Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa.
Theriogenology. 2011 Oct 15;76(7):1275-83. doi: 10.1016/j.theriogenology.2011.05.034. Epub 2011 Jul 12.
The accurate assessment of avian sperm abnormalities is hampered by a lack of descriptive data and by the confusing terminology currently in use. Critical appraisal of semen samples from the distal ductus deferens of the emu revealed that two closely related yet separate (distinct) defects previously collectively referred to as "bent sperm" or "crooked-necked sperm" could be identified by light and electron microscopy. Head-base bending typically involved a 180° bend at the base of the nucleus which placed the head and midpiece into close apposition and parallel to each other. No part of the neck or midpiece was involved and bending was restricted exclusively to the base of the nucleus. Incomplete chromatin condensation was always associated with the bend. Disjointed sperm, which superficially resembled "bent" sperm, showed complete separation of the neck from the head-base at the level of the connecting piece. All structural elements of the neck region appeared normal. In both defects the region of contact between the head (nucleus) and the neck/midpiece was enclosed as a unit by the plasmalemma. Both defects were observed to originate in the testis; however, their subsequent expression in the ductus deferens cannot be ruled out. These results confirm that head-base bending of emu sperm represents a head defect, whereas disjointed sperm should be classified as a tail (neck/midpiece) defect.
对禽类精子畸形的准确评估受到缺乏描述性数据和当前使用的混淆术语的阻碍。对鸸鹋远端输精管精液样本的批判性评估表明，以前被统称为“弯曲精子”或“歪颈精子”的两种密切相关但又独立（不同）的缺陷可以通过光镜和电镜来识别。头部-基底弯曲通常涉及在核基底处发生 180°弯曲，使头部和中段彼此紧密贴合并彼此平行。颈部或中段的任何部分都不参与，弯曲仅限于核基底。不完全染色质浓缩总是与弯曲相关。脱节精子，表面上类似于“弯曲”精子，在连接片水平处显示颈部与头部-基底完全分离。颈部区域的所有结构元素似乎都正常。在这两种缺陷中，头部（核）和颈部/中段之间的接触区域都被质膜作为一个单元封闭。这两种缺陷都被观察到起源于睾丸；然而，不能排除它们在输精管中的后续表达。这些结果证实，鸸鹋精子的头部-基底弯曲代表头部缺陷，而脱节精子应归类为尾部（颈部/中段）缺陷。
