Search results
Results from the WOW.Com Content Network
An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female germ cells produce a primordial germ cell (PGC), which then undergoes mitosis, forming oogonia. During oogenesis, the oogonia become primary oocytes. An oocyte is a form of genetic material that can be collected for cryoconservation.
The primary oocyte is defined by its process of ootidogenesis, which is meiosis. [2] It has duplicated its DNA, so that each chromosome has two chromatids, i.e. 92 chromatids all in all (4C). When meiosis I is completed, one secondary oocyte and one polar body is created. Primary oocytes have been created in late fetal life.
In fact, a primary oocyte is, by its biological definition, a cell whose primary function is to divide by the process of meiosis. [16] However, although this process begins at prenatal age, it stops at prophase I. In late fetal life, all oocytes, still primary oocytes, have halted at this stage of development, called the dictyate.
In contrast with males, each of the original diploid germ cells or primary oocytes will form only one mature ovum, and three polar bodies which are not capable of fertilization. It has long been understood that in females, unlike males, all the primary oocytes ever found in a female will be created prior to birth, and that the final stages of ...
Unlike sperm production, oocyte production is not continuous. These primary oocytes begin meiosis but pause in diplotene of meiosis I while in the embryo. All of the oogonia and many primary oocytes die before birth. After puberty in primates, small groups of oocytes and follicles prepare for ovulation by advancing to metaphase II.
Once the primary oocytes stop dividing the cells enter a prolonged 'resting phase'. This 'resting phase' or dictyate stage can last anywhere up to fifty years in the human. For several primary oocytes that complete meiosis I each month, only one or a few functional oocyte, the dominant follicles, completes maturation and undergoes ovulation ...
In biology, folliculogenesis is the maturation of the ovarian follicle, a densely packed shell of somatic cells that contains an immature oocyte. Folliculogenesis describes the progression of a number of small primordial follicles into large preovulatory follicles that occurs in part during the menstrual cycle .
In the ovaries, the developing egg cells (or oocytes) mature in the fluid-filled follicles. Typically, only one oocyte develops at a time, but others can also mature simultaneously. Follicles are composed of different types and number of cells according to the stage of their maturation, and their size is indicative of the stage of oocyte ...