Bedford J M, Breed W G
Department of Obstetrics and Gynecology, Cornell University Medical College, New York, New York 10021.
Biol Reprod. 1994 Apr;50(4):845-54. doi: 10.1095/biolreprod50.4.845.
The disposition of spermatozoa in the female tract of the dasyurid marsupial, Sminthopsis crassicaudata, was examined before and after ovulation, by transillumination using differential interference optics. At 6-30 h after mating in females with maturing follicles, spermatozoa were restricted to special storage crypts that define the isthmus of the Fallopian tube. These spermatozoa were mostly immotile and were spear shaped, except for 50-200 vanguard spermatozoa within anterior crypts that were T shaped due to a rotation of the head on the tail. After ovulation and arrival of eggs in the narrow upper ovarian segment of the tube, several hundred isthmic spermatozoa migrated to that region, dispersed singly or in small groups of variable motility with some festooned around eggs. Most clearly displayed a T configuration, and subsequently, those remaining in the isthmic crypts also adopted a T shape in situ. The motility of mature epididymal spermatozoa and of those flushed from the isthmus before and after ovulation was similar in vitro, and all were spear shaped except for some T-shaped isthmic spermatozoa recovered after ovulation. However, neither spear- nor T-shaped active isthmic spermatozoa ever adhered to the zona pellucida when incubated with eggs. We conclude that transport to and storage of spermatozoa in the isthmus of the Fallopian tube, and their later migration up to the fertilization site and coincident transformation to a T shape, all are closely regulated by the ovarian follicular cycle in Sminthopsis. Only on reaching the upper ovarian segment of the Fallopian tube do Sminthopsis spermatozoa appear to be able to bind to the egg, when the T shape brings the whole surface area of the acrosome into apposition with the zona pellucida. These observations are discussed with special reference to sperm capacitation, sperm penetration mechanisms, and the different idiosyncratic designs of the sperm head in marsupial and eutherian mammals, respectively.
利用微分干涉光学透照法，在排卵前后对肥尾袋鼬（Sminthopsis crassicaudata）雌性生殖道中的精子分布情况进行了检查。在有成熟卵泡的雌性动物交配后6至30小时，精子被限制在界定输卵管峡部的特殊储存隐窝中。这些精子大多不活动，呈矛状，除了前隐窝内50至200个先锋精子呈T形，这是由于头部在尾部上旋转所致。排卵以及卵子到达输卵管狭窄的卵巢上段后，数百个峡部精子迁移至该区域，单个或成小群分散游动，有些环绕在卵子周围。大多数精子明显呈T形，随后，留在峡部隐窝中的精子也在原位呈现T形。成熟附睾精子以及排卵前后从峡部冲出的精子在体外的活力相似，除了排卵后回收的一些峡部T形精子外，其余均呈矛状。然而，无论是矛状还是T形的活跃峡部精子在与卵子一起孵育时，都从未附着在透明带上。我们得出结论，在肥尾袋鼬中，输卵管峡部对精子的运输和储存，以及它们随后向上迁移至受精部位并同时转变为T形，均受到卵巢卵泡周期的密切调控。只有当到达输卵管的卵巢上段时，肥尾袋鼬精子才似乎能够与卵子结合，此时T形使顶体的整个表面积与透明带并列。分别结合精子获能、精子穿透机制以及有袋类和真兽类哺乳动物精子头部不同的特殊设计对这些观察结果进行了讨论。
