Ultrastructure of spermatozoa of the Chinese skink Eumeces chinensis

Abstract

We studied the ultrastructure of epididymal spermatozoa of Chinese skinks Eunaeces chinensis (n = 8) collected in April 2003 from a population in Lishui, Zhejiang, eastern China. The mature spermatozoa are characterized by: a depressed acrosome at the anterior portion; an acrosomal vescile divided into cortex and medulla; a moderately oblique prenuclear perforatorium with a sharp tip; a stopper-like perforatorium base plate; an elongated nucleus; absence of a endonuclear cannal; an obscure epinuclear lucent zone; rounded nuclear shoulders; a coned nuclear fossa; a bilateral stratified laminar structure within neck region; a long axis of the proximal centriole almost vertical to that of the distal centriole; nine peripheral dense fibres connecting inward with the corresponding 9 triplets of the distal centriole and backward with the doublets of the axoneme; central fibres connecting with the two central singlets; a short midpiece; absence of multilaminar membranes; columnar mitochondria with linear cristae; each intermitochondrial ring structure consisting of the incomplete ring of irregularly ovoid dense bodies; a fibrous sheath into the midpiece; presence of an annulus; the arrangement pattern of the ring structure and mitochondria in rs1 / mi1, rs2 / mi2, rs3 / mi3, and rs4 / mi4; 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. The sperm of E. chinensis characteristically has a stopper-like perforatorium base plate, incomplete rings constructed by dense bodies, a fibrous sheath starting from mi2. These traits are absent in species within the Sphenomorphus-Egernia group and the Eugongylus group. Thus, we conclude that the sperm of E. chinensis differs from that of the aforementioned two skink groups. Evidence of spermatozoa) autapomorphies is not found in sincid skinks.