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Biomedical subjects

Y Nishimune

Publications and source records attributed to Y Nishimune.

155 records · Page 9Linked to original sources
PubMed1981

Testicular DNA synthesis in vivo: comparison between unilaterally cryptorchid testis and contralateral intact testis in mouse.

DNA synthetic activity was studied by autoradiography in unilaterally cryptorchid (abdominal) and contralateral intact(scrotal) testes in mice. Nongerm cells were inactive in DNA synthesis in both the cryptorchid testis and in the intact control. Labeling indices of undifferentiated type A spermatogonia did not show any differences, indicating that type A spermatogonia did not temperature sensitive in DNA synthesis in vivo.

Animals↗
PubMed1980

The effects of steel mutation on testicular germ cell differentiation.

The effects of artificial cryptorchidism and its surgical reversal on spermatogenesis were examined in germ cell mutant, S1/+ and wild type, +/+, mice. In cryptorchid testes no difference was found between S1/+ and +/+ mice in the number of undifferentiated type A spermatogonia. The activity of type A spermatogonia in mutant mice appeared normal as judged by its mitotic cell number and DNA synthesis. The surgical reversal of cryptorchidism resulted in regenerative differentiation of mature germ cells in both types of mice, but the pattern of cellular differentiation in the mutant testes was completely different from that of the wild type testes. At two steps of cellular differentiation, intermediate or type B spermatogonia and spermatid, the numbers of cells were much smaller in the S1/+ testes than those in the +/+ testes. The steel gene was therefore suggested to exert its effects on the differentiation of type A spermatogonia to intermediate or type B spermatogonia, on meiotic division and/or the survival rate of these cells, but not on the undifferentiated type A spermatogonia or stem cells.

Animals↗
PubMed1979

In-vitro differentiation of type A spermatogonia in mouse cryptorchid testis.

Cryptorchid testes from adult mice were incubated in calf serum-supplemented medium. There was an effective differentiation of adult type A spermatogonia up to the pachytene stage of meiotid division whcih resembled the process of spermatogenesis in vivo. In the absence of calf serum, type A spermatogonia did not differentiate at all. They differentiated when the serum was present for the first day, but was absent for the rest of cultivation. These results indicate that serum is necessary for only the early process of spermatogenesis from type A spermatogonia in vitro and not for the further processes of germ cell differentiation. Type A spermatogonia cultured in serum-free medium retained the ability to differentiate for at least 3 days.

Animals↗
PubMed1979

Local development of mast cells from bone marrow-derived precursors in the skin of mice.

A mechanism to control development of mast cells was investigated in mice. Although mast cells in the skin of normal C57BL/6 mice were still of host type 290 days after irradiation and injection of bone marrow cells from beige (Chediak-Higashi syndrome, C57BL/6 bgJ/bgJ) mice, donor-type mast cells with giant granules appeared after painting of methylcholanthrene on the dorsal skin. Since donor-type mast cells appeared only at the painted portion of the skin, with an increase in the labeling index of such donor-type mast cells with 3H-thymidine, proliferation and differentiation of bone marrow-derived precursors of mast cells seem to be controlled locally. Although the morphologic feature of marrow-derived precursors was not identified, the finding that all fibroblasts cultured from the methylcholanthrene-treated skin were of host type may exclude the possibility that fibroblasts are the precursors of mast cells.

Bone Marrow Cells↗
PubMed1978

Temperature sensitivity of DNA synthesis in mouse testicular germ cells in vitro.

The effect of temperature on testicular DNA synthesis in mice was studied in vitro. By using cultures of cryptorchid testis, DNA synthesis of differentiated germ cells, such as intermediate and type B spermatogonia and resting primary spermatocytes, was shown to be temperature-sensitive, while that of undifferentiated type A spermatogonia was not. DNA synthesis of non-germ cells was not temperature-sensitive. This temperature sensitivity of germ cells in DNA synthesis may be one cause of the thermal inhibition of germ cell differentiation.

Animals↗
PubMed1978

Testicular germ cell differentiation in vivo.

The effects of artificial cryptorchidism and surgical reversal on spermatogenesis were examined in mice. Only undifferentiated type A spermatogonia were present as germ cells in cryptorchid testes. The surgical reversal of cryptorchidism resulted in regenerative differentiation of mature germ cells as judged by testicular weight, histologic examination, and increase in the specific activity of lactate dehydrogenase-X. Leydig cell function was also examined by assessment of the weight of target tissues of androgen. They showed a unique change following the surgical reversal. Thirty days after surgical reversal, hyperfunction of the Leydig cells was observed, and the testes became normal after 60 days.

Animals↗
PubMedDate not supplied

Secretion of plasminogen activator in response to follicle-stimulating hormone in culture medium of human testicular cells from biopsy specimens.

Testicular cells from human biopsy specimens were cultured and plasminogen activator secreted into the medium was investigated. Follicle stimulating hormone stimulated plasminogen activator secretion. SDS-polyacrylamide gel electrophoresis followed by zymography showed that the molecular weight of plasminogen activator produced by human testicular cells is the same as that of human urokinase. Antigenicity was also found to be of the urokinase type but not of the tissue type.

Adult↗