Baccetti B, Burrini A G, Falchetti E
CNR Center for the Study of Germinal Cells, Siena, Italy.
Biol Cell. 1991;71(1-2):209-16. doi: 10.1016/0248-4900(91)90067-w.
In this paper the authors describe the ultrastructure of the mature spermatozoon and the spermatid in Struthio camelus and Dromaius novaehollandiae. The first species is characterized by a rod-like perforatorium within an endonuclear canal in the anterior third of the nucleus, while the second is characterized by an extremely reduced completely extranuclear perforatorium. Other differences are in the sperm dimensions, the number of mitochondria and the length of the axonemal accessory fibers. Considering both the present data and previous findings, Palaeognath birds appear to be a peculiar and monophyletic group, characterized by: 1), a conical acrosome surrounding the nucleus; 2), a fibrous sheath around most of the axoneme; and 3), an elongated distal centriole occupying the entire midpiece. Within this group, Tinamiformes seem to be more primitive than Struthioniformes. In the latter order Dromaius is distinctly different from the reduced Struthio and Rhea which are closely related to one another by the presence of a rod-like endonuclear perforatorium.
在本文中，作者描述了鸵鸟和鸸鹋成熟精子及精细胞的超微结构。第一种物种的特征是在细胞核前三分之一的核内通道中有一个棒状穿孔器，而第二种物种的特征是完全位于核外的穿孔器极度退化。其他差异在于精子尺寸、线粒体数量以及轴丝附属纤维的长度。综合目前的数据和先前的研究结果，古颚总目鸟类似乎是一个独特的单系类群，其特征为：1）围绕细胞核的锥形顶体；2）大部分轴丝周围的纤维鞘；3）占据整个中段的细长远端中心粒。在这个类群中，䳍形目似乎比鸵形目更为原始。在鸵形目中，鸸鹋与退化的鸵鸟和美洲鸵鸟明显不同，后两者因存在棒状核内穿孔器而彼此密切相关。
