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1.
The secretory endpieces of the rabbit submandibular gland are unusual in that they consist of seromucous acini (not demilunes) that empty into serous tubules that in turn drain into intercalated ducts. Seromucous granules consist of a moderately dense spherule in a fibrillogranular matrix. Serous granules contain a feltwork of filaments, which are liberated as a tangled skein during exocytosis. Peculiar granulated cells that have secretory granules of complex morphology are present at each end of the serous tubules. Intercalated ducts are, cytologically speaking, relatively simple, but the duct cells may contain a few oblong secretory granules. Striated ducts are typical in structure, although postfixation with ferrocyanide-reduced osmium reveals significant amounts of glycogen in the basal processes. Modified mitochondria are present in striated duct cells, but their frequency varies from rabbit to rabbit. Such mitochondria contain either an array of parallel, rigid cristae linked by intermembranous bridges, or a bundle of helical filaments within an expanded crista. Interspersed with the striated duct cells, especially near the duct origin, are some highly vacuolated cells with sparse mitochondria. Excretory ducts consisting of stratified columnar (sometimes pseudostratified) epithelium often show bleb formation of the luminal surface of the tall cells.  相似文献   

2.
The sublingual gland of Praomys natalensis, an African rodent that is phenotypically and cytogenetically intermediate to mice and rats, is a mixed gland, consisting of mucous acini that are capped by serous demilunes, of intercalated ducts, and of some short striated ducts that quickly become excretory ducts. The mucous cells are typical in appearance, with lucent granules that contain an assortment of scattered vermiform or particulate densities. The serous cells display an array of secretory granules with a highly unusual substructure. Rather than a pattern based on the manner in which light and dark regions are disposed in their matrix, these granules contain packets--some furled, some flat--of membranes that exhibit a pronounced axial periodicity of approximately 5 nm. Intercalated ducts are simple in structure, with no obvious morphological specializations. Striated ducts resemble those in the salivary glands of less exotic rodents, but they and the excretory ducts often have clusters of cytoplasmic crystalloids consisting of linear densities that intersect at right angles and that have a periodicity in both directions of approximately 12 nm.  相似文献   

3.
The sublingual gland of the cat consists primarily of branched secretory tubules that open into an abbreviated duct system. The simple epithelium that composes the secretory tubules consists of an admixture of mucous and serous cells, with the former predominating. Some secretory tubules are capped by a serous demilune. Regardless of position, almost all serous cells have prominent basal folds and border on at least one intercellular canaliculus as well as on the tubule lumen. Serous cells possess an extensive array of irregular, distended cisternae of rough-surfaced endoplasmic reticulum that frequently contain dense intracisternal granules. Serous granules are relatively few in number and rarely show evidence of substructure. Mucous cells, which lack basal folds, contain an apical mass of secretory material in the form of partially fused droplets. The duct system is somewhat less ordered than in most major salivary glands; secretory tubules empty into structures resembling intercalated ducts or may be in direct continuity with ducts intermediate in morphology between intercalated and excretory ducts. The absence of striated ducts noted in this study may be correlated with the high sodium content of cat sublingual saliva. The main excretory duct of the sublingual gland closely resembles that of the cat submandibular gland in terms of morphology, but exhibits little of the transport functions reported in the latter duct.  相似文献   

