Mother has the final say.
For young male offspring who suffer a dominant mother, a brother may be on the way to help bear the burden. And all because of follicular testosterone. A growing body of evidence suggests a maternal influence on sex determination: dominant human females conceive more sons. Grant et al., in an article on p. 812 of the May issue of Biology of Reproduction, find that the sex of bovine embryos positively correlates with pre-ovulatory follicular testosterone. How exposure of oocytes to follicular testosterone may influence the ability of a metaphase II egg to be preferentially inseminated by a Y-bearing sperm remains a mystery. What is known is that chronic stress elevates testosterone in females (but not males). So if you would like your next sibling to be a sister, dont aggravate your mother.
Sex of Bovine Embryos May Be Related to Mothers' Preovulatory Follicular Testosterone. V. J. Grant, R. J. Irwin, N.T. Standley, A. N. Shelling, and L. W. Chamley. Biol Reprod 2008; 78:812-815. Published online in BOR Papers-In-Press 9 January 2008; DOI 10.1095/biolreprod.107.066050
Kid? Or Mom?
Maternal cell microchimerism was first detected in karyotyped human male infants in the 1960s; however, little is known about this phenomenon. Now, on p. 883 of the May 2008 issue, Su et al. report results of a study designed to establish number of maternal cells present, effects of stage of gestation and preferential homing of maternal cells to fetal organs of mice. Such basic information is of interest because maternal cells are present in affected tissues of children with inflammatory myopathy, scleroderma, and neonatal lupus; however a cause and effect relationship has not been established. The authors found an average of 158 maternal cells per 100,000 neonatal cells in fetal mice, with preferential homing of these cells to fetal heart and lung, compared to liver and spleen (although other work
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