Electron Microscope Unit, Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.
Theriogenology. 2012 Apr 1;77(6):1137-43. doi: 10.1016/j.theriogenology.2011.10.018. Epub 2011 Dec 6.
Abaxial tail implantation is a defect occurring in the neck region of spermatozoa and is characterized by misalignment of the centriolar complex relative to the head base. This defect has been described in a number of mammalian species, but is rarely reported in birds. In this study, a detailed description of the defect in emu sperm is presented as well as morphological evidence of its origin in the testis. Despite their low incidence defective sperm could readily be identified using light (LM) and transmission electron microscopy (TEM). Affected sperm displayed obvious misalignment of the head and flagellum with many cells additionally showing unilateral swelling and caudal extension of the nuclear base. This material overlapped the anterior aspect of the centriolar complex. More subtle forms of the defect which were not resolved by LM were revealed by TEM. Abaxial sperm development could be identified in the testis during the early elongated spermatid stage of spermiogenesis. At this stage the centriolar complex was clearly misaligned with respect to the longitudinal axis of the condensing and elongating nucleus. The rare occurrence and low incidence of this defect in the emu would suggest that it has little effect on fertility.
轴后尾植入是一种发生在精子颈部区域的缺陷，其特征是中心粒复合体相对于头部基底的排列不当。这种缺陷在许多哺乳动物物种中都有描述，但在鸟类中很少报道。在这项研究中，详细描述了鸸鹋精子的缺陷，并提供了其在睾丸中起源的形态学证据。尽管发生率低，但使用光镜（LM）和透射电子显微镜（TEM）很容易识别出有缺陷的精子。受影响的精子显示出头部和鞭毛的明显排列不当，许多细胞还表现出单侧肿胀和核基底的尾部延伸。该物质与中心粒复合体的前侧重叠。TEM 揭示了 LM 无法解决的更细微形式的缺陷。在精子发生的早期伸长精子阶段，可以在睾丸中识别出轴后精子的发育。在这个阶段，中心粒复合体明显与浓缩和伸长核的纵轴错位。这种缺陷在鸸鹋中罕见且发生率低，这表明它对生育能力的影响很小。
