An immature ovum is a cell that goes through the process of oogenesis to become an ovum. It can be an oogonium, an

oocyte An oocyte (, ), 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 femal ...

, or an

ootid An immature ovum is a cell that goes through the process of oogenesis to become an ovum. It can be an oogonium, an oocyte, or an ootid. An oocyte, in turn, can be either primary or secondary, depending on how far it has come in its process of me ...

. An oocyte, in turn, can be either primary or secondary, depending on how far it has come in its process of

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately r ...

Oogonium

Oogonia An oogonium (plural oogonia) is a small diploid cell which, upon maturation, forms a primordial follicle in a female fetus or the female (haploid or diploid) gametangium of certain thallophytes. In the mammalian fetus Oogonia are formed in lar ...

are the cells that turn into primary oocytes in oogenesis. They are diploid, i.e. Oogonia are created in early embryonic life. All have turned into primary oocytes at late fetal age.

Primary oocyte

The primary oocyte is defined by its process of

ootidogenesis Oogenesis, ovogenesis, or oögenesis is the differentiation of the ovum (egg cell) into a cell competent to further develop when fertilized. It is developed from the primary oocyte by maturation. Oogenesis is initiated in the embryonic stage. O ...

, which is meiosis. 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 A polar body is a small haploid cell that is formed at the same time as an egg cell during oogenesis, but generally does not have the ability to be fertilized. It is named from its polar position in the egg. When certain diploid cells in animals ...

is created. Primary oocytes have been created in late fetal life. This is the stage where immature ova spend most of their lifetime, more specifically in diplotene of prophase I of meiosis. The halt is called

dictyate The dictyate or dictyoteneMedical Physiology, Boron & Boulpaep, , Elsevier Saunders 2005. Updated edition. 1300 pages. is a prolonged resting phase in oogenesis. It occurs in the stage of meiotic prophase I in ootidogenesis. It starts late in fet ...

. Most degenerate by

atresia Atresia is a condition in which an orifice or passage in the body is (usually abnormally) closed or absent. Examples of atresia include: *Aural atresia, a congenital deformity where the ear canal is underdeveloped. * Biliary atresia, a condition i ...

, but a few go through

ovulation Ovulation is the release of eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilize ...

, and that's the trigger to the next step. Thus, an immature ovum can spend up to ~55 years as a primary oocyte (the last ovulation before

menopause Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often ...

Secondary oocyte

The secondary oocyte is the cell that is formed by meiosis I in oogenesis. Thus, it has only one of each pair of homologous chromosomes. In other words, it is haploid. However, each chromosome still has two chromatids, making a total of 46 chromatids (1N but 2C). The secondary oocyte continues the second stage of meiosis (meiosis II), and the daughter cells are one ootid and one

. Secondary oocytes are the immature ovum shortly after ovulation, to

fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...

, where it turns into an ootid. Thus, the time as a secondary oocyte is measured in days. The secondary oocyte is the largest cell in the body, and in humans is just visible to the naked eye.

Ootid

An ''ootid'' is the haploid result of ootidogenesis.yourdictionary
/ref> In oogenesis, it doesn't really have any significance in itself, since it is very similar to the ovum. However, it fills the purpose as the female counterpart of the male

spermatid The spermatid is the haploid male gametid that results from division of secondary spermatocytes. As a result of meiosis, each spermatid contains only half of the genetic material present in the original primary spermatocyte. Spermatids are co ...

in spermatogenesis. Each chromosome is split between the two ootids, leaving only one chromatid per chromosome. Thus, there are 23 chromatids in total (1N). In other words, the ootid is the immature ovum formed shortly after fertilization, but before complete maturation into an ovum. Thus, the time spent as an ootid is measured in minutes.

Ovum

The ootid matures into an ovum.

References

{{DEFAULTSORT:Immature Ovum Developmental biology