On the structure of mammalian chromosomes during spermatogenesis and after radiation with special reference to cores

Abstract

The material used in this study was obtained from testes of C₅₇ black mice showing pathobiosis after 1000 r local acute X-rays, from control mice, and from biospy material of an oligospermic human male. Spermatocytes of the mouse survive 1000 r, and the timing and prophasic structure of meiotic chromosomes is not changed. In first meiotic metaphase the pathobiotic material shows kinetochores with more contrast than the control: the kinetochore regions are larger and the microfibrillar bundles of the chromosome body are more plainly defined (5). From such material the structure of the mouse chromosome can now be described with certainty. These meiotic bivalents of the mouse under low power electron microscopy correspond to the light microscope images published in the 30s for Trillium and Tradescantia (3).

This work was performed under the auspices of the US-Atomic Energy Commission.