Ultrastructural Features of the Bovine Cecal Mucosa

The cecal surface epithelium of cattle was lined entirely by columnar cells except near the openings of the glands where a few partially depleted goblet cells were encountered. Surface columnar cells with pale cytoplasm, indented (sometimes dome-shaped) apical border and irregular microvilli, were also found near the gland orifices. Surface columnar cells -near the openings of the glands contained large cytoplasmic vacuoles and lysosomal-like bodies. Near the extrusion zone, however, the columnar cells contained highly indented and apically displaced nuclei. The glands were usually long and straight and lined by an epithelium concisting mainly of undifferentiated and goblet cells. There were few entero-endocrine and non-epithelial cells (intra-epithelial lymphocytes and globule leukocytes). Paneth cells were absent. The undifferentiated cells contained many free ribosomes and apical secretory granules. Some of these cells were undergoing mitotic division. Goblet cells exhibited a typical brandy-glass appearance and showed dark and light mucigenous granules. Endocrine cells with polymorphic secretory granules and cells with more uniform secretory granules were identified in the basal part of the epithelium. Globule leukocytes and intra-epithelial lymphocytes were usually encountered near the basal part of the epithelium. The lamina propria was highly cellular. It contained many plasma cells, mast cells and small lymphocytes, and few eosinophils, neutrophils and globule leukocytes. Some of the plasma cells contained large, dense Russell bodies within the cisternae of the rough-surfaced endoplasmic reticulum. The neutrophils displayed distinct populations of small and large cytoplasmic granules. Some of the eosinophilic granules showed narrow crystalline cores. Large lymphocytes were found in the lamina propria, but occurred less frequently than small lymphocytes.     

Granular cell variants in a rat schwannoma. Evidence of neurogenic origin of granular cell tumor (myoblastoma).

A large, intraabdominal rat schwannoma had numerous granule-containing cells cytologically identical to cells of granular cell tumor (myoblastoma). The small eosinophilic granules stained positively by the periodic acid-Schiff (PAS) reaction, with intensity not reduced by diastase pretreatment. Granules stained positively with the Tibor Pap silver impregnation for reticulin and by electron microscopy were identical to myoblastoma cell granules. The nuclei of granular cells were morphologically identical to those of the neoplastic Schwann cells. The granular cells were in numerous foci within the tumor, frequently were seen in mitosis, and possessed an extremely variable volume of cytoplasm. They seemed to evolve from neoplastic Schwann cells. Cells with only a narrow perinuclear rim of granular cytoplasm were of the same size and general configuration as adjacent neoplastic Schwann cells, while cells with increasing volumes of granular cytoplasm were increasingly swollen and round. One area of the tumor was composed almost entirely of such large cells and was histologically identical to classic granular cell tumor.     

Thymic carcinoma of the thymic hormone secretory type in a cow.

An 8-year-old Holstein cow had tumor nodules and enlarged lymph nodes in the mediastinum, and metastatic tumor masses in the pelvic cavity. The neoplastic cells were characterized by squamous features and intracytoplasmic vacuoles carrying microvilli, some of which contained periodic acid Schiff-positive globular cores, but tubular structures or goblet cells were absent. Many neoplastic cells stained positively for keratin, and occasional cells were positive for thymosin. The presence of secretory granules in the cytoplasm was confirmed by electron microscopy. This neoplasm was considered to be of thymic hormone-secreting epithelial cell origin.     

Morphological Study of Bovine Pregnant Corpus luteum Cells

The bovine pregnant corpus luteum was examined morphologically, to clarify the appearance and properties of the intramitochondrial bodies (IMB) in mitochondria of the large luteum cell (LLC). The incidence and diameter of the IMB (200–900 nm) showed a tendency to increase with the advance of pregnancy. Histochemically, the IMB reacted positively with protein, and immunohistochemically, they reacted IMB with 11 α-hydroxyprogesterone-1-11 succinyl-bovine serum albumin (P-BSA). The IMB seemed to combine with protein, and these granules did not undergo exocytosis. The cytoplasm of LLC contained another type of small electron-dense granules that were 150–200 nm in diameter, had an orifice for secretion, and reacted with relaxin. Small luteum cells (SLC) revealed crystalline-like inclusions. It is suggested that these inclusion cells participate in the synthesis of steroids.     

Ultrastructural and ultracytochemical cyclic changes in the bovine uterine tube (oviduct) epithelium.

