北草蜥精子的超微结构——兼评不同类群蜥蜴精子形态的差异

Ultrastructure of the Spermatozoon of the Northern Grass Lizard (Takydromus septentrionalis) with Comments on the Variability of Sperm Morphology Among Lizard Taxa

应用透射电镜对北草蜥精子的超微结构研究结果表明,北草蜥精子头部顶体囊始终呈圆形,由皮质 和髓质组成;顶体囊单侧脊的皮质与髓质间具电子透亮区;穿孔器1个,无穿孔器基板;具顶体下腔;细胞核 长形,核内小管缺,核前电子透亮区缺,核肩圆。尾部颈段具片层结构。中段短,多层膜结构缺;纵切面上具 2层线粒体;横切面上每圈线粒体6个;2组致密体,具连续的环状结构;线粒体与环状结构的排列模式:rsl／ mil、rs2／mi2;纤维鞘伸入中段,具终环。主段前面部分具薄的细胞质颗粒区;纤维3和8至主段前端消失; 轴丝呈“9+2”型。蜥蜴科内不同种类的线粒体数目不同,但都具有2组致密体。不同类群蜥蜴的顶体囊、顶 体下腔、核前电子透亮区、穿孔器基板、核肩,以及线粒体与致密体的数目和排列方式等精子超微结构特征都 为研究蜥蜴的系统发生提供了辅助信息。

We studied the ultrastructure of the spermatozoon of northern grass lizards （ Takydromus septentrionalis, n = 5） collected in April 2003 from a population in Wenzhou, Zhejiang, eastern China. The mature spermatozoa are characterized by： A circular acrosome; an acrosomal vesicle divided into cortex and medulla; the unilateral ridge of the acrosome vesicle divided into cortex and medulla, the electron-lucent zone between them ; a prenuclear perforatorium, absence of the perforatorium base plate ; presence of the subacrosomal space ; an elongated nucleus, absence of a endonuclear canal ; absence of epinuclear lucent zone ; rounded nuclear shoulders. A bilateral stratified laminar structure within the neck region. A short midpiece; absence of multilaminar membranes; in longitudinal section, two tiers of mitochondria, in transverse section, six mitochondria with linear cristae; the presence of two dense body groups, the ring structure consisting of the complete ring; the arrangement pattern of the ring structure and mitochondria in rs1/mi1 and rs2/mi2; a fibrous sheath in the midpiece ; presence of an annulus. A thin granular zone of cytoplasm at the anterior portion of the principal piece ; the enlarged fiber 3 and fiber 8 disappearing at the anterior portion of the principal piece ; the axoneme complex having an usual 9 ＋ 2 pattern. Within lacertid lizards, sperms differ among species in the number of mitochondria, but in all species studied so far, there are two groups of dense bodies. However, lizards of different taxa differ, in various degrees, in such sperm morphological traits as acrosome vesicle, subacrosomal space, epinuclear lucent zone, perforatorium base plate, nuclear shoulder and number and arrangement of mitochondria and dense bodies. These differences suggest that sperm morphology provides additional information which one may use to study the phylogeny of lizards.