4.
We studied the morphology and ultrastructure of the bat (Pipistrellus k.k. and Rhinolophus f.e.) deep posterior lingual glands (Ebner's glands) during hibernation, summer and after stimulation with pilocarpine. Ebner's glands are formed by serous tubulo-alveolar adenomeres and by an excretory system organized in intercalated ducts, long excretory ducts and a main excretory duct. The latter opens in the vallum which surrounds the circumvallate papillae and in the groove of the foliate papillae. The secretory cells, which lack basal folds, show abundant and dense granules (PAS+, Alcian blue -), microvilli (scarce during hibernation), a Golgi apparatus (well developed during summer and after stimulation with pilocarpine), a large nucleus and RER cisternae stacked at the basal pole. Centrioles, lipid droplets, heterogeneous bodies (in content and density, probably lipofuscin bodies), lysosomal multivesicular bodies and large, dense granules with a microcrystalline structure were also encountered. The lateral membranes of adjacent cells are joined by desmosomes; their interdigitations are neither numerous nor prominent during summer. Microfilaments, often gathered in small bundles, lie in the lateral, peripheral cytoplasm without any relation with desmosomes. In summer and particularly after stimulation with pilocarpine, the apical pole of the secretory cells is characterized by many long microvilli, pedunculated hyaloplasmic protrusions and secretory granules. During hibernation the lumen is filled with secretory material. Myoepithelial cells are arranged among secretory cells or between them and the basal lamina. The short intercalated ducts show similarities with the analogous ducts of the parotid gland. Striated ducts are absent. Excretory ducts are endowed with: a) an inner layer of cuboidal cells characterized by poorly developed cytoplasmic organelles, rare dense granules and a few small microvilli; b) an outer layer of basal cells lying on the basal lamina. Myoepithelial cells are absent. The main excretory duct is lined by a stratified epithelium with an inner layer of conical-pyramidal cells surrounded by two-three rows of basal cells. The conical-pyramidal cells show poorly developed organelles, an apical border with small short microvilli and a prominent terminal web.  相似文献   

5.
Parotid glands of adult pigs were studied by light and electron microscopy. The parenchyma consists of acini, intercalated ducts, striated ducts, and excretory ducts. Acini had little affinity for periodic acid-Schiff and were alcian blue-negative at pH 2.6 or 0.5. These results indicate a paucity of neutral mucins and an absence of sialo- and sulfomucins. Histologically, acinar cells had vacuoles which corresponded ultrastructurally to large electron-lucent secretory granules. The latter contained electron-dense bodies and lipid droplets. Acinar cells differed histochemically and ultrastructurally from typical serous cells and were classified as special serous. Intercalated duct cells near acini contained electron-dense secretory granules and numerous microfilaments. Cells in distal segments lacked secretory granules. Striated ducts were lined by two types of columnar epithelial cells, light cells and dark cells. Light cells were characterized by numerous infoldings of the basal plasma membrane, mitochondria between the infoldings, and electron-lucent vesicles in the apical cytoplasm. The mitochondria contained tubular cristae. Dark cells were characterized by an abundance of microfilaments and numerous infranuclear processes which extended to the basement membrane. Excretory ducts, in addition to light and dark cells, also contained basal cells and goblet cells. Mitochondria in the light cells had flattened rather than tubular cristae. The pig parotid is a unique salivary gland and the most atypical mammalian parotid gland studied thus far. Mitochondria with tubular cristae and vacuolated special serous cells with lipid in the secretory granules are hallmarks of the pig parotid.  相似文献   

6.
The parotid and submandibular glands of the mongoose are described. Essential differences between the 2 glands were recognized in the acini; however, the intra- and interlobular ducts are built up similarly. The parotid gland is acinar. Its secretory cells are filled with distinct types of granula, which show a considerable variation of size and structure of their secretory material. Organelles are found sparsely. The submandibular gland, however, is tubuloacinar. Its tubuli are capped with cells which belong to the demilunes of v. EBNER, but because of their pale granules they occupy an exceptional position. As the acinar cells of the parotid gland, they form intercellular canaliculi by their plasmalemmata. In the secretory cells of the tubules an intimate contact between the rER and the granules is observed. The intralobular duct surface is built up by an onelayered epithelial cell formation. The cytoplasm of the intercalated duct cells is rich in bundles of filaments, and these cells contain mitochondria with a particular dense matrix. Some microvilli cover the apical surface. In the cells of the striated ducts several populations of granules differing in size and electron density are found. The material of the dense granules shows a marginal plate-like condensation, sometimes it cristallizes. It is supposed that they were released by an apocrine extrusion mechanism. Terminal axons innervate the acini, the duct cells, and also the myoepithelial cells. The findings are compared with the well-known morphology of the salivary glands of the cat.  相似文献   

7.
A histological, ultrastructural and histochemical study of the mandibular gland of the Australian possum Trichosurus vulpecula revealed essentially similar features as those described earlier for the mandibular gland of the taxonomically relatively unrelated American opossum Didelphis. The secretory endpieces consist of a branched tubular part, composed of serous cells whose secretion granules contain neutral glycoproteins, and terminal acini, consisting of seromucous cells containing small amounts of sialomucins. Relatively short intercalated ducts lead to striated ducts of variable ultrastructural appearance. The striated ducts run in bundles in the center of each sublobule of the gland. The possible functional significance of the abundance and variability in ultrastructure of the striated ducts is discussed.  相似文献   

