Ultrastructural and histochemical observations on secretory phenomena in the resting human mammary gland

Ultrastructure and histochemistry of clinically normal appearing tissue and secretions of non-lactating human mammary glands have been investigated in order to document and analyse secretory phenomena in the resting gland. The material studied originated from women of different ages (18-74 years) who underwent plastic surgery or surgery for various disorders of the breast. The epithelia of small ducts and of alveolar enlargements as well as acini contained moderate amounts of mitochondria and of cisterns of the rough endoplasmic reticulum; the transcisterns of the Golgi apparatus which were surrounded by smooth and coated vesicles, exhibited modest dilatations, the number of lysosomes increased with age; regularly glycogen particles and bundles of intracellular filaments (phi 5 nm) were to be observed. Typical casein vesicles and stages of apocrine secretion of milk fat globules were not seen. The following features indicated secretory activity: differently sized vesicles and granules with flocculent, dense, or light contents were regularly to be seen in the apical cytoplasm often immediately below the apical plasma membrane of the epithelia of the small ducts and even more frequently in the alveolar enlargements. Secretory products of fine granular or filamentous structure, probably containing proteins, were frequently found within the lumen. Different types of lipid and liposome-like particles were detected both in intracellular localization as well as in ductal lumina. As demonstrated by lectin histochemistry the secretory products also contained a considerable amount of carbohydrate components. The composition of the secretory products of the resting gland is of clinical interest since the chronical deposition of secretions, which among others possibly contain enzymes producing oxygen radicals, may lead to pathological changes of mammary gland tissue.     

Ultrastructural observations on the central innervation of the guinea-pig pineal gland

Summary In the present study the central innervation of the guinea-pig pineal gland was investigated. The habenulae and the pineal stalk contain myelinated and non-myelinated nerve fibres with few dense-cored and electron-lucent vesicles. Some myelinated fibres leave the main nerve fibre bundles, lose their myelin-sheaths and terminate in the pineal gland. Although direct proof is lacking, the non-myelinated fibres appear to end near the site where the bulk of the myelinated fibres are located. Here a neuropil area exists where synapses between non-myelinated fibre elements are abundant. Neurosecretory fibres were also seen. The results support the concept of functional interrelationships between hypothalamus, epithalamus and the pineal gland.     

Ultrastructural observations on human cerebral capillaries in organ culture

The use of an organotypic-in the strictly literal meaning of the word, nervous tissue culture device has allowed the identification and ultrastructural study of various types of developing capillaries in human cerebellum and olfactory bulb in vitro. Most capillaries were similar to those already described by other authors or by us, in human or animal embryos and fetuses. Large Type I Capillaries. Their luminal diameters were greater than 8 microns. The basement membranes were thin and discontinous. Numerous interendothelial junctions were either plate-like attachments or contained pentalaminar zones. Type II Capillaries. Their lumina were between 2 and 8 microns in diameter. The basement membranes were wider than those of type I capillaries and were sometimes continuous. The interendothelial junctional complexes of type II capillaries included pentalaminar portions. Many simple or complex vascular sprouts (type IV and V capillaries) had small or non-patent lumina. Their basement membranes were absent or very thin and discontinuous. Their interendothelial junctions were similar to those of type I capillaries. Some of the less frequently encountered capillary types seen in developing human nervous tissue were absent in culture. Some pathological features were seen-especially in long-term cultures-in type I and II capillaries containing degenerating blood cells or processes sometimes obviously related to histiocytic cells. They consisted mainly of an accumulation of microfilaments and modifications of the rough endoplasmic reticulum in the endothelial cells. These pathological changes did not modify the main characteristics of the capillaries. The origin of the vascular sprouts, the exact nature of the interendothelial junctions and the significance of the pathological changes are discussed. This model may prove useful for the study of cerebral vasculogenesis, the development of the blood-brain barrier and the physiological or pathological properties of the human brain capillaries in tissue culture.     

Ultrastructural observations at pineal gland capillaries in four rodent species.

