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At least 1,171 records · Page 65Linked to original sources
PubMed1987

The timing of granule cell differentiation and mossy fiber morphogenesis in the opossum.

The timing of developmental events may be important for the orderly formation of neuronal interconnections. In the present study, the timing of granule cell migration is compared with the arrival and maturation of mossy fiber projections. The opossum was chosen as the experimental animal because its protracted postnatal development enables the examination of developmental sequences not as easily recognized in other more commonly used mammalian species. It is shown that all areas that project to the cerebellum as mossy fibers in the adult opossum do so by postnatal day (PD) 30. Their major target, the granule cells begin inward migration from the external germinal layer (EGL) prior to PD 30, but do not form a distinct internal granular layer (IGL) until PD 35. Migrating granule cells penetrate into the IGL deep to granule cells that have begun dendritic differentiation. By PD 50, Golgi impregnations reveal that many granule cells have numerous immature processes, somal spines and dendritic growth cones. After this age these structures are rare and the vast majority of granule cells exhibit short dendrites with digiform endings. Dendritic differentiation subsequent to PD 54 involves an increase in the length of the shaft and the further maturation of terminal digits. Also from Golgi material, immature mossy fiber endings can be identified in the IGL by PD 35 and exhibit mature characteristics at PD 73. Thus, the formation and maturation of granule cell dendrites and their afferents (mossy fibers) occur over an extended period of time (PD 35-73). Moreover, granule cells exhibit a sequence of development similar to that of Purkinje cells: early arrival of their primary afferent projections in the cerebellar anlage; a period of exuberant dendritic growth; and a protracted and overlapping period for dendritic and synaptic maturation.

Animals↗
PubMed1981

Interferometric studies of endothelial cells in primary culture.

A population of endothelial cells grown from Xenopus laevis tadpole hearts was investigated by microinterferometry. The resulting interferograms were evaluated by an automatic image analyzer. The mean values of dry mass were 778 +/- 340 pg (10(-15) g) for whole cells, 648 +/- 309 pg for cytoplasm, 116 +/- 45 pg for nuclei, and 19 +/- 10 pg for nucleoli. Two subpopulations of cells were identified, an actively growing one and a less active one. The density (dry mass per microm2) of the nuclei and nucleoli of less active cells was greater than that of the nuclei and nucleoli of actively growing cells. In addition, the inactive cells were always large and possessed a considerable amount of cytoplasm. The entrance of cells into S-phase could not be detected by microinterferometry; and no differences were apparent between cells possessing one nucleolus and those containing two nucleoli. The values obtained in these amphibian cells were compared with those derived from mammalian cells.

Animals↗
PubMed1979

Primary culture of mammalian nephron epithelia: requirements for cell outgrowth and proliferation from defined explanted nephron segments.

Nephron segments were dissected from fetal or from early postnatal rabbit kidneys (n = 86) and explanted individually into primary tissue culture. Outgrowth of epithelioid cells and proliferation in monolayers from the collecting tubule and the thick ascending limb of Henle's loop occurred regularly if a special substratum and matrix were used. Media were either supplemented with non-proteins (defined media) or with embryo extract and fetal sera (undefined media). Outgrowth and monolayer spreading were recorded by Differential Interference Contrast Microscopy. Monolayer cells resemble those seen with the same recording technique during tubule in vitro perfusion. Undefined media were essential for growth of convoluted tubule segments from embryonic Nephron Anlagen and outgrowth of cells from proximal straight tubules, in contrast to the distal nephron segments. The specific functional and morphological properties of cells derived from primary culture of nephron segments are under study.

Animals↗
PubMed1979

Protein content, dry mass and chemical composition of individual mast cells related to body growth.

