Department of Biological Sciences, Purdue University, West Lafayette, Indiana.
Mol Reprod Dev. 2020 Mar;87(3):341-349. doi: 10.1002/mrd.23331. Epub 2020 Mar 27.
The egg's blocks to polyspermy (fertilization of an egg by more than one sperm) were originally identified in marine and aquatic species with external fertilization, but polyspermy matters in mammalian reproduction too. Embryonic triploidy is a noteworthy event associated with pregnancy complications and loss. Polyspermy is a major cause of triploidy with up to 80% of triploid conceptuses being the result of dispermic fertilization. The mammalian female reproductive tract regulates the number of sperm that reach the site of fertilization, but mammals also utilize egg-based blocks to polyspermy. The egg-based blocks occur on the mammalian egg coat (the zona pellucida) and the egg plasma membrane, with apparent variation between different mammalian species regarding the extent to which one or both are used. The zona pellucida block to polyspermy has some similarities to the slow block in water-dwelling species, but the mammalian membrane block to polyspermy differs substantially from the fast electrical block that has been characterized in marine and aquatic species. This review discusses what is known about the incidence of polyspermy in mammals and about the mammalian membrane block to polyspermy, as well as notes some lesser-characterized potential mechanisms contributing to polyspermy prevention in mammals.
卵对多精入卵（一个卵子被多个精子受精）的阻碍最初在进行体外受精的海洋和水生物种中被发现，但多精入卵在哺乳动物繁殖中也很重要。胚胎三倍体是与妊娠并发症和流产相关的一个显著事件。多精入卵是三倍体的主要原因，多达 80%的三倍体胚胎是双精受精的结果。哺乳动物的雌性生殖道调节到达受精部位的精子数量，但哺乳动物也利用卵源性阻止多精入卵。卵源性阻止多精入卵发生在哺乳动物卵透明带（卵丘细胞外基质）和卵质膜上，不同哺乳动物物种在一种或两种阻止多精入卵的程度上存在明显差异。透明带阻止多精入卵与水生物种的缓慢阻止有一些相似之处，但哺乳动物质膜阻止多精入卵与已在海洋和水生物种中表征的快速电阻止有很大不同。本综述讨论了哺乳动物中多精入卵的发生率以及哺乳动物质膜阻止多精入卵的情况，并指出了一些特征不太明显的潜在机制，这些机制有助于哺乳动物防止多精入卵。
