Hunter R H, Fléchon B, Fléchon J E
University of Edinburgh, Scotland, UK.
Tissue Cell. 1991;23(5):641-56. doi: 10.1016/0040-8166(91)90020-t.
In cows undergoing spontaneous oestrous cycles and mated during the first 6 hours of oestrus, the distribution of spermatozoa in the oviduct isthmus and changes in their surface membranes and neighbouring epithelium have been examined shortly before and after ovulation. In agreement with previous histological studies, relatively few spermatozoa were detected in the oviduct lumen: most were located in the caudal isthmus before ovulation, frequently among folds and in the presence of a viscous secretion. A majority of spermatozoa in this region showed strands and droplets of secretory material distributed over the anterior portion of an intact head before ovulation, whereas distribution of material over the post-nuclear cap of spermatozoa close to vesiculation or already acrosome-reacted was characteristic of the post-ovulatory situation. These changes in sperm head membranes were viewed as an expression of the completion of capacitation, and seemingly permit microvillous engagement with the rostral tip of the head. In conjunction with a narrow lumen and viscous secretions in the caudal isthmus, microvilli may thus serve to regulate periovulatory sperm progression towards the site of fertilisation, and be the basis of intermittent phases of adhesion to the oviduct epithelium as seen by phase-contrast microscopy. Although cilia do not similarly engage the heads of bull spermatozoa (cf. boar spermatozoa), they may act to regulate progression of capacitated spermatozoa by contacting the principal piece of the flagellum. In the light of these observations, changes in the molecular composition of sperm surface domains during the process of capacitation in vivo now require specific definition.
在经历自发发情周期且在发情期的前6小时内交配的母牛中，在排卵前后不久检查了输卵管峡部精子的分布及其表面膜和邻近上皮的变化。与先前的组织学研究一致，在输卵管腔中检测到的精子相对较少：大多数精子在排卵前位于峡部尾部，经常位于褶皱之间且存在粘性分泌物。该区域的大多数精子在排卵前显示分泌物质的条带和液滴分布在完整头部的前部，而靠近囊泡化或已经发生顶体反应的精子核后帽上的物质分布是排卵后的特征。精子头部膜的这些变化被视为获能完成的一种表现，并且似乎允许微绒毛与头部的吻端结合。结合峡部尾部狭窄的管腔和粘性分泌物，微绒毛因此可能有助于调节排卵前后精子向受精部位的进展，并且是相差显微镜下所见的精子与输卵管上皮间歇性粘附阶段的基础。虽然纤毛不会以同样的方式与公牛精子的头部结合（参见公猪精子），但它们可能通过接触鞭毛的主段来调节获能精子的进展。鉴于这些观察结果，现在需要对体内获能过程中精子表面区域分子组成的变化进行具体定义。
