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The histones present in the rat testis during early testicular development have been analyzed on acid-urea polyacrylamide gels and amounts of the individual histones quantified at 5 day intervals from 5 through 35 days of age. Three new histones, F1M, F2a2M and F2bM as first reported by Branson et al. (1975) are shown to originate from the primary spermatocyte and displace somatic histones Fl, F2a2 and F2b, respectively. Small bands of modified histones which are derived from the mitotically active supporting (immature Sertoli cells) cells are present at 5 and 10 days of age, but disappear by 20 days of age, a time coincident with cessation of replication of the Sertoli cells. Testis preparations having no germinal epithelium (SCE-testis), have only somatic type histones, thus providing further support for the germ cell origin of the FM histones. Finally, hyperchromicity profiles of rat testis chromatins reveal that chromatin preparations containing the new meiotic histones are thermally more stable. These data suggest a tighter binding of the new histones to the DNA of meiotic cells.
Mills et al. (Thu,) studied this question.