Figure 2.

The ovary anatomy, folliculogenesis, oogenesis, and encapsulate in vitro follicle growth (eIVFG). (A) The earliest stage of ovarian follicles are termed primordial follicles which remain quiescent to represent ovarian reserve. After birth, the primordial follicles are activated and grow to the primary, secondary, and antral stages for ovulation until menopause, which is termed folliculogenesis. In parallel to folliculogenesis, the oocytes increase in size and store mRNAs and proteins to gain meiotic and developmental competence, which is termed oogenesis. The ovulation is characterized by the rupture of antral follicles and release of oocytes into the fallopian tube. During ovulation, the oocytes resume meiosis and progress to metaphase II (MII) stage. After ovulation, the remaining granulosa cells and theca cells differentiate into luteal cells, form corpus luteum (CL), and secrete progesterone. (B) The eIVFG maintains the 3D architecture of ovarian follicles and supports mouse follicle development from multilayered secondary stage to antral stage for maturation, ovulation, oocyte meiotic division, and luteinization.