The fine structure of the capillaries of the pineal glands of the rat, mouse, chinchilla, and ground squirrel were investigated. The pineal endothelial cells in the rat, mouse and ground squirrel were often composed of attenuated cytoplasmic portions which contained numerous fenestrations, in contrast to pineal capillaries in the chinchilla which were lined by thick non-fenestrated endothelial cells. Marked morphological differences were also apparent in terms of the types of vesicles within the cytoplasm and abutting on the cell surface of pineal endothelial cells from the various species investigated. The interendothelial junctions exhibited remarkable species differences with the chinchilla pineal possessing typical tight endothelial junctions while those in the rat, mouse and ground squirrel lacked such endothelial cell associations. Generally, capillary lining cells in the chinchilla pineal resembled similar cells within the brain, while endothelial cells in pineal glands of rat, mouse and ground squirrel were more typical of those found in other endocrine organs. Species differences in the structure of the pineal capillaries may represent physiological differences as well.     

Ultrastructural morphometric observations on serial sectioned human blood platelet subpopulations

The relationships between the volume of human platelets and their cytoplasmic organelles were studied by morphometric analysis. Platelets were separated into four density-dependent subpopulations on an arabino-galactan gradient. In vitro activation of platelets was effectively prevented by maintaining them at a constant ambient temperature of 37 degrees C. Serial sections were cut through platelets, morphometrically analyzed and the platelets reconstructed. The volumes of the individual platelets and their constituent granules, mitochondria and open canalicular systems (OCS) were calculated. Individual organelles were counted. The mean volumes of the platelets of the subpopulations decreased significantly as density decreased (p = 0.01). Also, as the density of platelets decreased, there was a decrease in the mean unit volume of their granules (p = 0.003). In contrast, independent of platelet volume or density, the OCS occupies about 10% of the platelet volume. These findings indicate that it is possible to prevent in vitro platelet activation by maintaining their environment at 37 degrees C. Our study confirms the direct relationships between platelet volume and density; and platelet density and granule content. There is no ready explanation for the constant relationship between platelet volume and that of the OCS.     

Ultrastructural observations on choroid melanoma

Twelve melanoblastomas of the choroid of different histological types have been studied in the semi-thin sections and at transmission electron microscope. There have been also observed at scanning electron microscope. The ultrastructural findings show some differences in the main cellular types as observed at light microscope by Callender (spindle-shaped cells A and B and epithelioid). In the epithelioid and spindle-shaped B cells a higher number of ribosomes and of mitochondria and large, polymorphous, often multiple nucleoli with reticular structure are observed. There findings may be related to a greater metabolic activity and anaplastic tendency of these cells. Moreover in spindle B - and epithelioid - cell types atypical melanogenesis and nuclear bodies are particularly evident. Scanning electron microscope show well developed cytoplasmic extensions in spindle cells.     

Ultrastructural observations on differentiating human preadipocytes cultured in vitro

A cell type, preadipocytes, isolated from the stroma of adult human adipose tissue appears capable of differentiating, in culture, into a cell with morphological features similar to that observed in terminally differentiated human adipocytes cultured under similar conditions. During this process of differentiation, preadipocytes develop extensive rough endoplasmic reticulum with prominent cisternae, the chromatin of most nuclei becomes decondensed and lipid bodies accumulate to levels observed in cultured adipocytes. Fibroblasts derived from non-adipose tissue do not undergo the same morphological changes when cultured under similar conditions.     

Ultrastructural and histochemical observations on spermathecal gland of Dytiscus marginalis L. (Coleoptera)

Summary Histochemical studies have been carried out on the composition of feltwork and tubule in the spermathecal gland cells of Dytiscus marginalis L.These extracellular structures represent the secretion-collecting apparatus of the cells of the spermathecal gland, through which the secretion passes externally into the lumen of the spermatheca.The presence of a particular protein, resilin, also called arthropod elastin, at the level of the tubule and the feltwork, and of neutral polysaccharides present only in the feltwork have been demonstrated.Special consideration is given to the silver-methenamine reaction, the results of which have been interpreted in terms of the amino-acid composition of resilin itself.The behavior of this reaction, as a function of the type of fixation solution employed, is also discussed.     

Ultrastructure of the ferret sublingual gland

The sublingual glands of 2 male and 2 female adult ferrets were examined using electron microscopy. The secretory end piece consisted of mucous tubules, serous and mixed acini. The mucous cells showed two different types of granules. The serous cells contained electron-dense secretory granules. The duct system entirely comprised excretory ducts.     

Ultrastructural observations on the formation of follicles in the human fetal thyroid

Pituitary somatotrops were localized in four species from the genus Oncorhynchus using an antiserum to chum salmon (Oncorhynchus keta) growth hormone. The antiserum cross-reacted specifically with the acidophils in the caudal pars distalis of all species tested. Corroborative immunodiffusion studies were also conducted with pituitary homogenates from the same species. Immunological identity of the GH molecule was observed for all species tested.     

