Live-Borns from XX but Not XY Oocytes: DISCUSSION(2)

Live-Borns from XX Oocytes

After mating with normal males, all XX XY chimeric females produced progeny exclusively derived from XX oocytes irrespective of the degree of XY contribution in body formation. Therefore, the fertility of XX oocytes was not abolished by the presence of XY somatic cells. We have previously reported several abnormal aspects of the B6.YTIR ovary during development, for example, transcription of the Sry gene in the ovarian primordium, postnatal development of abnormal endocrine features, and absence of regular estrous cyclicity at puberty. Since all XX XY chimeric females turned out to be fertile, the abnormalities that we have observed in the somatic components of the B6.YTIR female appear to be either not critical for fertility, caused only locally by the XY oocyte, or overcome by the presence of a small number of XX cells. birth control pills

Our conclusion would be invalid if XY cells were somehow excluded from the formation of ovaries despite the presence of XY cells in other parts of the body. However, we confirmed the presence of XY somatic cells in chimeric ovaries by in situ hybridization using a Y-specific DNA probe. Furthermore, the overall proportion of XY cells in the chimeric ovary corresponded to the proportion of XY cells determined by the DNA contents in the tail and kidney. Therefore, the XY contributions in the kidney, which shares the embryonic origin with the gonad, should indicate the varying degrees of chimerism in the ovaries examined in the present study. We could not determine the exact proportion of XY cells in the chimeric ovary that was subjected to morphological studies. However, even if it could be determined, the percentage of XY cells in the chimeric ovary after mating and pregnancy may be found to differ from the proportion at the time of ovulation and, therefore, may not provide any better information than that obtained from the kidney. It is currently impossible to correlate the fate of each oocyte and the composition of the follicle that encompassed the oocyte.

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