by transmission electron microscopy. The epithelium of the MED of the rat submandibular gland was pseudostratified and consisted of light (types I and II), dark, tuft and basal cells. Uptake of ferritin by the light (types I and II) and dark cells occurred frequently. Small vesicles and multivesicular bodies containing ferritin particles were observed in the supra-nuclear and lateral nuclear cytoplasm. Endocytosis of tracers by tuft cells was rare. Some of the small vesicles and the multivesicular bodies were acid phosphatase-positive. By 60 min after treatment, ferritin-containing small vesicles and multivesicular bodies appeared in the basal cytoplasm. Ferritin particles were also observed in basal extracellular spaces. The light (types I and II), dark and tuft cells (latter rarely) participated in endocytosis of exogenous proteins in the epithelium of the MED of the rat submandibular gland. Almost all of the internalized proteins appeared to be processed by the lysosomal system, and some proteins were released into the extracellular spaces.

Acid Phosphatase↗

PubMed1999

Developmental changes of sugar residues and secretory protein in mucous cells of the early postnatal rat parotid gland.

Mucous cells have been identified in the terminal portions of the early postnatal parotid gland in human and rat, although mature parotid gland acini are composed of serous cells or seromucous cells. Previously, Ikeda et al. demonstrated that mucous cells are present in the rat parotid gland on days 1 to 8 after birth and that the secretory granules within these mucous cells share some histochemical characteristics with mature serous cells. However, it is still not clear whether the mucous cells change into serous cells as the gland develops. The purpose of this study was to determine whether the mucous cells that appear in the early postnatal rat parotid gland change into serous cells. Parotid glands were obtained from male or female Wistar rats (aged 0-14 days and adults). Fixed tissue sections were reacted with soybean agglutinin (SBA) and wheat germ agglutinin (WGA) to detect glycoconjugates, or were stained using an anti-neonatal submandibular gland protein B1 (SMG-B1) antibody to identify serous acinar cells. The sections were observed by transmission electron microscopy. Electron microscopy revealed that cells with characteristics intermediate between those of mucous and serous cells (transitional cells) appeared around day 8 and that the nuclei of these cells did not show chromatin condensation, a characteristic of apoptotic cells. Lectin histochemistry showed that the mucous cells had the same sugar residues as the serous cells, which appeared after day 10. Immunohistochemistry with an anti-SMG-B1 antibody gave a positive reaction not only in the cells with highly electron-dense granules but also in the electron-dense cores of bipartite or tripartite granules in the transitional cells. Cells with morphological characteristics intermediate between those of mucous and serous cells (transitional cells) appearing in the early postnatal rat parotid gland begin to produce B1-immunoreactive protein common to serous acinar cells during development of the gland.

Animals↗

PubMed1997

Developmental changes in mucous cells of the early postnatal rat parotid gland: an ultrastructural and histochemical study.

Previous studies on the development of the parotid gland in various mammals have demonstrated that terminal clusters and acini contain mucous cells during the early postnatal period. However, little information has been available concerning the exact fate of the secretory granules in the mucous cells, specifically as to whether or not the mucous cells differentiate into serous cells. The present study aimed to determine the time of appearance of the mucous cells in the rat parotid gland as well as the morphological and histochemical changes of their granules. Light microscopy showed that cells positively stained with periodic-acid Schiff and alcian blue were sparsely distributed in the terminal clusters and acini on day 1 but had multiplied to a maximal level by day 5. They decreased in number on day 8 and were not recognizable at all by day 10. Electron microscopy revealed that the mucous cells initially contained granules of homogeneous low electron density, and then bipartite and tripartite granules with electron-dense cores were detected. By day 8 granules showing bipartite and tripartite structures and granules of homogeneous high electron density were seen to coexist in single cells. These observations suggest that mucous cells exist in parotid glands for a limited period of time and that, as the gland develops, the mucous granules come to resemble serous granules. Lectin histochemistry indicated that the secretory granules in the mucous cells were positive for peanut agglutinin, soybean agglutinin and wheat germ agglutinin, suggesting the occurrence of beta -D-galactose, alpha -D-N-acetyl galactosamine and beta -D-N-acetyl glucosamine which are the same sugar residues as those found in the granules of mature parotid serous cells. Immunostaining showed that even the low electron-dense granules in the mucous cells were weakly reactive for anti-rat parotid gland amylase; this reactivity gradually increased with development. These results suggest that mucous cell secretory granules which contain abundant glycoconjugate for a limited period during the development of the gland may change into serous granules.

