Bioscientifica Proceedings

In mammals, testicular differentiation is initiated by SRY (the sex-determining region of the Y chromosome) gene expression in Sertoli cell precursors, followed by upregulation of the SOX9 gene (SRY-related HMG box gene 9). Subsequently, differentiated testis produces two hormones that induce sexual differentiation of the internal and external genital tract. Knowledge of the molecular mechanisms involved in gonadal differentiation has increased greatly over the past deca...

limiting factor to realizing the full potential of many of the new reproductive techniques is the lack of ahundant numbers of fertilizable oocytes. This problem could he addressed by using the large source of oocytes available from preantral and primordial follicles by developing systems for in vitro growth. In vitro systems that use early growing follicles as a source of oocytes have been developed for laboratory species and these have been successful ...

In this review the concept that the origins of embryonic failure occur during oocyte development is explored. The four factors that determine oocyte viability, namely a normal growth phase, adequate follicle cell support during maturation, the completion of intracellular reprogramming before fertilization and the functioning of oocyte surveillance mechanisms, form the four sections of this review. The viability of pig oocytes at the end of the growth phase is compromised...

Fertilization of the egg, or oocyte, initiates the entire developmental process, but while the mechanism by which the spermatozoa triggers the oocyte to resume meiosis has been studied extensively, conclusions about this process are still elusive. Some workers have suggested that a molecule on the surface of the spermatozoon may interact with a receptor on the plasma membrane of the oocyte, thereby triggering the oocyte to resume meiosis. Other workers have focused on a ...