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Query: UMLS:C1275122 (TEM)
 21,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The epithelial cells of the human parotid main excretory duct (Stensen) were studied by transmission (TEM) and scanning (SEM) electron microscopy through a variety of procedures that allowed the visualization of their three-dimensional microanatomy. Stensen's duct in humans is lined, in its distal portion, with a pseudostratified epithelium with tall principal cells and smaller basal cells, while the epithelium becomes progressively stratified cylindrically toward the oral stoma. Goblet cells are scattered among the other epithelial cells. The principal cells exhibit, on their lateral surfaces, numerous flattened laminar folds probably involved in transporting processes. A well-developed smooth endoplasmic reticulum intermingled with mitochondria occupies the cellular apices. Some vesicles are recognized on the cytoplasmic surfaces of the apical and lateral plasmalemma when cytoplasmic organelles are removed. All these features are interpreted as being involved in the process of endocytosis. In both TEM and SEM, the principal cells show a relevant number of irregular apical protrusions that may represent a kind of apocrine secretion. Thus, with regard to function, the human Stensen's duct seems to modify the composition of saliva by processes of resorption and secretion, the latter coming from goblet cells as well. The basal cells have a surface microanatomy completely different from that of principal cells. They exhibit, in fact, only sparse microvillosities and smooth areas on their lateral aspect, while their stromal surface is greatly augmented by irregular thin ramified processes. The role of basal cells is also discussed.
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PMID:The main excretory duct (Stensen's) of the human parotid gland: a transmission and scanning electron microscope study. 856 34

The Wistar rats were treated with daunorubicin in the doses corresponding to average doses administered in humans. Analysis under TEM concerned changes in hepatocytes induced by the drug. The changes were compared with those observed in the liver when daunorubicin administration followed protective administration of tocopherol (vitamin E) and ascorbic acid (vitamin C) and when daunorubicin was given simultaneously with tocopherol and ascorbic acid. The results showed nucleus heterochromatin scattering, segregation of nucleolus granular and fibrillar components, swelling of mitochondria and myelin structures in them, segmental degranulation of rough endoplasmic reticulum and decreased number of glycogen granules. The studies led to the conclusion that daunorubicin hepatotoxicity was blunted in animals receiving simultaneously vitamin E and C, which indicates to assume that those antioxidants exert some protective effect on hepatocytes. Normalization of the changes 3 weeks after administration of the last dose suggests that most of the changes are reversible and do not result in chronic liver damage.
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PMID:Ultrastructural studies of daunorubicin hepatotoxicity in rats including protective effects of tocopherol and ascorbic acid. 895 42

Rats poisoned with cadmium acetate during 12 weeks, at a dose of 50 mg/dm3 given in drinking water, were treated with oxygen-ozone mixture as intraperitoneal injection during the last 10 days of the experiment, at a daily dose of 1 cm3 and ozone concentration 40 micrograms/cm3. The mixture was made of medical oxygen with a Bioozon U type apparatus produced by B. Prochazka GmbH, Germany, Reutlingen. Control groups included animals treated with the above mixture with no cadmium, and rats poisoned with cadmium, with no oxygen-ozone treatment. Liver and cardiac muscle were examined in TEM Philips EM 301. Morphological traits of a protective of the mixture against cadmium-poisoning were observed in both those organs. This was expressed as weaker destructive changes within the endoplasmic reticulum, basal cytoplasm and lysosome of the hepatocytes, and additionally as a stabilization of contractile apparatus fibres in the heart myocytes.
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PMID:Ultrastructural studies on organs of cadmium-poisoned rats treated with oxygen-ozone mixture. 907 58

The development of acinar and ductal cells of the mouse submandibular gland was studied using field emission SEM, conventional TEM and HVTEM methods. The specimens, at 15 and 18 days of gestation and 1, 3, 7, 14, 21, 30, 90 and 180 postnatal days were fixed in 2.5% glutaraldehyde solution in 0.1 M sodium phosphate buffer (pH 7.3). At 15 and 18 days of gestation, the structure of mouse submandibular gland contains acinar and ductal cells in proliferation. The cytoplasmic organelles such as mitochondria, granular endoplasmic reticulum and Golgi apparatuses are scattered in the cytoplasm. At 18 prenatal days only several acinar cells present immature secretory granules in the apical portion. In this stage the acinar and ductal cells are enveloped by bundles of fine collagen fibrils disposed in several directions. There are also numerous capillaries located closely to the acinar cell membranes. In the aging stages of 1, 3, 7, 14, 21, and 30 postnatal days, the histo-differentiation of acinar, intercalated and ductal cell components are observed. At newborn day one the cytoplasmic organelles start to place themselves around the nucleus. Several immature secretory granules are observed at day one, however, they increase in the aging days. At postnatal day 30, the cytoplasms of acinar and ductal cells are filled with a large number of secretory granules of different sizes. The stacks of granular endoplasmic reticulum and Golgi apparatus and some vesicles and free ribosomes are noted. The intercellular membranes are attached by desmosomes and cytoplasmic interdigitations. The luminal surface shows several small projections of microvilli. An electron-dense line of basement membranes followed by fine collagen fibrils are recognized. Delicate capillaries are found in the outer surface of acinar cells. At postnatal day 90 and 180 the acinar, intercalated and striated ductal cells reveal numerous secretory granules in the apical portion. The acinar cells showed basal nuclei and the parallel arrangement of granular endoplasmic reticulum. The mitochondria are located at the base of ductal cells showing a typical pattern of cristae. In these stages the intercellular digitations of cytoplasmic protrusions and desmosomes are also noted. The cytoplasm of myoepithelial cells are seen along the cell membranes. The spongy-like structures constituting the basement membrane are followed by bundles of fine collagen fibers.
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PMID:Field emission SEM, conventional TEM and HVTEM study of submandibular gland in prenatal and postnatal aging mouse. 915 Nov 34

