[Important roles of oocytes, follicles and corpora lutea in ovarian teratocarcino-genesis in mice].

In strains LT/Sv and LTXBJ mice, susceptible to spontaneous ovarian teratocarcinogenesis, ovarian teratomas are derived from parthenogenetically activated ovarian eggs. The follicles containing the parthenotes are the abnormal ones in which granulosa cells show histochemically high activity of beta-glucuronidase (beta-G). To investigate whether ovarian teratocarcinogenesis depends on the genetic nature of eggs themselves or the microenvironment in the abnormal follicles, we used chimeras derived from aggregates of eight-cell embryos of strains LTXBJ or (LTxLTXBJ) F1 and of normal nonsusceptible strain C3H/HeJ which shows low activity of beta-G genetically. The original strain of teratomas and follicles in chimeras were histochemically determined by activity of beta-G as a marker. The results showed that both teratomas and the follicles containing parthenotes originate from the susceptible strains. Then, we examined for presence of activated oocytes, teratomas and corpora lutea in LT ovaries untreated or treated with PMSG-HCG implantation. These results showed that parthenogenetic blastocysts closely adhere to the follicle tissue as if a kind of and develop to post implantation stages in the ovaries in which corpora lutea were formed near the parthenotes. In conclusion, it was suggested that ovarian parthenogenesis in mice occurs most frequently when eggs with genetically susceptible nature, were exposed to the microenvironment produced by the abnormal follicles, and these parthenotes adhere to the ovarian tissues and differentiate three germ layers by some roles of corpora lutea and undergo teratocarcinogenesis.