Ultrastructural and ultracytochemical features of the uterine tube (oviduct) infundibulum were studied in 8 Hereford cows, which were slaughtered in pairs on days 1 (estrus), 3, 9 or 10, and 18 of the estrous cycle. Fibrous granules (60 to 80 nm), which are supposedly related to basal body replication, were observed in the apical cytoplasm of ciliated cells. Close association between basal bodies and fibrous granules was apparent, especially during the follicular phase. Cilia were observed throughout of estrous cycle, although degeneration of cilia was not observed at any phase of the cycle. Prominent, striated rootlets were observed during both the follicular and luteal phases of the cycle. Maximum secretory cell differentiation was apparent during the follicular phase, at which time these cells were characterized by having a well-developed, rough endoplasmic reticulum with dilated cisternae, numerous ribosomes, and secretory granules of varied size and density. A prominent feature of the secretory granules was their membranous structure, consisting of concentric lamellae of equal dimensions. During the luteal phase, cytoplasmic protrusions were prominent, and extruded nuclei along with other cytoplasmic organelles were present in the tubal lumen. The presence of a well-developed, rough endoplasmic reticulum and numerous secretory granules during the follicular phase indicates that secretory activity of the uterine tube infundibulum may be stimulated by estrogen. During estrus, the cytoplasm of the stromal cells displayed abundant, rough endoplasmic reticulum with dilated cisternae. The increased and extensively dilated rough endoplasmic reticulum at the time of estrus probably indicates increased protein synthesis by the stromal cells. The presence of adenosine triphosphatase activity on the membrane of cilia suggests that this enzyme is involved in energy-forming reactions related to the vigorous action of cilia. The presence of acid phosphatase activity on the cell membrane of the epithelium, microvilli, and secretory granules may indicate involvement in the secretory mechanism of the cell.     

Histology, Ultrastructure and Carbohydrate Histochemistry of Pig Carpal Glands

The morphological differences between two types of secretory cells (clear and dark) from pig carpal glands were examined. The main difference is the presence in the dark cells of secretory granules of moderate electron density, made up of acidic and neutral glycoproteins. The possible functional purposes of the carpal glands and of glycogen present in both cell types are also discussed.     

A light and electron microscopic study of a normal adrenal medulla and a pheochromocytoma from a horse.

The outer medullary (juxtacortical) zone of a normal equine adrenal gland had columnar chromaffin-positive cells arranged with their long axes perpendicular to fine vascular channels. The deeper medullary regions were composed of smaller irregularly round to polygonal chromaffin positive cells in small packets. Both cell types contained two types of membrane-bound cytoplasmic secretory granules. Osmiophilic granules with a homogeneous core, crenated membrane and narrow submembranous halo predominated in the columnar juxtacortical cells. The rounder, central medullary cells contained predominantly electron dense granules with a wide irregular electron lucent space between an eccentric core and the granule membrane. In contrast, irrespective of cell type or zone, cells from a pheochromocytoma contained only one type of granule similar to that described for the juxtacortical region of the normal equine adrenal medulla. The tumor cells could be classified into three subtypes based on density of granule packing but the granules were morphologically similar in all tumor cells.     

Ultrastructural study of sheep lacrimal glands.

Sheep lacrimal glands are mixed glands, consisting of tubulo-acinar units succeeded by ducts of simple morphology. The secretory portions consist of three cell types: mucous, seromucous and serous, which may be intermingled in the same acinus or may form acini wholly made of only serous or mucous cells. Mucous cells show a rough endoplasmic reticulum that is reduced to a few cisternae located near the cell base and among the interstices of the secretory droplets. Mucous granules appear uniformly electron-lucent. Serous cells display a typical structure; serous granules can be uniformly electron-dense or composed of dense inclusions dispersed in an electron-lucent matrix. The seromucous granules have a bizonal substructure: a dense core is embedded in a highter matrix. Secretory acini are succeeded by intercalated ducts; the epithelium of these ducts gradually increases in height to form a kind of excretory duct, without the intervention of striated ducts.     

