ABERRANT OVULATION–CONSEQUENCES ON FERTILITY AND EMBRYONIC DEVELOPMENT

Abstract

Experimental evidence and clinical observations which have accumulated suggest that the timing of ovulation in relation to preovulatory events is an important factor associated with infertility. These events affect both intra-uterine environment and the meiotic and biochemical processes in the preovulatory oocyte. The separate effects are difficult to define as any hormonal changes affecting the follicular oocyte are likely also to influence intra-uterine environment. Although a large volume of literature has accumulated on the subject of infertility, relatively little attention has been given to the role of the oocyte as a contributor to decreased fertility. Following alteration of the time of ovulation, infertility is often attributed to a hostile intra-uterine environment or to improper timing of insemination without considering the modifications that have occurred in the oocyte. Elucidation of the mechanism of rupture of the ovarian follicle is progressing rapidly (Rondell, 1970; Lostroh, 1971); the process of meiosis has been reviewed in detail in many species (Edwards, 1965Edwards, 1966; Mandl, 1963; Donahue, 1968; Schuetz, 1969); but the factors which produce the preovulatory resumption of meiosis are not fully understood. The consensus has been that it is due to the preovulatory surge of LH. However, maturation of oocytes from several species has occurred in vitro in the absence of hormones following mechanical rupture of follicles (Pincus and Enzmann, 1935; Edwards, 1966). Donahue and Stern (1968) found that either follicular cells in glucose medium or medium without cells in the presence of pyrovate or oxaloacetate would support maturation of mouse oocytes in