| Barr chromatin body | Condensed chromatin of the inactivated X chromosome in female mammals (Barr body). (18 Nov 1997) |
|---|---|
| chromatin | Stainable material of interphase nucleus consisting of nucleic acid and associated histone protein packed into nucleosomes. Euchromatin is loosely packed and accessible to RNA polymerases, whereas heterochromatin is highly condensed and probably transcriptionally inactive. (18 Nov 1997) |
| chromatin 3'-phosphatase-5'-hydroxy kinase | <enzyme> Hydrolyzes the 3'-phosphate end of a polynucleotide duplex followed by ATP-mediated phosphorylation of the 5'-oh end Registry number: EC 3.1.3.- Synonym: chromatin-phosphatase-hydroxykinase (26 Jun 1999) |
| chromatin body | Barr body, condensed X chromosome in female mammalian cell. (18 Nov 1997) |
| chromatin network | The appearance of basophilic material in the nuclei of many cells after fixation. See: chromatin. (05 Mar 2000) |
| chromatin nucleolus | <cell biology> The central portion of a cells nucleus that typically contains a glob of heterochromatin. Origin: Gr. Soma = body (09 Oct 1997) |
| chromatin particles | Fine bluish dots thought to represent remnants of the nucleus, occasionally seen in stained erythrocytes. (05 Mar 2000) |
| heteropyknotic chromatin | <cell biology, genetics> The chromosomal regions that are condensed during interphase and at the time of nuclear division. They show what is considered an abnormal pattern of staining as opposed to euchromatin. Can be subdivided into constitutive regions (present in all cells) and facultative heterochromatin (present in some cells only). The inactive X chromosome of female mammals is an example of facultative heterochromatin. (18 Nov 1997) |
| sex chromatin | Condensed chromatin of the inactivated X chromosome in female mammals (Barr body). (18 Nov 1997) |
| oxyphil chromatin | Chromatin that stains with acid dyes, as in interphase nuclei. Synonym: oxyphil chromatin. (05 Mar 2000) |
| y chromatin | Brilliantly fluorescent body seen in cells stained with the dye quinacrine which lights up the y chromosomes most brightly. (12 Dec 1998) |
| assisted reproductive technology | Originally, a range of techniques for manipulating eggs and sperm in order to overcome infertility. Encompasses drug treatments to stimulate ovulation; surgical methods for removing eggs (e.g., laparoscopy and ultrasound-guided transvaginal aspiration) and for reimplanting embryos (e.g., zygot intrafallopian transfer (or ZIFT); in vitro and in vivo fertilization (e.g., artificial insemination and gamete intrafallopian transfer (or GIFT); ex utero and in utero foetal surgery; as well as laboratory regimes for freezing and screening sperm and embryos, and micromanipulating and cloning embryos. The field's first major success came in 1978 with the birth of "test-tube baby" Louise Brown, engineered by Steptoe, Edwards, et al., of England. As the technologies spread, they increasingly are being employed for purposes beyond infertility, i.e., to reduce the risk of, or avoid passing on, hereditary disease and to select for infant sex. Further uses that would aim at improving the "quality" of offspring have been widely discussed and raise profound legal and ethical questions. See: eugenics. (05 Mar 2000) |
| basic reproductive rate, ratio | <epidemiology> See Reproductive Ratio. (05 Dec 1998) |
| cells, reproductive | The eggs and sperm are the reproductive cells. Each mature reproductive cell is haploid in that it has a single set of 23 chromosomes. (12 Dec 1998) |
| reproductive | Relating to reproduction. (05 Mar 2000) |