Fourth World Conference on Early Pregnancy CONTINUUM BETWEEN IMPLANTATION AND PERINATAL EVENTS

Expression Of Fas In The Oocyte And In The Embryo Of Mouse

Nandedkar T.D., Dharma S.J. and Kelkar R.L

Department of Cell Biology, Institute for Research in Reproduction, Jehangir Merwanji Street, Parel, Mumbai 400 012, INDIA

Presentation

Programmed cell death (PCD) or apoptosis is a natural phenomenon observed in most of the somatic cells as well as in gametes. In the ovarian oocyte it is prominent as out of one million oocytes present in the ovary of women, only 450 ovulate during the reproductive life span and rest of 99.9% oocytes degenerate. Following ovulation, only if the ovum is fertilized pregnancy will occur. Moreover, all the fertilized ova do not implant. Thus at every stage oocytes may degenerate either in the atretic follicle, in the oviduct after ovulation but no fertilization or in the uterus if the embryo is unable to implant. In the present study, therefore, attempts have been made to study involvement of a TNFa receptor family gene namely Fas in the oocyte and in the fertilized embryo and blastocyst the major stages of development, using immunohistochemical localization and in situ hybridization techniques. Fas was expressed in follicle cells but not in the oocyte of atretic follicles of mouse ovary. Expression of Fas in the fertilized oocyte collected from oviduct on D1 of pregnancy was noted. On D4 of pregnancy the blastocyst flushed from the uterus also expressed Fas in the inner cell mass. These results indicate that Fas may play an important role after fertilization and its expression may be essential prior to implantation in normal blastocyst as well.

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