Immature ovum

Revision as of 16:18, 9 August 2012 by WikiBot (talk | contribs) (Robot: Automated text replacement (-{{SIB}} + & -{{EH}} + & -{{EJ}} + & -{{Editor Help}} + & -{{Editor Join}} +))
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

WikiDoc Resources for Immature ovum

Articles

Most recent articles on Immature ovum

Most cited articles on Immature ovum

Review articles on Immature ovum

Articles on Immature ovum in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Immature ovum

Images of Immature ovum

Photos of Immature ovum

Podcasts & MP3s on Immature ovum

Videos on Immature ovum

Evidence Based Medicine

Cochrane Collaboration on Immature ovum

Bandolier on Immature ovum

TRIP on Immature ovum

Clinical Trials

Ongoing Trials on Immature ovum at Clinical Trials.gov

Trial results on Immature ovum

Clinical Trials on Immature ovum at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Immature ovum

NICE Guidance on Immature ovum

NHS PRODIGY Guidance

FDA on Immature ovum

CDC on Immature ovum

Books

Books on Immature ovum

News

Immature ovum in the news

Be alerted to news on Immature ovum

News trends on Immature ovum

Commentary

Blogs on Immature ovum

Definitions

Definitions of Immature ovum

Patient Resources / Community

Patient resources on Immature ovum

Discussion groups on Immature ovum

Patient Handouts on Immature ovum

Directions to Hospitals Treating Immature ovum

Risk calculators and risk factors for Immature ovum

Healthcare Provider Resources

Symptoms of Immature ovum

Causes & Risk Factors for Immature ovum

Diagnostic studies for Immature ovum

Treatment of Immature ovum

Continuing Medical Education (CME)

CME Programs on Immature ovum

International

Immature ovum en Espanol

Immature ovum en Francais

Business

Immature ovum in the Marketplace

Patents on Immature ovum

Experimental / Informatics

List of terms related to Immature ovum


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

Cell type ploidy/chromosomes chromatids Process Process completion
Oogonium diploid/46 2N Oocytogenesis (mitosis) third trimester
primary Oocyte diploid/46 4N Ootidogenesis (meiosis 1) (Folliculogenesis) Dictyate in prophase I until ovulation
secondary Oocyte haploid/23 2N Ootidogenesis (meiosis 2) Halted in metaphase II until fertilization
Ootid haploid/23 1N ? Minutes after fertilization
Ovum haploid/23 1N

Oogonium

Oogonia are the cells that turn into primary oocytes in oogenesis[1]. They are diploid, i.e. containing both pairs of homologous chromosomes. There are 23 chromosome pairs. Thus there are 46 chromosomes. Each chromosome, however, hasn't yet duplicated itself. Thus, there are only one chromatid on each chromosome, making the total quantity of chromatids 46. This is twice the number of chromosome pairs (2N).

Timeline

Oogonia are created in early embryonic life. All have turned into oogonia at late fetal age.

Primary oocyte

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 chomatids, i.e. 92 chromatids all in all (4N).

When meiosis I is completed, one secondary oocyte and one polar body is created.

Timeline

Primary oocytes have been created in late fetal life. This is the stage where immature ova spend most of their lifetime, more specifically in prophase I of meiosis. The halt is called dictyate. Most degenerate by atresia, but a few go through ovulation, 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).

Secondary oocyte

The secondary oocyte is the cell that is formed by meiosis I in oogenesis[3]. 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 (2N). The secondary oocyte continues the second stage of meiosis (meiosis II), and the daughter cells are one ootid and one polar body.

Timeline

Secondary oocytes are the immature ovum shortly after ovulation, to fertilization, where it turns into an ootid. Thus, the time as a secondary oocyte is measured in days.

Size

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[4]. In oogenesis, it deosn'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 in spermatogenesis.

Each chromosome is split between the two ootids, leaving only one chromatid per chromosome. Thus, there are 23 chromatids in total (1N).

Timeline

In other words, the ootid is the immature ovum from 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

Template:Female reproductive system

Template:WH Template:WikiDoc Sources