鹅胸腺APUD(样)细胞的超微结构

应用透射电镜在鹅胸腺内发现一种ＡＰＵＤ（样）细胞。这种细胞形态不规则,有突起伸入相邻细胞之间;胞核圆形,电子密度低,核仁明显;胞质内含有粗面内质网、线粒体等丰富的细胞器。其主要特征是含有大量的多分布于胞质一侧的膜包小分泌颗粒,呈圆形或椭圆形,大小不等,直径１１０～５５０ｎｍ,有些颗粒在界膜与内含物之间可见低电子密度的晕轮。根据其超微结构特征,可将颗粒分为３型：Ⅰ型颗粒为中等电子密度;Ⅱ型颗粒为均质状高电子密度;Ⅲ型颗粒在中等电子密度中含有一高电子密度的核芯。作者认为这种细胞属于内分泌细胞,并且很可能是分泌肽类激素的ＡＰＵＤ细胞。     

Intranasal tumor of the ethmoid olfactory mucosa in sheep.

Intranasal tumors (papillary adenomas or adenocarcinomas) of the ethmoid olfactory mucosa of sheep were investigated by light and electron microscopy. The fine structure of the tumor cells was characterized by the presence of numerous secretory granules. Viral particles, which were morphologically similar to a visna-maedi virus, were detected in all tumor tissues and in 3 of 4 cultures examined. The particles (about 97 nm) had an eccentrically located electron-dense core and numerous spikes on their surfaces. The RNA-dependent DNA polymerase activities in the tumor cells or the cultured cell from the tumor were greater than those in the normal intranasal tissues or the cultured cells from the choroid plexus. Viral particles similar to herpesvirus were also detected in 1 culture.     

Fine Structure and Peroxidase Activity of the Bovine Mandibular Gland Cells

The acini of the bovine mandibular gland consist of mucous and demilunar seromucous cells. The mucous cells contain electron-lucid mucigen droplets or mucoid masses, only rarely delimited by membranes. The cisternae of the RER communicate freely. Mitochondria are scarce. The seromucous demilunar cells contain considerably more granules, and perigranular membranes are far more common. Many granules have characteristic alternating electron opaque and less electron dense areas. The prominent RER appears to be associated with a peculiar labyrinth of interconnecting tubules. Mitochondria are numerous. Numerous myoepithelial cells are observed. The cuboidal cells of the intercalated ducts lack signs of secretory activity. The columnar cells of the striated ducts have extensive infoldings of the basal plasma membrane, associated with mitochondria. The cell apex contains many granulated vesicles. Endogenous lactoperoxidase activity could be demonstrated only in the demilunar cells, within the secretory granules, the RER, including the perinuclear cisternae, as well as the labyrinth mentioned above. A positive reaction could be observed over acinar lumina and in intercellular canaliculi. The possible role of peroxidase as a component of a bactericidal system of the bovine saliva is discussed.     

Ultrastructural features of the uterus in the sexually immature ostrich (Struthio camelus) during periods of ovarian inactivity and activity

The ultrastructure of the surface epithelium and tubular glands of the uterus in the immature ostrich is described. In ostriches with inactive ovaries the uterus is lined by a non-ciliated simple columnar epithelium, with basally located heterochromatic nuclei. Scanning electron microscopy revealed that these non-ciliated cells have a dense microvillous cover. A simple columnar to pseudostratified columnar epithelium, comprised of non-ciliated and ciliated cells, lines the uterus in birds with active ovaries. The ciliated cells possess a wide luminal region, which contains a nucleus and various organelles. An accumulation of secretory granules was observed in the apical regions of the non-ciliated cells, as well as in a few ciliated cells. In addition to non-ciliated and ciliated cells, a cell type with rarefied cytoplasm was also identified. These cells appear to correspond to calcium secreting cells identified in other avian species. The results of this study indicate that, although uterine differentiation is present in immature ostriches with active ovaries, the production of secretory product appears to occur mainly in non-ciliated epithelial cells.     

Immunohistochemical and histoplanimetrical study on the spatial relationship between the settlement of indigenous bacteria and the secretion of bactericidal peptides in rat alimentary tract

