In mammalian development, the germ cells undergo sexual differentiation according to their gonadal environment, testis or ovary, which is determined by the presence or absence of the Y-linked Sry gene. Therefore, spermatogenesis and oogenesis take place in the presence of XY and XX sex chromosomes, respectively. When gonadal sex-reversal occurs, however, the germ cell sex becomes discordant with the chromosomal sex. Both XX males and XY females in humans are infertile while XY females are fertile in certain rodent species. In Mus musculus (house and laboratory mice), XY females show variable fertility dependent on the cause of sex-reversal and genetic background, providing tools for studying the role of sex chromosomes in oocyte fertility. Of particular interest is the B6.YTIR mouse, which develops into either a fertile XY male or infertile XY female carrying an identical intact Y chromosome. The objective of our studies is to understand the influence of sex chromosomes on the reproductive potential of oocytes. Our current studies are focused on (1) the association of gonadal somatic cell and germ cell sex differentiation in the B6.YTIR ovary and ovotestis, (2) the relationship between asynapsis of the single X chromosome and a greater loss of oocytes during the Meiotic Prophase I progression in XY and XO female mice, (3) the apoptotic pathway(s) involved in the elimination of oocytes with meiotic errors, and (4) mechanism of the second meiotic division defect in the oocytes from XY females.

Parinaz Kazemi, MSc
PhD student
parinaz.kazemi@mail.mcgill.ca

Xueqing Liu, PhD
Postdoc
xueqing.liu.ucsf@hotmail.com

Wataru Yamazaki, PhD
Postdoc
wataru.yamazaki@mail.mcgill.ca

Fatima El Mansouri, PhD
Research associate
fatima.ezzahra.el.mansouri@umontreal.ca