Ultrastructural observations of the effect of nitrogen mustard on human chromosomes]

The authors observed in electronic microscopy the methyl-bis-beta chlorethylamine action (nitrogen mustard) on normal human chromosomes. The effects were obtained in vitro after colchicine blocking and on grids after fixation. The action is remarkable on the fiber and on the chromatid's structure.     

Ultrastructural observations on cortical granules in human follicular oocytes cultured in vitro

The fine structure, distribution, and fate of cortical granules in human oocytes cultured in vitro are reported. Follicular maturation in women with blocked Fallopian tubes was induced by clomiphene citrate and human chorionic gonadotropin, and preovulatory eggs were obtained by improved methods of laproscopy and oocyte recovery. These oocytes were then inseminated and cultured in a modified Ham's F10 medium for 3 to 72 hr to assess their fertilizability. Cortical granules were observed in all 17 unfertilized oocytes investigated, which had completed various stages of meiotic maturation. A marked increase in their numbers was observed in oocytes cultured for 3 to 6 hr. There was no evidence of spontaneous cortical granule release in any of the oocytes studied. It is concluded that cortical maturation expressed by proliferation of cortical granules is as significant a criterion as nuclear maturation in assessing maturity and fertilizability of oocytes cultured in vitro. A short sojourn in culture before insemination could improve chances of normal fertilization and embryo development, which has been recently achieved in our laboratory.     

Ultrastructural observations on oogenesis in Drosophila

The ultrastructure of the follicle cells and oocyte periplasm is described during the stages of oogenesis immediately prior to, during, and immediately subsequent to, vitellogenesis. A number of features have not been described previously in Drosophila. Some yolk appears prior to pinocytosis of blood proteins. However, most of the protein yolk forms while the periplasm is filled with micropinocytotic invaginations and tubules derived from the oolemma. These tubules retain the internal layer of material characteristic of coated vesicles and are found to fuse with yolk spheres. No accumulation of electron-dense material in the endoplasmic reticulum or Golgi of the oocyte is found. Both trypan blue and ferritin are accumulated by the oocyte. The follicle cells have an elaborate endoplasmic reticulum during the period of maximum yolk accumulation. Adjacent cells are joined at their base by a zonula adhaerens, forming a band around the cells, and by plaques of gap junctions. Gap junctions are also present between nurse cells and follicle cells. During chorion formation, septate junctions also appear between follicle cells, adjacent to the zonula adhaerens.     

Ultrastructural observations of human and mouse oocytes treated with cryopreservatives

The effects of the cryopreservative agents dimethylsulfoxide (DMSO) and propanediol (PROH) on mature human and mature mouse oocytes have been examined with transmission electron microscopy. Treatment of CD-1 mouse oocytes and human preovulatory oocytes in a stepwise manner with either DMSO or PROH up to 1.5 M appears to trigger the exocytosis of 70-80% of the cortical granules in all oocytes. Successive stages in premature dehiscence, including a loss in granule electron density, fusion of the granule-limiting membrane with the oolemma, and extrusion of the cortical granule core into the perivitelline space, have been observed in all human oocytes studied. In addition, all human DMSO- and PROH-treated oocytes exhibited crypt-like invaginations and clusters of endocytic vesicles that subtend the oolemma. The presence of these crypts and pinocytotic vesicles in treated oocytes may suggest a mechanism for the retrieval of cortical granule membrane that is inserted into the original plasmalemma during exocytosis. The paucity of cortical granules in treated mouse and human oocytes as it potentially relates to an impaired ability to elicit the cortical reaction at fertilization is discussed.     

Ultrastructural,cyto- and biochemical observations during turnover of plasma membrane in duck salt gland

Summary The mechanism of plasma membrane turnover was investigated using the duckling salt gland as a model system. Feeding fresh water to saltstressed ducklings results in a decrease in the Na, K-ATPase in salt gland to nonstressed levels in about 7 days, as measured by ATP hydrolysis and ³H-ouabain binding. Electron micrographs reveal that this is accompanied by a decrease in plasma membrane infoldings on the basal and lateral borders of gland secretory cells. Simultaneously there is an increase in filamentous material and a rise in acid phosphatase and peptidase activities in these cells. Cytochemistry shows that the acid phosphatase activity is mostly associated with the basal or basolateral regions of secretory cells. These observations could indicate that the removal of plasma membrane components is accomplished by internalization and digestion within the secretory cells.