New observations on mammalian male meiosis

摘要

Evidence for the existence of lampbrush pachytene chromosomes and of a diffuse stage between pachytene and diplotene is presented in mouse and monkey spermatocyte meiosis with the help of a special staining technique. Attention is payed to the existence of interchromosomal connections. It is shown, that the hypotonic treatment, commonly used to get better chromosome spreading in mammals, primarily facilitates rupture of the interchromosomal connections and release of the metaphase chromosomes from each other. Different sensitivity of mitotic and meiotic divisions is exemplified by data published on the effect of progesterone on meiosis and mitosis, respectively. The necessity of testing the effects of mutagens on meiosis is stressed.