Female reproductive function has laid the foundation during the fetal period.
All egg cells in its life are multiplied and formed during the fetal stage; however, the egg cells at this time are immature and are called oocytes. Each oocyte is surrounded by a layer of primitive follicle cells, called granulosa cells, which together form the primitive follicle, the primordial follicle. These primordial follicles continue to grow and develop in batches from the fetal period to a woman\’s life, but most of them decline, atrophy, and die soon after they begin to develop. Only after the puberty period, some of them begin to grow and develop. The basal follicles can develop and mature.
During the childbearing years, generally speaking, only one follicle matures during each menstrual cycle. Although many follicles may be developing at the same time, most of them will wither and die before they mature. Under the regulation of hormones secreted by the hypothalamus and pituitary gland in the brain, one of the follicles continues to develop. At this time, the structure of the follicle becomes more and more complex. The oocyte in the center of the follicle gradually grows, and some cells around the follicle also differentiate and form theca cells. While follicles are developing, theca cells and granulosa cells work together to secrete estrogen to maintain the growth of the endometrium. A cavity gradually forms between the granulosa cells, which is filled with fluid, called follicular fluid. The cells surrounding the oocyte also secrete a substance called mucopolysaccharide, which forms a circle around the oocyte, called the zona pellucida. The oocyte develops and matures under the strict protection of the zona pellucida, follicular fluid and countless surrounding cells.
Mature follicles not only become larger in size and have more follicular fluid, but also the entire follicle gradually moves toward the surface of the ovary. At this time, the diameter of the follicle can reach 16 to 20 mm, which is called a mature follicle. At this time, the mature follicles, under the regulation of hormones, are about to enter the next stage – the ovulation process.
This article is provided by Baidu Reading and is excerpted from \”The Clear \”Conception\” Plan\” Author: Sun Jianqiu and Xie Yingbiao