8.
A new, third type of secretory cell was found in the acini of the submandibular gland in rat. In paraffin sections stained with hematoxylin-eosin or reacted with periodic acid-Schiff, acini containing the third type of secretory cells were found as a mass of darkly stained secretory endpieces at the periphery of the lobule. In semi-thin sections stained with toluidine blue, these cells showed numerous dense secretory granules in their cytoplasm. Some acini consisted entirely of these cells, whereas other acini consisted of an admixture of such cells and typical seromucous cells. Acini containing the third type of secretory cell tended to form clusters. Electron microscopically, the cells had well-developed rough endoplasmic reticulum and Golgi apparatus. The secretory granules showed a wide range of variation in substructure, even within the same cell. Well-developed intercellular interdigitation and intercellular canaliculi also were observed between adjacent third type of secretory cells. Although little is known about the biological significance of these cells and the properties of their secretory granules, the present study shows that the rat submandibular gland possesses three types of secretory cells in their secretory endpieces. © 1993 Wiley-Liss, Inc.  相似文献   

9.
Sublingual and submandibular glands were prepared for light and electron microscopy, and for histochemical staining with periodic acid-Schiff (PAS), Alcian Blue (AB) or both (AB-PAS). Between 15 and 17 days post-conception, the sublingual gland undergoes active morphogenesis from a single, solid bud into a branched glandular tree. At 18 days the first overt signs of secretory differentiation appear in the formation of cells with three kinds of secretion granules; that is, electron-dense serous granules, empty-looking mucous granules with fine thread-like substructures, and granules which have the general appearance of mucous granules but also contain an internal, electron-dense core (“mixed” granules). During the period from 18 to 20 days, all three types of granulated cells increase in number, with mucous cells predominating, and they all border directly on the acinar lumina, in seemingly random combinations in different acini. This diversity is reflected in the histochemical staining, since most acini and cells are both PAS- and AB-positive, but a substantial minority stain only with PAS, indicating that they contain serous granules. By comparison, all secretory cells in the submandibular gland stain with PAS but not with AB after the initial appearance of secretory granules at 18 days. From 20 days to birth (at 22 days), the cells with mixed granules disappear, while the cells with serous granules become fewer in number and displaced to the peripheral outpocketings of the acini. As a result of these changes, the general organization in the newborn is similar to that in the adult, i.e., purely mucous acini with serous demilunes.  相似文献   

10.
Naked-backed bats of the genus Pteronotus (family Mormoopidae) occur in the Neotropics from Mexico through northern South America. These are relatively small-sized insectivorous species that frequently roost in caves. Eight specimens of naked-backed bats (Pteronotus parnellii) were live-trapped in Suriname and one in Cuba (P. quadridens). Their parotid glands were fixed in an aldehyde mixture designed for field work and postfixed in the laboratory with osmium tetroxide. Tissues were further prepared for electron microscopy by conventional means. The parotid glands of the two species of Pteronotus closely resemble each other except for the substructure of their serous secretory granules. Serous granules in P. parnellii are bizonal, with a moderately dense inner matrix and an outer, denser corona or crescent. The matrix is occupied by laminae, flakes, and filaments in random array. In contrast, serous granules in P. quadridens consist of a uniform matrix that contains dense, usually stacked toroids or tubules either in random array or packed in bundles. A parotid gland from one specimen of P. parnellii contained an endpiece that consisted of cells that contained giant (up to 9 pm in diameter) serous granules. Serous cells in both species contain aggregates of small, uniformly dense, rod-like, membrane-delimited organelles as well as occasional bundles of cytofilaments. The endpieces are separated from intercalated ducts by a ring of granulated cells that contain secretory granules that often have a bull's-eye configuration. Intercalated and striated ducts are typical in appearance, except that many of the cells in the latter contain small, dense secretory granules in their apical cytoplasm. The parotid glands in the two species of naked-baked bats differ slightly in terms of acinar secretory granule ultrastructure, but otherwise are fairly conservative. It is thought that the glands in these particular bats might represent the "basal" condition of the salivary glands of insectivorous bats and thus can serve as a reference point for making comparisons to the highly diversified (in terms of diet) phyllostomid bats.  相似文献   

