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Biomedical subjects

N Egami

Publications and source records attributed to N Egami.

At least 37 records · Page 2Linked to original sources
PubMed1982

Age related changes in morphology of the thymus of the fish, Oryzias latipes.

The thymus of the teleost fish Oryzias latipes is a paired structure found at the dorsoposterior part of the gill chamber. In 3-month-old fish, the thymus shows a great development. The thymus displays atrophy during aging, and the thymus involution continues until 5 years of age. Male thymus shows heavier involution than female thymus of the same age. Emigration of thymus cells takes place at all ages but increases with age.

Aging↗
PubMed1980

Hertwig effect caused by UV-irradiation of sperm of Oryzias latipes (teleost) and its photoreactivation.

When sperm of the fish Oryzias latipes were irradiated with ultraviolet light and allowed to fertilize normal eggs, the so-called "Hertwig effect" was observed, with a dose-dependent decrease in survival rate at low doses (0-27 J . m-2) but a better survival rate at higher dose ranges. Illumination with visible light after fertilization (10-70 min after insemination) showed the existence of photoreactivation (PR), demonstrating that pyrimidine dimers are a lesion in sperm DNA that is mainly responsible for the UV-caused Hertwig effect. Genetic analysis, in which sperm from a wild-type of this fish was used, showed that, after UV-irradiation at the high dose range, male nuclei did not participate in embryonic development (a gynogenetic haploid condition). Embryos having only a maternal set of chromosomes could develop no further than stage 27. Only the visible light during the early part (until around 20-30 min after insemination, at 25 degrees C) of the single-cell stage was effective for PR; illumination thereafter was not.

Animals↗