冷冻及复温后人精子超微结构变化的研究

STUDY ON THE ULTRASTRUCTURAL CHANGES OF HUMAN SPERMATOZOA AFTER FREEZING AND THAWING

本文研究了冷冻及复温过程中人精子超微结构的变化.用甘油-卵黄-三羟甲基氨基甲烷-葡萄糖-柠檬酸混合液或纯甘油作精子冷冻保护剂,采用阶段降温法。标本在-196℃液氮中贮存一周后.37℃水浴中复温5～10分钟.透射电镜(TEM)下观察.精子超微结构变化主要在头部,可见顶体前段及质膜肿胀,顶体外膜破裂,顶体物质流失;甚至顶体内膜及核膜破损,丧失成为裸核精子。与新鲜精液相比.有完整质膜.顶体的精子百分比明显下降(P<0.01)。线粒体基质局部透亮,呈空泡状改变,并可见细小颗粒物质沉积.尾部轴丝“9+2”结构存在;质膜和核之间可见尾结构。精子头部结构完整率与精子存活率呈正相关(r=0.88 P<0.01).结果表明同一供者的冻精作人工授精,其成功率必然低于鲜精的成功率;它也可能是一般冻精人工授精成功率低于鲜精的原因.

The Ultrastructure changes of human spermatozoa at various stages of the freezing and thawing process were studied. The most conspicuous changes were found in the sperm head. The anterior seg- ment of the acrosome became increasingly swollen, the plasma membrane swollen or damaged, and the acrosomal material was leaked out. Even inner acrosomal membranes and nuclear membrane could also be damaged (nudesperm.) The percentage of spermatozoa with intact plasma membrane or intact acrosomes was significantly reduced in frozen/thawed semen than in fresh semen samples(P<0.01). The mitochondrial matrix became more bright, often in localized areas, in which finely granulated material was deposited, The general 9 + 2 pattern of the axoneme was unchanged. The coiled tail structures were present between sperm membranes and the nucleus, A positive correlation was observed between the rate of intact sperm head and sperm viability It may be the reason that the fertility rate of frozen/thawed semen is lower than that of the fresh semen.