This report on the fine structure of human oocyte is based on 20 years research where over 2000 eggs were examined by TEM in conjunction with our research on various methods of assisted reproduction. The eggs were routinely fixed in glutaraldehyde/osmium tetroxide, flat embedded in araldite, serially sectioned and examined by TEM. The oocytes were usually recovered after gonadotrophin stimulation. The general organisation of the mature human oocyte conforms to that of other mammals but has some unique features. The oocyte has the basic cell organelles such as mitochondria, lysosomes, two types of smooth endoplasmic reticulum (SER)-vesicular and tubular aggregates, multivesicular residual bodies, lipofuschin, microfilaments and microtubules. Golgi, RER and ribosomes are very rare and the egg has no yolk. It's surface has few microvilli, pinocytolic caveolae and 1-3 layers of cortical granules. The zona pellucida is composed of fine fibrils and granules embedded in an amorphous matrix and encloses a perivitelline space containing polar bodies. Remnants of corona cell junctions may be found at the oolemma. The metaphase II spindle is often oriented perpendicular to the surface and is barrel-shaped, anastral and lacks centrioles. Osmiophilic centrosomes are not demonstrable in human eggs since the maternal centrosome is inactive. The sperm centrosome organizes mitotic spindles of the embryo after fertilization, whereas in mice the maternal centrosome is active and dominant during cleavage. The stages of peri-ovulatory maturation and differences in oocyte structure during maturation are also presented. Oocytes ageing in culture show progressive swelling of vesicular SER culminating in vacuolation, denser mitochondria (clouding together or associated with vacuoles) peripheral conglomerations or centripetal migration of cortical granules and increased lysosomal activity. Prolonged culture also causes displacement and disorganisation of metaphase II spindles, loss of microtubules and consequent displacement of chromosomes. Evidently the cytoskeleton becomes disorganized. Some observations on oocyte maturation in vitro and spontaneous activation of oocytes are included.
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PMID:Ultrastructure of the human egg. 923 62

The effects of benanomicin A, a mannose-binding antifungal antibiotic, on yeast cells of Saccharomyces cerevisiae were studied by electron microscopy. Cytological studies using vital stain with methylene blue demonstrated that benanomicin A at 20 and 80 microg/ml killed buds in preference to parent cells. In confirmation, examination by TEM revealed that benanomicin A at 80 microg/ml damaged buds more severely than parent cells. The major effect on the ultrastructure was characterized by severe damage to the cell membrane. In addition, it caused expansion and vacuolation of the endoplasmic reticulum (ER), and partial fragmentation and disappearance of nuclear membranes. The membrane-disruptive activity of benanomicin A may be closely associated with its membrane affinity.
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PMID:Morphological alterations of Saccharomyces cerevisiae induced by benanomicin A, an antifungal antibiotic with mannan affinity. 965 68

Integrated transmission and scanning electron microscopic (TEM and SEM) techniques have provided the first detailed description of the ultrastructural features of the bovine cumulus-corona (CC) cells surrounding oocytes at the time of final maturation, zygotes and early cleaving embryos (2/4 to 6/8 blastomeres). TEM revealed the presence of rough endoplasmic reticulum and Golgi complexes in the cytoplasm of CC cells surrounding immature, mature and fertilized eggs, and also revealed an increasing amount of smooth endoplasmic reticulation membranes, lipid droplets and mitochondria with villiform and/or tubular cristae in the cytoplasm of CC cells during maturation and fertilization of the oocyte. In addition, a loss of cell-to-cell junctions between CC cells was evident. TEM also demonstrated that a few residual CC cells were still associated with early embryos and that these cells showed rather degenerative or apoptotic patterns, the latter pattern also observed on cells associated with fertilized eggs. SEM revealed that the complex of CC cells of immature oocytes was compact with narrow intercellular spaces, which progressively enlarged in size around mature oocytes. This phenomenon is mostly due to the production of abundant extracellular matrix. Immature CC cell complexes possessed characteristic long and filiform microvilli whereas the surface of CC cells surrounding mature oocytes showed numerous blebs and occasional large cytoplasmic protrusions as well as microvilli. Zygotes and early embryos were covered with a few polyhedral CC cells possessing scarce and short microvilli and a large amount of pleomorphic blebs. This study demonstrated a precocious luteinization occurring in bovine CC cells at ovulation until zygote segmentation, and this process was associated with a progressive apoptotic mechanism that ended in the complete denudation of the zona pellucida covering the early embryo. The presence of CC cells around the maturing oocyte and fertilized egg could have important functions related to the microenvironmental requirements of ovum maturation as well as facilitating activities related to fertilization.
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PMID:Ultrastructural features of bovine cumulus-corona cells surrounding oocytes, zygotes and early embryos. 1035 83

