Biomedical subjects
Publications and source records attributed to M Zweyer.
Flagellar filaments traited with ferrotannic mixture and impregnated with ammoniacal silver solution, observed at microscope by reflected light, present a striking brightness and a neat aspect. We think that the constancy of the results obtained by this method, can facilitate in various experimental conditions, the study of bacterial flagella.
The histological and ultrastructural appearances of the inner ear vestibulum were studied after transtympanic administration of gentamicin in guinea-pigs. The animals were treated with a single transtympanic dose (0.2 cm3) of 4% gentamicin sulphate solution in the right ear; the left one was considered as control. After 7 days they were sacrificed and the vestibula of both inner ears were removed to be examined both by light and electron microscopy. In the treated inner ear damage was not always evident at light microscopical level, even if a case of complete disepithelialization of cristae ampullares was found. The examination by TEM revealed evident damage in the vestibular non-sensorial cells, such as severe cellular vacuolation, whereas sensorial elements presented heterochromatinic thickenings and cytoplasmic wrinkling, as compared to controls. The tunica fibrosa presented an irregular fibrillar plot, as well as that of the myelinic lamellae in the vestibular nerve fibres.
Recent studies have shown that protein kinase C (PKC) plays a pivotal role in many cellular functions, i.e. cell proliferation and differentiation, exocytosis, ion-exchange regulation, hormone and neurotransmitter release, programmed cell death. Up to now the tissue and organ distribution of PKC isoenzymes have been studied in various mammalian adults and it has been suggested that each of them could play a specific role in the regulation of various cellular functions. However, few works have been performed on the expression of the enzyme in actively proliferating and differentiating tissues, i.e. during embryonal and fetal developmental stages. In the present study we have performed an immunohistochemical analysis by using polyclonal antibodies in order to verify the distribution of nine PKC isoenzymes in the vertebral column of human fetuses in a key period (8th developmental week), when the most relevant chondrogenetic and osteogenetic processes occur. The detection of the various PKC isoenzymes and their different distribution in the vertebral bodies and in the intervertebral spaces lead to speculate that the appearance, localization and activation of PKC isoforms in chondrocytes might depend on the stage of chondrogenesis and suggest that cartilage and developing bone represent an appropriate cell system to understand the mechanism of signal transduction, which involves the enzyme.
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The presence of melatonin and other biogenic indoleamines in the Harderian gland has been proposed by various authors. In the present work we would have investigated which of the cytotypes of the mouse Harderian gland might be involved in melatonin turnover. For this aim we employed the osmium tetroxide-zinc iodide (ZIO) histochemical technique that has been proposed useful to identify indole monoamines. Harderian glands of male, female and pregnant female mice were studied by light and transmission electron microscopy (TEM). Secretory type B cells were selectively stained by the ZIO-mixture, much more in female than male; type A cells were much more numerous than type B ones and never ZIO-positive. Ultrastructural examinations showed that type B cells contain numerous granules in the whole cytoplasm, in the perinuclear cisterna and around the cytoplasmic vacuoles and vesicles. Myoepithelial cells were sometimes found weakly ZIO-positive. Endothelial cells of capillary blood vessels presented ZIO-precipitates in the cytoplasm, as well as in the perinuclear cisterna. These data may suggest an uptake of melatonin from the blood stream and an involvement of type B secretory cells in melatonin catabolic turnover, or a "in situ" melatonin biosynthesis and endocrine secretion by the same B cells. The higher ZIO-positivity of type B cells in female than male may be related also to the influence of sexual steroid hormones, that characterizes the porphyrin pigment amount involved in melatonin oxidation.
A study on the presence of corpuscular nerve endings in human gingival mucosa was performed using both light and transmission electron microscopic (TEM) techniques. Both round and oval lamellar corpuscles were detected by light microscopy. They were located either subepithelially, close to the basement membrane, or within the papillae, deeply invaginated into the overlying epithelium. TEM techniques showed convoluted structures with unmyelinated fibre arborizations leading to an afferent fibre supported by the so called lamellar cells. The presence of blood vessels, collagenous fibrils, desmosome-like junctions, cytoplasmic organelles, as well as the similarity with some previously described mechanoreceptors, suggested the role of such corpuscular nerve endings in transmitting a nervous impulse induced by mechanical stimulation. Other simpler structures were also observed and named "club-shaped" corpuscles: they could support the more complex ones in responding to the strengths and the movements directly influencing the gingival mucosa.