Long J A, Wildt D E, Wolfe B A, Critser J K, DeRossi R V, Howard J
National Zoological Park and Conservation and Research Center, Smithsonian Institution, Washington, District of Columbia 20008, USA.
Biol Reprod. 1996 Mar;54(3):638-46. doi: 10.1095/biolreprod54.3.638.
The efficiency of sperm capacitation and of the acrosome reaction was studied in the teratospermic domestic cat to evaluate further the etiology of compromised zona pellucida penetration and oocyte fertilization. Specific objectives were to compare normospermic and teratospermic cat ejaculates for 1) the kinetics and timing of sperm capacitation in vitro as determined by an ionophore-induced acrosome reaction; 2) the incidence of spontaneous acrosomal loss; 3) the ability of capacitated, swim-up processed sperm to acrosome-react in response to chemical (calcium ionophore) or physiological (solubilized zonae pellucidae) inducers; and 4) differences in acrosomal ultrastructure by use of transmission electron microscopy (TEM). Acrosomal status was determined with the fluorescent probe Arachis hypogaea (peanut) agglutinin. The timing of in vitro capacitation differed (p < 0.05) between cat populations. Normospermic samples were capacitated at 2.0 h postcentrifugation, whereas teratospermic samples required 2.5 h to become capacitated. At 2.5 h, sperm from teratospermic males were less capable (p < 0.05) of completing the acrosome reaction after ionophore exposure (49.3 +/- 8.0%) than sperm from normospermic males (73.3 +/- 3.8%). Levels of spontaneous acrosomal loss/reaction over time were similar (p > 0.05) between cat groups (range, 7.6-17.8%). In swim-up separated sperm from normospermic cats, ionophore A23187 was a more potent inducer (p < 0.05) of the acrosome reaction (70.1 +/- 6.5%) than solubilized zonae pellucidae (31.1 +/- 1.2%). Swim-up separated sperm from teratospermic cats, however, were compromised in the ability to acrosome react, regardless of inducer (ionophore, 23.9 +/- 3.3%; solubilized zonae pellucidae, 23.9 +/- 4.7%; p > 0.05). Sperm motility patterns over time indicated that differences in acrosomal status were not influenced by cell death. The frequency of abnormal acrosomes detected by TEM was higher (p < 0.05) in teratospermic (30.0 +/- 3.9%) than in normospermic (3.1 +/- 1.3%) samples. Swim-up separation failed to reduce (p > 0.05) the proportion of sperm cells with malformed acrosomes (swim-up, 33.5 +/- 3.5%; washed, 26.6 +/- 4.6%). These results indicate that sperm from teratospermic cats exhibit a high incidence of malformed acrosomes detectable only at the ultrastructural level. Nevertheless, acrosomal dysfunction is not related exclusively to structural defects because > 40.0% of swim-up separated sperm with structurally normal acrosomes still are incapable of completing the acrosome reaction. This suggests that compromised capacitation and acrosomal dysfunction may be responsible for low fertilization success in the teratospermic domestic cat.
在畸形精子症家猫中研究了精子获能效率和顶体反应，以进一步评估透明带穿透受损和卵母细胞受精的病因。具体目标是比较正常精子症和畸形精子症家猫射精样本，以研究：1）通过离子载体诱导的顶体反应确定的体外精子获能动力学和时间；2）自发顶体丢失的发生率；3）经上浮处理的获能精子对化学诱导剂（钙离子载体）或生理诱导剂（溶解的透明带）发生顶体反应的能力；4）使用透射电子显微镜（TEM）观察顶体超微结构的差异。用荧光探针花生凝集素确定顶体状态。家猫群体之间体外获能时间不同（p<0.05）。正常精子症样本在离心后2.0小时获能，而畸形精子症样本需要2.5小时才能获能。在2.5小时时，畸形精子症雄性的精子在离子载体暴露后完成顶体反应的能力（49.3±8.0%）低于正常精子症雄性的精子（73.3±3.8%）（p<0.05）。随着时间推移，家猫组之间自发顶体丢失/反应水平相似（p>0.05）（范围为7.6-17.8%）。在正常精子症家猫经上浮分离的精子中，离子载体A23187比溶解的透明带更能有效诱导顶体反应（p<0.0（70.1±6.5%）（31.1±1.2%）。然而，畸形精子症家猫经上浮分离的精子，无论诱导剂如何，顶体反应能力均受损（离子载体，23.9±3.3%；溶解的透明带，23.9±4.7%；p>0.05）。随着时间推移的精子运动模式表明，顶体状态差异不受细胞死亡影响。通过TEM检测到的畸形顶体频率在畸形精子症样本（30.0±3.9%）中高于正常精子症样本（3.1±1.3%）（p<0.05）。上浮分离未能降低（p>0.05）畸形顶体精子细胞的比例（上浮后，33.5±3.5%；洗涤后，26.6±4.6%）。这些结果表明，畸形精子症家猫的精子仅在超微结构水平上表现出高比例的畸形顶体。然而，顶体功能障碍并非完全与结构缺陷相关，因为超过40.0%经上浮分离且顶体结构正常的精子仍无法完成顶体反应。这表明获能受损和顶体功能障碍可能是畸形精子症家猫受精成功率低的原因。
