The Growth and Development of the Gonad in Japanese House Shrew (<I>Suncus murinus riukiuanus</I>)
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概要
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Data on the postnatal gonadal development were obtained from 196 litters of <I>Suncus murinus riukiuanus</I> born in captivity.<BR>The male: In the first days of life the seminiferous tubules contain scatterd spermatogonia and Sertoli cells, and interstitial tissue (identified as Leydig cells) present. The testes length and diameter of seminiferous tubules grow gradually after birth. Mature spermatozoa are found in the testes and epididymides at 5 weeks.<BR>The female: In the newborn female the ovary contains many primordial follicles and a few primary follicles. The diameter of follicle grows rapidly after 11 days. At 3 weeks large follicles with diameters ranging from 270-375 μm appear in the ovary. No larger follicle diameters are found in the adult female prior to copulation.<BR>According to the histological point of view, sexual maturity is attained by the age of 5 and 3 weeks, male and female respectively.<BR>Finally, the author tried to compare the process of development in Soricidae to those in Primates. So far studied, sexual maturity is attained by the age of 2 months in Soricidae. On the other hand, it takes 7 months or more in Primates. This delayed puberty in Primates seemed to depend on the lengthening of rest period in development.