11.
The anterior buccal gland of the rat is a mucous salivary gland which develops as a branch of the main (Stensen's) duct of the serous parotid gland, a few mm from its oral orifice. The purpose of the present study was to further characterize the mature gland by means of electron microscopy and the histochemical demonstration of myoepithelial cells. The tubuloacini were found to have intercellular extensions (canaliculi) of the lumina, prominent Golgi complexes, and mucous secretory granules with a biphasic substructure. Discharge was by exocytosis of individual granules. The tubuloacini joined directly to striated ducts; no intercalated ducts were seen. First-order excretory ducts had larger lumina and shorter columnar cells, with fewer mitochondria and basal infoldings, than the striated ducts. Myoepithelial cells invested the tubuloacini but not the ducts. The anterior buccal gland has several features that are unusual for a minor salivary gland of mucous type, and which are usually associated with serous glands such as the parotid. It should provide a particularly interesting model for investigating factors which control the differentiation of secretory and myoepithelial cells, and the glycosylation of polypeptides to form mucous secretory products.  相似文献   

12.
Submandibular gland biopsies from four calves were examined by electron microscopy. Most of the parenchyma consists of mucous acini capped by seromucous demilunes. Secretory product of the demilunes reaches the acinar lumen via intercellular canaliculi located between adjacent demilunar cells or by narrow apical extensions of demilunar cells bordering the lumen in common with acinar cells. Intercellular canaliculi are absent between mucous acinar cells, but intercellular space is present at junctions of demilunar cells, acinar cells, and intercalated duct cells. Intercalated ducts are short and connect mucous acini with striated ducts. Striated ducts show more basal infoldings and mitochondria than those of bovine parotid glands. Nuclear bodies are present in most epithelial cell types of the gland but are larger and more easily recognized in nuclei of striated duct cells. Attempts are made to correlate the structure of bovine submandibular glands with its secretion of small amounts of hypotonic saliva relative to the larger volume of isotonic saliva secreted by parotid glands of the same animal.  相似文献   

13.
The aim of this study has been to determine the ultrastructural characteristics of the minor palatine salivary glands on the seventh day of development and to demonstrate wether their secretion is mucous, serous or seromucous by light, transmission and scanning electron microscopy. This study has shown that the palatine gland acinar cells are predominantly mucous with some serous units. These cells contain electron dense (serous) and low electron dense (mucous) granules in the apical portions. The cytoplasmatic organelles like mitochondria, Golgi apparatus and rough endoplasmic reticulum are localized in a supranuclear portion. We could also observe the flattened myoepithelial cells surrounding the basal part of the acini with myofilaments, Golgi apparatus and mitochondria. Desmosomal junctions and membrane interdigitations are present between the acinar and the myoepithelial cells. A basal lamina, divided in two layers, an electron dense and an electron lucent is present between the glandular stroma which is composed of dense connective tissue and the endpieces.  相似文献   

14.
Naked‐backed bats of the genus Pteronotus (family Mormoopidae) occur in the Neotropics from Mexico through northern South America. These are relatively small‐sized insectivorous species that frequently roost in caves. Eight specimens of naked‐backed bats (Pteronotus parnellii) were live‐trapped in Suriname and one in Cuba (P. quadridens). Their parotid glands were fixed in an aldehyde mixture designed for field work and postfixed in the laboratory with osmium tetroxide. Tissues were further prepared for electron microscopy by conventional means. The parotid glands of the two species of Pteronotusclosely resemble each other except for the substructure of their serous secretory granules. Serous granules in P. parnellii are bizonal, with a moderately dense inner matrix and an outer, denser corona or crescent. The matrix is occupied by laminae, flakes, and filaments in random array. In contrast, serous granules in P. quadridens consist of a uniform matrix that contains dense, usually stacked toroids or tubules either in random array or packed in bundles. A parotid gland from one specimen of P. parnellii contained an endpiece that consisted of cells that contained giant (up to 9 μm in diameter) serous granules. Serous cells in both species contain aggregates of small, uniformly dense, rod‐like, membrane‐delimited organelles as well as occasional bundles of cytofilaments. The endpieces are separated from intercalated ducts by a ring of granulated cells that contain secretory granules that often have a bull's‐eye configuration. Intercalated and striated ducts are typical in appearance, except that many of the cells in the latter contain small, dense secretory granules in their apical cytoplasm. The parotid glands in the two species of naked‐baked bats differ slightly in terms of acinar secretory granule ultrastructure, but otherwise are fairly conservative. It is thought that the glands in these particular bats might represent the “basal” condition of the salivary glands of insectivorous bats and thus can serve as a reference point for making comparisons to the highly diversified (in terms of diet) phyllostomid bats. Anat Rec 255:105–115, 1999. © 1999 Wiley‐Liss, Inc.  相似文献   