Morphological studies to localize mast cells in the wall of the convoluted and straight parts of the proximal tubules of the domestic swine kidney were performed. Kidney perfusion was carried out in 8-month-old pigs and semi-thin and ultrathin sections were prepared after a routine treatment. A light microscopic study showed that mast cells were not frequently found. Most were localized in the wall of the proximal convoluted tubule, while in the proximal straight tubule wall they were fewer in number. Most of the mast cells were oval in shape, their size being typical for this species, and the granules were reddish in colour. Three types of granule containing an evenly distributed granular-fibrous substance were found by TEM examination: the first type had a single electron-optically dense belt under the membrane; the second showed optically empty spaces between the substance and the cell membrane; the granules from the third type had two parallel dense belts below the granular membrane and were the smallest in size. Some of the granules of the first type were connected with the granular endoplasmic reticulum. A very narrow intercellular area and single desmosome-like junctions were found between the mast cells and the epithelial cells. Protrusions of plasmalemma and granules outside the cells were not established. On the basis of these results and data from the scientific literature, a comparative analysis was carried out. This showed certain differences between the results obtained and previous findings on the morphology of domestic swine mast cells and granules.
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PMID:Morphological study of mast cell localization in the wall of the proximal tubule in the domestic swine kidney. 1038 1

The present paper describes the morphological alterations of the epithelial layer of the uterine tubes of rats submitted to experimental chronic alcoholism using anatomical, histological, ultrastructural and morphometric methods. Sixty adult rats (Rattus norvegicus albinus) at the same age (3 months) and with a mean body weight of 228 g were divided into two groups. The control group received solid diet (Purina rat chow) and tap water ad libitum. The alcoholic group received the same solid diet and was allowed to drink only sugar cane brandy dissolved in 30 degrees Gay Lussac (v/v). After periods of 90, 180 and 270 days of treatment animals at normal estrus were anaesthetised with ethyl ether, weighed and sacrificed. Subsequently, the uterine tubes were dissected, weighed and prepared for TEM and SEM methods. The final mean body weights were similar in the control and alcoholic groups. The morphometric analysis showed no difference between control and alcoholic epithelial height. The alcoholic animals showed ultrastructural alterations: intense lipid droplet and lysosomes accumulation, dilated rough endoplasmic reticulum cisternae and vacuolization in both periods of treatment. It was concluded that alcohol acts as a toxin on the epithelial layer of the uterine tubes of rats.
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PMID:Ultrastructural changes on the epithelial cells of uterine tubes of Wistar rats after chronic ethanol ingestion. 1045 13

Calf lungs were fixed with glutaraldehyde and examined by scanning (SEM) and transmission (TEM) electron microscopy to compare the ultrastructure of Clara cells in terminal bronchioles of neonatal calves and older cattle. In the neonatal calf, SEM revealed numerous smooth-surfaced Clara cells protruding above a similar number of ciliated cells, whereas in older animals the surface of Clara cells was lobulated. Thin sections examined by TEM revealed numerous cuboidal to columnar Clara cells with indented nuclei and a pale cytoplasm filled with faintly granular glycogen in the neonatal calf. Some cells were characterized by apical dense and/or pale membrane-bound granules or secretory droplets. Many cells had an apical tubular network of cisternae that were partly smooth and partly decorated with ribosomes. Ultrastructural comparison of Clara cells in a 2-day-old calf with those of 14- and 19-day-old, 4- and 5. 5-month-old, and 3.5-year-old cattle revealed a striking reduction in the amount of glycogen per cell after 14 days. The number of cells with apical granules was small at all ages, and the density of the secretory granules varied greatly in different cells. A variable amount of smooth endoplasmic reticulum (SER) was present but was less prominent than cisternae of ribosomal endoplasmic reticulum (RER). In older cattle, the limited amount of SER compared to the RER and secretory granules suggests that bovine Clara cells are more likely to be secretory than detoxifying.
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PMID:Comparative ultrastructure of Clara cells in neonatal and older cattle. 1076 Oct 52


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