THE DEVELOPMENT OF THE MOUSE OVARY FROM BIRTH TO MATURITY

ABSTRACT Changes occur in the infant ovary which develop the structurally simple organ at birth to a highly complex one in the maturing animal. The ovary in the immature mouse is not a dormant organ but one that is characterized by a continuous growth and development and a concurrent continuous degeneration of oocytes and follicles. The stroma cells which are present in the ovary at birth are apparently a pool of cells with multiple potentialities, which contribute to the development of the earliest granulosa and theca cells. The interfollicular stroma of the juvenile ovary, however, originates from collapsing and contracting follicles. The quantitative changes in the oocyte and follicle population during the immature period lead to a marked reduction in the total number of oocytes and a simultaneous numerical increase in follicles at different stages of development. Factors influencing oocyte atresia and follicle development in the immature mouse are discussed.