title: Ultrastructure of the spermatozoa and spermiogenesis in New Zealand freshwater eels (Anguillidae).
abstract: The spermiogenesis and sperm ultrastructure of Anguilla australis schmidtii and A. dieffenbachii is described. During spermiogenesis the chromatin material condenses into the crescent-shaped head of the mature sperm. By elongation of the sperm head the mitochondrion is displaced to the anterior of the head remote from the posterior centriolar apparatus. A ciliary rootlet becomes segregated during spermiogenesis to form a membrane covered, striated, rod-like appendage. From the proximal centriole arise two sets of filaments, each containing three subfibrils. One group of five filaments extends anteriorly along the inner concave side of the head. A group of four modified filaments pass along the outer, convex, side. The middle subfibril B of each triplet in the group of four filaments is flattened and joins the two subfibrils A and B, forming a binocular shaped structure. The motile flagellum has a 9+0 axonemal pattern.
mesh_terms: D000811:Anguilla; D000818:Animals; D008297:Male; D008928:Mitochondria / Q000648:ultrastructure; D013087:Spermatids / Q000648:ultrastructure; D013091:Spermatogenesis; D013094:Spermatozoa / Q000648:ultrastructure*