Soley John T
Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
Anim Reprod Sci. 2016 Jun;169:14-23. doi: 10.1016/j.anireprosci.2016.02.006. Epub 2016 Feb 8.
This paper presents an overview of the structure, function and anomalies of the sperm centriolar complex (CC) on a comparative basis between mammals and birds. The information is based on selected references from the literature supplemented by original observations on spermiogenesis and sperm structure in disparate mammalian (cheetah and cane rat) and avian (ostrich, rhea and emu) species. Whereas the basic structure of the CC (a diplosome surrounded by pericentriolar material) is similar in Aves and Mammalia, certain differences are apparent. Centriole reduction does not generally occur in birds, but when present as in oscines, involves the loss of the proximal centriole. In ratites, the distal centriole forms the core of the entire midpiece and incorporates the outer dense fibres in addition to initiating axoneme formation. The elements of the connecting piece are not segmented in birds and less complex in basic design than in mammals. The functions of the various components of the CC appear to be similar in birds and mammals. Despite obvious differences in sperm head shape, the centrosomal anomalies afflicting both vertebrate groups demonstrate structural uniformity across species and display a similar range of defects. Most abnormalities result from defective migration and alignment of the CC relative to the nucleus. The most severe manifestation is that of acephalic sperm, while angled tail attachment, abaxial and multiflagellate sperm reflect additional defective forms. The stump-tail defect is not observed in birds. A comparison of defective sperm formation and centrosomal dysfunction at the molecular level is currently difficult owing to the paucity of relevant information on avian sperm.
本文在哺乳动物和鸟类之间进行比较，概述了精子中心粒复合体（CC）的结构、功能及异常情况。这些信息基于文献中的部分参考文献，并辅以对不同哺乳动物（猎豹和蔗鼠）及鸟类（鸵鸟、美洲鸵鸟和鸸鹋）精子发生和精子结构的原始观察。虽然鸟类和哺乳动物中CC的基本结构（由中心粒周围物质包围的双联体）相似，但也存在一些明显差异。鸟类一般不会发生中心粒减少，但在鸣禽中出现时，会涉及近端中心粒的缺失。在平胸鸟类中，远端中心粒形成整个中段的核心，除了启动轴丝形成外，还并入外致密纤维。鸟类中连接段的元件没有分段，其基本设计比哺乳动物中的更简单。鸟类和哺乳动物中CC各组成部分的功能似乎相似。尽管精子头部形状存在明显差异，但困扰这两个脊椎动物类群的中心体异常在物种间表现出结构一致性，并呈现出类似的一系列缺陷。大多数异常是由于CC相对于细胞核的迁移和排列缺陷所致。最严重的表现是无头精子，而尾部倾斜附着、背轴和多鞭毛精子则反映了其他缺陷形式。鸟类中未观察到残尾缺陷。由于关于鸟类精子的相关信息匮乏，目前很难在分子水平上比较有缺陷的精子形成和中心体功能障碍。