Recently developed quantitative microscopical techniques were used to study relations between body growth and protein content as well as dry mass of individual mast cells. Since previous studies had shown an age-related increase of mast cell content of 5-hydroxytryptamine (5-HT) and heparin, these mast cell components were also included in the present study. The cells were obtained from the peritoneal cavity of rats aged 44--269 days (body weights 189--610 g). All studied mast cell parameters showed an increase that was related to the growth of the animals. The dry mass increased 60%, protein 50%, heparin 50% but 5-HT increased as much as 260% during the studied growth period. There was a mutual and linear correlation between all studied mast cell parameters. Population studies, based on large scale measurements of individual mast cells from young and adult rats, were made. These studies showed that histograms of 5-HT content, protein content and dry mass of individual mast cells were skewed with a tail towards higher values and approximately lognormal. On the other hand, the frequency distribution of heparin content of individual mast cells was approximately normal.

Animals↗
PubMed1976

[Hereditary neuropathic Portuguese type of amyloidosis (author's transl)].

Report of a 35 year old male with hereditary neuropathic amyloidosis of the portuguese type, the second known case in Germany. There are extensive nodular Congo red positive amyloid deposits in the endoneurium of the peripheral nerves which lead to displacement, compression atrophy and interruption of the endoneural fascicles. The amyloid fibril structure is specially noted by interference contrast microscopy. It can also be documented in unstained microscopic sections. Further extensive nodular deposits are present in the mesangium of the glomerula. The remaining organs show preponderantly affected vessel walls and collagen fibres.

Adult↗
PubMed1987

In situ hybridization to detect Epstein-Barr virus DNA in oral tissues of HIV-infected patients.

Thirty biopsies of oral mucosal lesions and normal oral mucosa were obtained from 26 HIV-seropositive individuals and studied for virus infections with Epstein-Barr virus-specific DNA probes (EBV). In situ DNA hybridization was carried out on frozen and formalin-fixed, paraffin-embedded tissues. Specifically bound biotinylated virus probes were detected with the streptavidin-gold-silver technique and visualized by standard and interference reflection microscopy. In 9/30 biopsies, EBV DNA was clearly demonstrated in the upper two thirds of oral epithelia. This finding corresponded to peculiar cytopathic effects including ground glass nuclei, basophilic nuclear inclusions, and ballooning of the cytoplasm, which were concentrated in the upper two or three layers of the stratum spinosum. Cytopathic effects together with the demonstration of EBV DNA were demonstrated in seven cases of tongue mucosa, and two cases derived from the gingiva. When comparing clinical and pathological findings with DNA detection rates, we saw 5/9 hairy leukoplakias associated with EBV infections. Four positive cases (two samples from the tongue, two gingival specimens) had not been regarded as hairy leukoplakia clinically. EBV infection of the oral epithelium occurred in male homosexuals (7 cases) and in male/female intravenous drug abusers (2 cases). Among the nine EBV-positive cases, 2 patients were asymptomatic, 4 patients were grouped into the ARC-, and 3 individuals into the AIDS-category. We conclude that HIV-seropositive patients are particularly prone to develop productive EBV infections in oral epithelia. This infection most frequently appears at the lateral border of the tongue, but may also occur at other sites of the oral cavity, and may already exist in a preclinical stage prior to the development of oral white lesions (hairy leukoplakia).

AIDS-Related Complex↗
PubMed1985

Fractionation of Plasmodium chabaudi-infected erythrocytes into parasites and ghosts.

We have developed a new procedure for subfractionation of Plasmodium chabaudi-infected erythrocytes into parasites and ghosts. Trophozoite-infected erythrocytes enriched over a percoll-step (:1.10 g/cm3) are subjected to a glycerol-enhanced osmotic shock. This induces the release of parasites and the emergence of erythrocyte ghosts, which can be separated on a continuous percoll gradient (:1.02----1.10 g/cm3). The parasites are intact in terms of ultrastructure and incorporation of 14C-isoleucine. The erythrocyte ghosts are purified over a two-step percoll gradient (:1.01-1.02 g/cm3). Our method recovers about 40%-50% of the initial ghosts and 70%-95% of the initially freed parasites.

Animals↗