title: Ultrastructure and motility of the spermatozoa of Polypedates leucomystax (Amphibia, Anura, Rhacophoridae).
abstract: Sperm morphology is thought to be shaped by evolutionary pressure from the fertilization environment. Rhacophoridae (Amphibia, Anura) include both foam-nesting and nonfoam-nesting species and exhibit a variety of sperm morphologies. Here, we examine the sperm morphology and motility of a foam-nesting Rhacophoridae frog, Polypedates leucomystax. Their spermatozoa have a sickle-shaped head and a thick tail containing two axonemes with their doublet microtubule ones (Db1s) facing one another. These two axonemes are surrounded by hundreds of satellite microtubules that form a hexagonal lattice structure. The spermatozoa move spirally by directly converting their tail movements into propulsion force, similar to the movement of the sickle-shaped spermatozoa of Xenopus laevis. By comparing the spermatozoa of P. leucomystax to those of other foam-nesting Rhacophoridae frogs, Rhacophorus and Chiromantis, and to the nonfoam-nesting Rhacophoridae frog, Buergeria buergeri, we found the following: (i) Spermatozoa of foam-nesting Rhacophoridae share common morphological features, a pair of axonemes and crystallized satellite microtubules. (ii) Spermatozoa of nonfoam-nesting Rhacophoridae do not exhibit these features. (iii) Sperm motility in foam-nesting Rhacophoridae is adapted to viscous environments. (iv) A diversity of sperm morphology and motility exists even among foam-nesting Rhacophoridae frogs. (v) The spermatozoa of Rhacophorus are more adapted to the foam nest than the spermatozoa of Polypedates.
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Muto
authors.forename: Hiroshi Y
authors.initials: HY
authors.lastname: Kubota
mesh_terms: D000818:Animals; D001001:Anura / Q000502:physiology*; D054468:Axoneme / Q000502:physiology / Q000648:ultrastructure; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology* / Q000648:ultrastructure*