組培人體胚胎學(xué)ppt課件-資料下載頁
2025-01-05 16:18本頁面
【正文】 has been recovered and examined. Cause Many chromosomal anomalies arise during gametogenesis and cleavage Down syndrome is an example of a disorder caused by an error during meiosis or mitosis Chromosome analysis can determine the parental source and the defective chromosome and provides a basis for diagnosis an possible treatment (2)Contraceptive techniques interfere with a wide variety of reproductive mechanisms 受精與節(jié)育和不孕不育 Despite the high rate of spontaneous abortion, human reproductive efficiency is very high. Methods : （ 1） Barrier contraceptives prevent the sperm from reaching the egg.(2)The birth control pill prevent ovulation.(3)injected or implanted sources of progestin deliver a chronic antiovulatory dose. （ (4)Nonmedicated IUDs may interfere with conception through effects on both sperm and egg. (5)The antiprogesterone pound RU486 is an abortifacient . (6) sterilization is used by about one third of american couples. (7)new methods of contraception are needed. Infertile(15%30%in American ) The maturation of human gametes and early embryos can now be supported outside the body to assist infertile couples. An oocyte can be fertilized in vitro and then implanted in the uterus. In vitro fertilization and embryo transfer(IVF). Gametes or zygotes can be introduced directly into the ampulla of the oviduct.
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