Mafunda Patrick Siyambulela, Maree Liana, Kotze Antoinette, van der Horst Gerhard
Department of Medical Bioscience, University of the Western Cape, Bellville, South Africa; Department of Research and Scientific Services, National Zoological Gardens of South Africa, Pretoria, South Africa.
Department of Research and Scientific Services, National Zoological Gardens of South Africa, Pretoria, South Africa; Genetics Department, University of the Free State, Bloemfontein, South Africa.
Theriogenology. 2017 Sep 1;99:1-9. doi: 10.1016/j.theriogenology.2017.05.009. Epub 2017 May 7.
This study evaluated the semen of two penguin species from separate genera with reference to unique features in sperm structure using light microscopy and transmission electron microscopy. Ejaculates from African penguin (n = 51) and Rockhopper penguin (n = 9) contained on average more than 60% motile spermatozoa and a sperm concentration of 3274 × 10/ml and 1423 × 10/ml, respectively. The percentage progressive motility was similar for the two species as well as all the kinematics parameters. The sperm morphology of these two penguin species is almost identical and largely resembles that of non-passerine birds in terms of the filiform head, small acrosome and mid-piece containing 13 spherical mitochondria, arranged around the proximal and distal centrioles in a single helix. Apart from a shorter mid-piece, penguin sperm morphometrics were similar to other non-passerine birds. The ultrastructure of the sperm principal piece revealed the typical 9 + 2 microtubular arrangement without any outer dense fibres. An unusual feature in both African and Rockhopper penguin spermatozoa was the occurrence of multiple axonemes contained in one plasmalemma in 4% of spermatozoa. These double, triple and quadruple axonemal arrangements have not been described previously albeit multiple tails were reported in other bird species. It is unclear whether such a unique structural feature will be of any advantage for sperm motility and might rather be a result of the absence of sperm competition. Multiple axonemes found in penguin flagella could be an apomorphism that distinguish them from other bird spermatozoa.
本研究利用光学显微镜和透射电子显微镜，参照精子结构的独特特征，对来自不同属的两种企鹅的精液进行了评估。非洲企鹅（n = 51）和跳岩企鹅（n = 9）的射精样本中，平均有超过60%的精子具有运动能力，精子浓度分别为3274×10⁶/ml和1423×10⁶/ml。两种企鹅的渐进性运动百分比以及所有运动学参数都相似。这两种企鹅的精子形态几乎相同，在丝状头部、小顶体和含有13个球形线粒体的中段方面，与非雀形目鸟类的精子形态大体相似，这些线粒体围绕近端和远端中心粒呈单螺旋排列。除了中段较短外，企鹅精子的形态测量与其他非雀形目鸟类相似。精子主段的超微结构显示出典型的9 + 2微管排列，没有任何外部致密纤维。非洲企鹅和跳岩企鹅精子的一个不寻常特征是，在4%的精子中，一个质膜内含有多个轴丝。尽管在其他鸟类中曾报道过有多条尾巴的情况，但此前尚未描述过这种双轴丝、三轴丝和四轴丝的排列。目前尚不清楚这种独特的结构特征是否会对精子运动有任何优势，也可能是缺乏精子竞争的结果。在企鹅鞭毛中发现的多个轴丝可能是一种独特的特征，将它们与其他鸟类的精子区分开来。
