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Biomedical subjects

U Welsch

Publications and source records attributed to U Welsch.

At least 127 records · Page 7Linked to original sources
PubMed1976

Temperature dependent changes in the thyroid gland of Mertensiella caucasica (Urodela, Amphibia).

The influence of temperature on the thyroid gland of the Caucasian salamander, Mertensiella caucasica has been studied (1) with the light- and electron microscopes, (2) with enzyme histochemical and quantitative methods. Animals which had been kept for years at 16 degrees C were exposed for 48 hrs to 4 degrees C or 27 degrees C. At 4 degrees C the follicular epithelium consisted of cuboidal cells with well-developed rough ER, occasional distended cisternae of the rough endoplasmic reticulum (ER) filling most of the cytoplasm, a relatively small Golgi apparatus and numerous round or oval shaped lysosomes. In animals kept at 27 degrees C the follicular wall was composed of markedly taller epithelial cells, the apices of which bulged into the follicular lumen. Compared to the animals at 4 degrees C, there appeared to be a decrease in the rough ER. The Golgi apparatus did not exhibit clear differences. The lysosomes increased in number and showed various shapes among which elongated ones with pointed ends were particularly striking. In the apical cytoplasm colloid droplets appeared indicating hormone release. The apical microvilli increased in number. The measurements of total T4 have shown that the hormone level in animals kept at 27 degrees C was about twice as high as in animals kept at 4 degrees C.

Animals↗
PubMed1976

[Electron microscopic studies of the gill epithelium of the amphibian teleost Periophthalmus vulgaris].

The gill epithelium of the airdwelling fish Periophthalmus vulgaris has been studied with the electron microscope. The following celltypes can be distinguished: flat covering epithelial cells, chloride cells, mucous cells, basal cells, various leucocytes as well as a specific granule containing cell which is possibly an epithelial cell. The covering epithelial cells exhibit a relatively smooth apical surface and contain in their apical half densely packed microfilaments, pinocytotic vesicles are rare. These characteristics are not to be found in water dwelling fish and possibly represent adaptations to the air containing surroundings. In the chloride cells are numerous, especially in the basal halves of the secondary lamellae. The distal parts of the secondary lamellae the barrier for the respiratory gases measures about 0,9 micrometer. The basal cells are ribosome rich replacement cells. Two types of mucous cells occur. Individual intraepithelial nerve fibres have been observed.

Animals↗
PubMed1975

Observations on the fine structure, enzyme histochemistry, and innervation of parathyroid gland and ultimobranchial body of Chthonerpeton indistinctum (Gymnophiona, Amphibia).

Fine structural and enzyme histochemical observations on ultimobranchial body and parathyroid gland of the caecilian Chthonerpeton are presented. The cell clusters and follicles of the ultimobranchial body consist mainly of granulated cells which are termed C-cells and obviously belong to the APUD cell series. In the larger follicles additional possibly exhausted degranulated cells and replacement cells occur. A rich supply of nerve fibres has been found in this gland. Frequently nerve terminals were observed to come into synaptic contact with the C-cells. Two categories of nerve fibres occur: a) fibres containing large polymorphic electron dense granules (probably purinergic fibres), b) fibres containing small electron transparent vesicles and a few electron dense granules (probably cholinergic fibres). The parathyroid gland consists of elongated cells (one cell type) poor in organelles and often containing fields of glycogen and lipid droplets. The cells are further characterized by fair amounts of lysosomal enzymes; they are interconnected by maculae adhaerentes and occludentes. No nerves and blood vessels have been found in the parathyroid gland of Chthonerpeton.

Acid Phosphatase↗