Aging↗

PubMed1995

Ultrastructural changes of secretory cells of salamander lingual salivary glands under varying conditions.

BACKGROUND: In general the ultrastructure of secretory cells can be modified under secretory stimulated and non-stimulated conditions. The ultrastructure of the lingual salivary glands of hibernating salamanders in the natural environment was examined and compared to those of fasted and fed animals kept in the laboratory. METHODS: Hibernating salamanders of the species Hynobius tokyoensis were collected from the natural environment during the winter breeding season and sacrificed for this study. One group was sacrificed immediately, another group was kept under fasted condition, and another group was regularly fed; both of the latter groups were kept at room temperature for 1 month and then sacrificed. The tongue was fixed for electron microscopy and processed by conventional method, and semithin sections were histochemically examined for glycoconjugates. RESULTS: The lingual salivary glands of this salamander species were composed of simple or often branched tubular glands opening onto the dorsal surface of the tongue. The secretory cells which composed their terminal portions were all columnar in morphology and histochemically mucous in nature. Under hibernation or prolonged fasting at room temperature, the mucous granules of these columnar secretory cells were decreased in number and the Golgi apparatus appeared inactive. A conspicuous structural peculiarity was multiple fingerprint-like structures of the rough-surfaced endoplasmic reticulum (RER). Most of these membranes were composed of stacks of tightly packed cisternae. Under regular feeding, the mucous granules were closely packed in the cytoplasm of the secretory cells and the basal nucleus was slightly enlarged. The Golgi apparatus showed progressive activation with distended saccules. The unique membranous arrangement of the RER which was observed in the fasting animals was completely absent, and the cisternae were irregular in width with considerable variation of the intercisternal spaces. CONCLUSIONS: The tongue of the salamander H. tokyoensis has numerous tubular salivary glands which are mucous in nature. The architecture of the organelles in the secretory cells is subject to modification in response to the cellular metabolism.

Animals↗

PubMed1989

[Histochemical properties of secretory granules and fine structure of terminal portion in the Japanese Macaque labial gland].

The terminal portion of the Japanese macaque (Macaca fuscata) labial gland was examined ultrastructurally and histochemically. The results obtained are as follows. 1) The Japanese macaque, Macaca fuscata has the upper and the lower labial glands, which can be described as a compound tubulo-acinar gland. 2) The terminal portion of the labial gland appears to be consisted of the mucous acini and the demilunes when examined with the light microscope. 3) The secretory granules containing in the glandular cells of the mucous acini and the demilunes are negative with napthol yellow S, ninhydrin-Schiff and DMAB nitrite. 4) The secretory granules containing in the glandular cells of mucous acini stain intensely with PAS, alcian blue (pH1.0, 2.5, 3.5), colloidal iron and PA-methenamine silver, while those of demilunes are negative with alcian blue (pH1.0). The glandular cells of demilune with the PA-methenamine silver method shows weak positive granules and positive granules which are limited to the hallo of them. 5) In the mucous acini the mucous granules are ejected from glandular cells by the process of exocytosis. 6) The myoepithelial cell can be seen in the terminal portion. This cell surrounds the acini with long processes. These findings suggest that the glandular cells of the demilune have the granules containing mucopoly saccharides and a small quantity of protein in addition to the mucous granules, although the terminal portion of the Japanese macaque labial gland is nearly composed of mucous cells.

Animals↗

PubMed1989