title: Ultrastructure of spermiogenesis and spermatozoa of Discocotyle sagittata (Monogenea: Polyopisthocotylea: Discocotylinea).
abstract: Ultrastructural analysis revealed that the spermatozoon of Discocotyle sagittata (Leuckart, 1842) is composed of two parallel axonemes, mitochondrion, nucleus and cortical microtubules. The nucleus, which occupies a central/distal position and has an unusual crescent-shaped profile, is slightly shorter than the mitochondrial rod. The two axonemes, which are of unequal length, and the cortical microtubules (up to 68 forming a continuous ring in the principal region) extend almost the entire length of the spermatozoon. A fold of the plasma membrane creates a unilateral flange or undulating membrane. Epifluorescence microscopy indicated that spermatogenesis gives rise to clusters of 64 spermatids connected to a common cytophore. Spermiogenesis and the structure of the filiform sperm of D. sagittata conform to the typical polyopisthocotylean pattern.
authors.affiliation: School of Biological Sciences, University of Bristol, UK. cablej@cardiff.ac.uk
authors.forename: J
authors.initials: J
authors.lastname: Cable
authors.forename: R C
authors.initials: RC
authors.lastname: Tinsley
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D017686:Oncorhynchus mykiss / Q000469:parasitology; D010986:Platyhelminths / Q000502:physiology / Q000648:ultrastructure*; D013087:Spermatids / Q000648:ultrastructure; D013090:Spermatocytes / Q000648:ultrastructure; D013091:Spermatogenesis; D013094:Spermatozoa / Q000648:ultrastructure*