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Updated: May 22, 2025
Many investigators have found that the Roentgen rays destroy the spermatic cells of the testis in Mammals, leaving the cells of Sertoli, the interstitial tissue, nerves, and vessels uninjured. G. d. Roy. It seems possible, although no such suggestion has been made, that the interstitial cells might either normally or exceptionally give rise to ova and spermatocytes.
Many physiologists in recent years have maintained that the testicular hormone is not derived from the male germ-cells or spermatocytes, but from certain cells between the spermatic tubuli which are known as interstitial cells, or collectively as the interstitial gland. They state that the interstitial cells appear in the male embryo before the gametocytes present distinctive sex-characters.
Spermatogenesis is not the only source of the testicular hormone: changes in the secretory activity of the interstitial cells or spermatocytes are sufficient to account for periodic development of somatic sex-characters, and the same reasoning applies to the antlers of stags. The milk glands in Mammals constitute one of the most remarkable of secondary sexual characters.
Then when the heterotypic division takes place and the number of chromosomes is halved, we shall have two spermatocytes with N-1 chromosomes from one of the first spermatocytes and one with N and one with N-1 from the other. Thus there will be three spermatozoa with N-1 chromosomes and one with N chromosomes, whereas we are supposed to find equal numbers with N and N-1 chromosomes.
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