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.
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.
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.
At puberty, one primary oocyte will continue meiosis each menstrual cycle. Because there is an absence of regenerating germ cells and oogonia in the human, the number of primary oocytes dwindles after each menstrual cycle until menopause , when the female no longer has a population of primary oocytes.
Ovulation is the regular release of one oocyte from the ovary into the reproductive tract and is preceded by follicular growth. A few follicle cells are stimulated to grow but only one oocyte is ovulated. A primordial follicle consists of an epithelial layer of follicular granulosa cells enclosing an oocyte.
During oogenesis, the oogonia become primary oocytes. Oocytes (immature ova) residing in the primordial follicle of the ovary are in a non-growing prophase arrested state, but have the capacity to undergo highly efficient homologous recombinational repair of DNA damages including double-strand breaks. [1]
This is known as the primary oocyte. Human females are born with all the primary oocytes they will ever have. [10] Starting at puberty the process of meiosis can complete resulting in the secondary oocyte and the first polar body. [10] The secondary oocyte can later be fertilized with the male sperm.
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.