To clarify the regulatory mechanism by bactericidal peptides secretion, the secretion of bactericidal peptides was immunohistochemically and histoplanimetrically compared with the degree of Gram-positive/negative bacterial colonization throughout the rat alimentary tract. In the associated exocrine glands from the oral cavity to the stomach, no comparable differences were observed under the changes of development of indigenous bacterial colonies. In the small intestine, immunopositive granules for lysozyme and secretory phospholipase A2 (sPLA2) were markedly decreased, whereas immunopositive vacuoles in the Paneth cells were more increased at sites with hyper-development of indigenous bacterial colonies in the intervillous spaces than at sites with no or less development. No changes in exocrine glands were observed in the large intestine because of the constant existence of large quantities of bacteria. Gram-positive bacterial colonies on the mucosal surfaces were dominant from the oral cavity to the stomach. Gram-negative bacteria were dominant in the large intestine, and the distributions of both Gram-positive and negative bacteria were intermediate in the small intestine. These findings suggest that lysozyme and sPLA2 secreted from the Paneth cells contribute to the regulation of the proliferation of indigenous bacteria in the intervillous spaces of the small intestine, and that the inversion of distributions of Gram-positive and -negative bacteria in the alimentary tract might be caused by the secretion of lysozyme and sPLA2 in the small intestine.     

Histological observation of the proper gastric gland in Minke whale,Balaenoptera acutorostrata

To accumulate histological information of cetaceans, the proper gastric gland of Minke whales was examined by light and electron microscopic observation. A small number of mucous neck cells and a large number of chief and parietal cells were observed in the gland. At the body to basal portions of the gland, the ratio of chief cells to other cells seemed to be large compared to the neck portion. Transmission electron microscopy revealed that the chief cell had secretory granules with middle level of electron density, and that the parietal cell contained abundant mitochondria and intracellular canaliculi. The proper gastric gland of the Minke whales may appear to secrete large amounts of digestive enzymes and have high digestive activity.     

Regional and Cyclic Variations in the Ultrastructural Features of Secretory Cells in the Oviductal Epithelium of the Chinese Meishan Pig

The Chinese Meishan pig is prolific breed and it is considered that this pig has a capacity with higher rates of embryonic survival. The oviductal secretory cells may affect the embryonic development and survival. The aim of the present study was to investigate the ultrastructural features of secretory cells in the various regions of the Chinese Meishan pig oviduct during the follicular and luteal phases of the oestrous cycle. In the ampullar secretory cells, numerous secretory granules with moderately electron-dense matrices were present in the supranuclear cytoplasm and exocytosis of secretory granules was observed. The number of secretory granules was dramatically reduced in the ampullar secretory cells in the luteal phase. During the follicular phase in the fimbrial epithelium, the secretory cells contained rough endoplasmic reticulum and Golgi apparatus, but most cells had few small granules. In the luteal phase, the secretory cells in the ampullar and fimbrial epithelia extended beyond the luminal border of the ciliated cells. In the isthmus, many granules were present in the cytoplasm of secretory cells throughout the oestrous cycle, but the number of secretory granules was reduced in the luteal phase. The cytomorphometric data revealed that the height of ciliated cells decreased substantially in the fimbriae and ampulla at the luteal phase, while that of non-ciliated cells was less affected. These results suggest that the drastic reduction of cell height of ciliated cells cause the extrusion of most secretory cells beyond the ciliated cells in the fimbriae and ampulla during the luteal phase. In summary, our ultrastructural observations of Chinese Meishan pig oviduct revealed marked cyclic changes in the ultrastructural features of secretory cells. In particular, the ultrastructural features and the numbers of secretory granules were distinctive for each particular segment. These findings should provide insight into the regional and cellular differences in functions of secretory cells of the Chinese Meishan pig oviduct.     

Ultrastructure of canine, feline, and bovine mast cell neoplasms

Biopsy specimens were collected from skin or spleen from 8 dogs, 7 cats, and 1 cow with mast cell neoplasms. Following histopathologic grading, the neoplasms were examined by transmission electron microscopy with the intention of reviewing their fine structure and recording new findings. For 2 feline specimens, short-term cell cultures were established, and adherent cells were fixed in situ and examined with the electron microscope. In addition to the usual array of mast cell organelles, including Golgi apparatus, secretory granules, mitochondria, vesicles, tubules, microfilaments, and ribosomes, important findings included coarse interdigitation of cytoplasmic projections between adjacent mast cells; intracytoplasmic parallel stacks of 10 nm diameter filaments as well as parallel arrays of coarse, 120 to 150 nm diameter tubules; the appearance of coated vesicles and caveolae on cell surfaces; the appearance of endocytosed erythrocytes; and the formation of giant secretory granules.     

