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A secondary follicle sectioned through the nucleus of an oocyte is at the upper left, and earlier stage follicles are at the lower right. The tissue was stained with the dyes hematoxylin and eosin. The outer layer is the ovarian cortex, consisting of ovarian follicles and stroma in between them.
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.
Death from ovarian cancer increased globally between 1990 and 2017 by 84.2%. [23] Ovarian cancer is the second-most common gynecologic cancer in the United States. It causes more deaths than any other cancer of the female reproductive system. [24] Among women it ranks fifth in cancer-related deaths. [25] The typical age of diagnosis is 63. [2]
The resulting zygote then gives rise to an embryo, which will grow into a new diploid individual, known as a sporophyte. In seed plants, a structure called the ovule contains the female gametophyte. The gametophyte produces an egg cell. After fertilization, the ovule develops into a seed containing the embryo. [14]
Oocytes are then able to mature within the follicle through meiosis. In humans with ovaries, this process occurs continuously, as they are born with a finite number of follicles (between 500,000-1,000,000 follicles), and about 99% of follicles undergo atresia. [4] Only one follicle will be mature enough to release an egg and may be fertilized. [5]
Oocyte maturation abnormalities (OMAS) are repeatedly experienced in a small percentage of infertile women. [4] These are problems with the maturation of oocytes; the step in oocyte development that occurs just before ovulation and successive fertilisation. [5] Oocytes must mature in order to reach reproductive potential. [4]
An oocyte (/ ˈ oʊ ə s aɪ t /, oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. 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 ...
If no fertilization occurs, the oocyte will degenerate between 12 and 24 hours after ovulation. [18] Approximately 1–2% of ovulations release more than one oocyte. This tendency increases with maternal age. Fertilization of two different oocytes by two different spermatozoa results in fraternal twins. [10]