Oocyte selection is a procedure that is performed prior to

in vitro fertilization In vitro fertilisation (IVF) is a process of fertilisation where an egg is combined with sperm in vitro ("in glass"). The process involves monitoring and stimulating an individual's ovulatory process, removing an ovum or ova (egg or eggs) ...

, in order to use

oocytes 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 female g ...

with maximal chances of resulting in pregnancy. In contrast,

embryo selection In vitro fertilisation (IVF) is a process of fertilisation where an egg is combined with sperm in vitro ("in glass"). The process involves monitoring and stimulating an individual's ovulatory process, removing an ovum or ova (egg or eggs) f ...

takes place ''after'' fertilization. __TOC__

Techniques

Chromosomal evaluation may be performed. Embryos from rescued in vitro-matured

metaphase II 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 res ...

(IVM-MII) oocytes show significantly higher fertilization rates and more blastomeres per embryo compared with those from arrested

metaphase I 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 resu ...

(MI) oocytes (58.5% vs. 43.9% and 5.7 vs. 5.0, respectively). Also, morphological features of the oocyte that can be obtained by standard

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...

polarized light microscopy Polarized light microscopy can mean any of a number of optical microscopy techniques involving polarized light. Simple techniques include illumination of the sample with polarized light. Directly transmitted light can, optionally, be blocked wit ...

. However, there is no clear tendency in recent publications to a general increase in predictive value of morphological features. Suggested techniques include ''

zona pellucida The zona pellucida (plural zonae pellucidae, also egg coat or pellucid zone) is a specialized extracellular matrix that surrounds the plasma membrane of mammalian oocytes. It is a vital constitutive part of the oocyte. The zona pellucida first ...

imaging'', which can detect differences in

birefringence Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive). The birefring ...

between eggs, which is a predictor of compaction,

blastulation Blastulation is the stage in early animal embryonic development that produces the blastula. In mammalian development the blastula develops into the blastocyst with a differentiated inner cell mass and an outer trophectoderm. The blastula (fr ...

and pregnancy. Potentially,

polar body biopsy Polar body biopsy is the sampling of a polar body of an oocyte. It was first applied clinically in humans in 1987 after extensive animal studies. A ''polar body'' is a small haploid cell that is formed concomitantly as an egg cell during oogenesis ...

may be used for molecular analysis, and can be used for preimplantation genetic screening.

References

{{DEFAULTSORT:Oocyte selection Fertility In vitro fertilisation Female genital procedures Cryobiology Fertility medicine Obstetrics Human pregnancy Reproduction