Hatching Gland Cells of Trout Embryos as the Target of Positional Information

HGCs were found in the head epidermis, yolk sac and pharynx epithelium of trout embryos. These cells usually appear in clusters, closely related positionally to neighbouring cells. The differentiation and specialization of HGCs seem to be mainly dependent on cell-cell interactions, which provides, in part, the positional information necessary for the cells to differentiate and localize in the appropriate place. The final secretory process is the result of a sequence of events by which the maturation of enzymatic granules occurs. The electron-density of the granules varies according to the proximity of the secretory stage. Exocytosis of the secretory granules were observed. After secretion, each HGC undergoes cellular death by apoptosis (programmed cell death).     

雌性中华鳖输卵管精子储存结构的研究

应用光镜和电镜技术,系统观察雌性中华鳖输卵管精子储存情况,显示与精子储存有关组织结构与细胞形态。结果表明,精子储存在雌性中华鳖输卵管的蛋白分泌部后部至子宫部,但各段的组织结构及精子储存量存在一定差别。蛋白分泌部后部上皮较发达,由典型的高柱状纤毛细胞和分泌细胞构成,固有膜中腺体多为泡状腺。上皮和腺体中含有大量高密度的膜性分泌颗粒,此段只有少量的精子储存。峡部较窄且固有膜内无腺体,上皮排列紧密并呈迷路样迂回分布,上皮细胞内高电子密度分泌颗粒成团集中分布在核上方。峡部管腔中分布着大量的精子,靠近管腔的精子或精子头部嵌入上皮纤毛之间或顶端凹陷的胞质中,且精子嵌入部分的细胞结构保持完整。子宫前部形成垂直于管腔的储精小管(SST),子宫上皮及此段SST上皮的分泌颗粒电子密度不均,含高密度电子致密斑,腺体中的分泌颗粒也呈现不同的内部结构。子宫部及SST的管腔中储存有大量精子。这些区段复杂的细胞结构及分泌活动,可能在精子储存中发挥重要作用。     

Ultrastructure of the platypus and echidna mandibular glands

The secretory units of the platypus and echidna mandibular glands consist of a single serous cell type. Secretory granules within the cells of the platypus mandibular gland stained intensely with the periodic acid-Schiff staining procedure but failed to stain with Alcian Blue, suggesting the granules contained neutral glycoproteins. Secretory granules within the mandibular glands of the echidna failed to stain with the methods used indicating little if any glycoprotein was associated with the secretory granules. Ultrastructurally, secretory granules of the platypus mandibular gland were electron dense with a central core of less electron-dense material and were membrane bound. In contrast, those of the echidna presented a lamellated appearance and also were limited by a membrane. These secretory granules appeared to form as a result of concentric layering of lamellae within cisternae of the Golgi membranes. The intralobular ductal system of the platypus was more extensively developed than that of the echidna. The striated ducts of both species were characterized by elaborate infoldings of the basolateral plasmalemma and an abundance of associated mitochondria.     

Gross,Histological and Ultrastructural Features of the Bulbourethral Gland in the Greater Cane Rat (Thryonomys swinderianus)

The present study examines the structure and ultrastructure of the bulbourethral glands in 10 sexually matured male greater cane rats raised in captivity. Following anaesthesia, the rats were perfusion‐fixed transcardially and the bulbourethral glands dissected out. Upon morphologic and morphometric analysis, the Cowper's glands were observed to have an average volume of 0.24 ± 0.08 ml, a diameter of 6.3 ± 0.6 mm and weighs 0.199 ± 0.06 g. The paired, gourd‐shaped tubuloalveolar glands were surrounded by dense connective tissues and separated into lobules by capsular septae. Each lobule consists of endpiece/secretory units and excretory ducts lined by simple glandular epithelium and pseudo‐stratified epithelium, respectively. The round end pieces consisted of 8–10 pyramidal to columnar epithelial cells with flattened, basally located nuclei and granule‐filled cytoplasm that bounded a narrow glandular lumen. The striking ultrastructural features of these secretory cells were the presence of some granules with uniform electron density and those with regions of lesser density as well as the absence of secretory vacuoles. Another unique characteristic of these secretory granules is the presence of electron dense strands radiating from their surfaces. The apical surfaces of the cells were also studded with abundant microvilli. From the findings, the structure of bulbourethral glands in the greater cane rat shows more resemblances to that of humans than to its rodent phylogeny. These findings serve as additional knowledge in the structural interpretation of the bulbourethral gland and its secretory products.