15.
The anterior medial glands lying in the submucosa of the rat nasal septum were studied by light and electron microscopy. The glands consist of a single long duct, which is studded with numerous solitary acinar formations connected perpendicularly to the main duct by short intercalated ducts. Proximal acini (those furthest from the stoma of the main duct) consist of typical serous cells with many dense secretory granules and an extensive rough endoplasmic reticulum. The most distal acini consist of cells whose major feature is the enwrapment of each mitochondrion by a cisternal profile of rough endoplasmic reticulum. Myoepithelial cells are absent from proximal acini, but are abundant on distal acini. Intracellular nerve terminals are extremely common, particularly in distal acini. The main ducts resemble, to a degree, the striated ducts of salivary glands.  相似文献   

16.
The excurrent duct system of the rat submandibular gland consists of a number of distinct segments. Using the direction of salivary flow as a reference point, these segments are, in order, intercalated duct, granular convoluted tubule, striated duct, excretory duct, main excretory duct (MED), and salivary bladder (which is an expanded portion of the MED). Because these ducts (with the exception of the MED and the salivary bladder) are encased in secretory endpieces, they are difficult to locate and to observe by scanning electron microscopy. A simple method has been devised to rid the gland of these obscuring endpieces so that the detailed architecture of the duct system can be examined. Rat submandibular glands were fixed initially by vascular perfusion with half‐strength Karnovsky's fixative. The connective tissue capsule was removed from extirpated glands and the glands remained in fixative for varying lengths of time. For our purposes, a 30‐minute immersion in the aldehyde mixture was optimum. After the sublingual gland was removed, the submandibular gland was softy struck with forceps having rounded tips, then shaken in fixative or buffer. The tissue that remained was postfixed in osmium tetroxide. This method results in the complete divestment of nonductular parenchyma from the rat submandibular gland, leaving the duct system clean and ready for microscopic examination. Anat Rec 254:74–75, 1999. © 1999 Wiley‐Liss, Inc.  相似文献   

17.
Summary The Harderian gland of the North American opossum (Didelphis virginiana) is large and well developed, despite the absence of a nictitating membrane in the adult of this species. The elongate glands are surrounded by a delicate connective tissue capsule from which thin septae extend, subdividing the gland into numerous lobules. The secretory units of the opossum Harderian gland are drained by a well defined but not extensive intralobular and interlobular duct system. Most of the secretory end pieces consist of tubuloalveolar units with widely dilated lumina filled with secretory product. Numerous intact lipid vesicles suspended within an amorphous material constitute the luminal contents. Cells lining the tubuloalveolar secretory endpieces are usually columnar in shape, and characterized by numerous lipid-containing secretory vesicles and aggregations of polytubular complexes 40–60 nm in diameter. In addition, these cells contain numerous large irregularly shaped mitochondria, whose matrix is of considerable electron density. Intralobular and interlobular ducts are lined by electron-lucent epithelial cells that lack both the lipid-containing vesicles and the large mitochondria, although typical smaller mitochondria are found scattered within the cytoplasm. Both secretory endpieces and ductal elements are invested by an abundance of myoepithelial cells. A second, smaller serous type of secretory unit may occur near the centre of some Harderian gland lobules. In these units secretory tubules and acini are compactly arranged surrounding a narrow lumen. Serous cells are pyramidal in shape and the cytoplasm is characterized by numerous electron-dense secretory granules and scattered profiles of rough endoplasmic reticulum. Basolateral cell membranes show extensive infoldings and intercellular canaliculi are present. The overall size of cells forming the serous secretory units is much less than that comprising the tubuloalveolar secretory endpieces.  相似文献   

