n. the caplike structure on the front end of a spermatozoon. It breaks down just before fertilization (the acrosome reaction), releasing a number of enzymes that assist penetration between the follicle cells that still surround the ovum. Failure of the acrosome reaction is a cause of male infertility (see also andrology).
n. 1. the study of male infertility and erectile dysfunction. *Seminal analysis reveals the presence of gross abnormalities in the shape and motility of spermatozoa, as well as their concentration in the semen, but further procedures are required to diagnose the underlying causes of the sperm dysfunction. These include the diagnosis of abnormalities in the genital tract (e.g. varicocele, obstruction of the vas deferens), which may be corrected surgically, and testing for the presence of antisperm antibodies in the semen and for the ability of the sperm to penetrate the cervical mucus, as well as for the presence of hormonal disorders. More sophisticated techniques include computer-assisted quantitative motility measurements, which monitor the precise speed and motility patterns of individual sperm; biochemical tests for the production of free oxygen radicals, which cause damage to developing sperm; and *acrosome-reaction assays, which reveal the ability of the sperm to penetrate the barriers surrounding the ovum. The development of all these techniques has enabled the identification of several previously undiagnosed causes of infertility and the selection of treatments most likely to succeed in remedying them. 2. the study of androgen production and the relationship of plasma androgen to androgen action. This study is necessary to understand *hirsutism and other conditions caused by abnormal androgen production.... andrology
(IUI) a procedure for assisting conception in which carefully washed spermatozoa are injected into the uterus through the vagina at the time of ovulation, which is induced and monitored (using ultrasound) to determine the day of insemination. This procedure is used in cases of male infertility due to inability of the sperm to penetrate the cervical mucus or the barriers surrounding the ovum, in which case the sperm may be treated in vitro to improve their motility and *acrosome reaction. IUI is also used for donor insemination.... intrauterine insemination
(sperm) n. (pl. spermatozoa) a mature male sex cell (see gamete). The tail of a sperm enables it to swim, which is important as a means for reaching and fertilizing the ovum (although muscular movements of the uterus may assist its journey from the vagina). See also acrosome; fertilization.... spermatozoon
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