| 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) |
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| 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) |
| reproductive adaptation | A peculiarity of the reproductive mechanism of a species that results in it being better fitted to its environment (for example, prolonged seed dormancy). (09 Oct 1997) |
| reproductive and urinary physiology | Physiology of the human and animal body, male or female, in the reproductive process and the physiology of the urinary tract. (12 Dec 1998) |
| reproductive assimilation | In sensorimotor theory, an active cognitive process by which past experience is applied to novel situations. (05 Mar 2000) |
| reproductive cells | 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 control agents | Substances used either in the prevention or facilitation of pregnancy. (12 Dec 1998) |
| reproductive cycle | The cycle which begins with conception and extends through gestation and parturition. (05 Mar 2000) |
| reproductive endocrinologist | An ob-gyn who specialises in the treatment of hormonal disorders that affect reproductive function. (09 Oct 1997) |
| reproductive history | An important aggregate factor in epidemiological studies of women's health. The concept usually includes the number and timing of pregnancies and their outcomes, the incidence of breast feeding, and may include age of menarche and menopause, regularity of menstruation, fertility, gynecological or obstetric problems, or contraceptive usage. (12 Dec 1998) |
| reproductive medicine | A medical-surgical specialty concerned with the morphology, physiology, biochemistry, and pathology of reproduction in man and other animals, and on the biological, medical, and veterinary problems of fertility and lactation. It includes ovulation induction, diagnosis of infertility and recurrent pregnancy loss, and assisted reproductive technologies such as embryo transfer, in vitro fertilization, and intra-fallopian transfer of zygotes. (12 Dec 1998) |
| reproductive nucleus | <cell biology> The smaller nucleus in ciliate protozoans, fully active in inheritance and passed after meiosis to conjugating pairs. Gives rise to the macronucleus or macronuclei. Genes in the micronucleus are not actively transcribed. (18 Nov 1997) |
| reproductive ratio | <epidemiology> 1. Basic reproductive ratio , Ro , a dimensionless parameter which encapsulates the biological details of different transmission mechanisms. For microparasites, Ro , is defined as the average number of secondary cases of infection to which one primary case gives rise throughout its infectious period if introduced into a defined population consisting solely of susceptible individuals. For macroparasites, Ro , is the average number of female offspring (or just offspring in the case of hermaphroditic species) produced throughout the lifetime of a mature female parasite, which themselves achieve reproductive maturity in the absence of density-dependent constraints on the parasite establishment, survival or reproduction. Also known as the basic reproduction rate, number. 2. Effective reproductive ratio , R , The number of secondary cases (microparasites) or female offspring (macroparasites) produced in a host population not consisting entirely of susceptible individuals (microparasites) or within which density dependent constraints limit parasite population growth (macroparasites). Under conditions of stable endemic infection, R=1. (05 Dec 1998) |