18.
The characteristics of the submandibular glands of ageing Wistar rats were studied using light and high-resolution scanning electron microscopy (HRSEM) methods. For light microscopy, the samples were fixed in Bouin solution and embedded in paraffin. Sections were stained with hematoxilin-eosin and Azo-Carmin. For conventional scanning electron microscopy, the tissues were fixed in modified Karnovsky solution, and treated with NaOH solution for 3-4 days. The O-D-O method was used for HRSEM. The samples were fixed in 2% osmium tetroxide, macerated in diluted osmium and dehydrated in an increasing series of ethanol. The samples were dried in a critical point dryer, coated with gold-palladium and examined in a Hitachi high-resolution scanning electron microscope, S-900. The results showed that submandibular glands with lobules are separated by connective tissue septum. The acinar formations and the ducts, revealing the serous and mucous cells were observed. After fracture in liquid nitrogen and treatment with NaOH solution to remove the cellular components, the original disposition of the collagen bundles fibers were revealed corresponding to the round, oval or irregular acinar and ductal structures. In the cytoplasm, organelles such as mitochondria, rough endoplasmic reticulum, Golgi apparatus and serous and mucous secretory granules were observed localized in the apical portion in three-dimensional HRSEM images. The serous secretory granules presented different sizes and shapes showing the modifications which occurred in the ageing rats. The striated duct cells revealed the presence of the secretory cells and mitochondria in parallel disposition. The mitochondrial cristae were noted in three-dimensional aspects. The lumen presented numerous cytoplasmic microprojections. The lumen of excretor ducts are covered by polygonal epithelial cells containing numerous microplicae.  相似文献   

19.
The tent-building bat, Uroderma bilobatum, is a small, frugivorous phyllostomid bat with a broad neotropical distribution. Generally found in humid forest, this bat lives in small groups that create daytime “roosts” from large leaves of a variety of tropical plants. Fruit eating engenders a variety of ecological and physiological challenges for bats, some of which could require adaptive features in their salivary glands. The parotid salivary glands of Uroderma bilobatum were prepared for transmission electron microscopy by using methods that have become standard for field work. The parotid gland is extremely unusual in structure. Although the secretory endpieces still produce serous granules with a complex substructure, they are modified into quasi striated ducts. Their basal folds, which are extensive, occasionally harbor some vertically oriented mitochondria, imparting a resemblance to striated ducts. Other evidence for the endpiece origin of these parenchymal components is a well-developed system of intercellular canaliculi, structures that never occur in bona fide striated ducts. The long but sparse intercalated ducts consist of two types of cells, each of which elaborates a modest number of secretory granules of differing substructure. Striated ducts are of conventional morphology, except that a few dark cells shaped like wine glasses are present in their walls. The striated duct cells produce no secretory granules, but their apical cytoplasm may contain some small, empty vesicles. Capillaries lie in longitudinal grooves in the base of the duct cells, an arrangement that might enhance electrolyte exchange. Excretory ducts consist of simple cuboidal epithelium composed of cytologically unspecialized cells that sometimes includes a dark cell. It was concluded that salivary glands could have a major role in adapting species to acquire nutrients from marginal sources, such as tropical fruits, which have a low protein and sodium content. The unusual parotid acinar cells in Uroderma bilobatum are discussed in the context of salivary pH and buffering capacity. Comparisons are made with four other bat species, including an insectivorous species with a salivary pH > 8.0 and a very high buffering capacity, an intermediate species, and a fruit bat with acidic-stimulated saliva and very low buffering capability. Such interspecific comparisons provide a foundation for hypothesizing that ultrastructural features of the acinar cell basolateral membranes and intercellular canaliculi correlate with differences involving Na+/H+ exchangers and release of HCO3 and, thus, are associated with the species differences that are important to diet and nutrient acquisition. Anat. Rec. 252:290–300, 1998. © 1998 Wiley-Liss, Inc.  相似文献   

20.
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.  相似文献   

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