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Multiple acrosomal vesicles and their differentiation during spermiogenesis in Ascidia zara and Ascidia gemmata (Ascidiacea, Tunicata)
Author(s) -
Fujii Kazue,
Fukumoto Makoto
Publication year - 1999
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/(sici)1097-4687(199911)242:2<101::aid-jmor3>3.0.co;2-3
Subject(s) - spermiogenesis , biology , acrosome , vesicle , spermatid , sperm , microbiology and biotechnology , anatomy , spermatozoon , nucleus , botany , genetics , membrane
A fully differentiated spermatozoon of both Ascidia zara and Ascidia gemmata is approximately 35 μM long. It contains a head and a tail lacking a midpiece. The head (approximately 4 μM long for A. zara and 5 μM long for A. gemmata ) contains an elongated nucleus and a single mitochondrion that flanks the nucleus. Multiple acrosomal vesicles (three or four in number) are present at the apex of the sperm head in both species. Each vesicle is approximately 50 × 50 × 60 nm, and contains moderately electron‐dense material. During spermiogenesis of A. zara , three or four vesicles appear in a blister of an early stage spermatid. These vesicles transform into multiple acrosomal vesicles without fusing with each other. Spermiogenesis and acrosome differentiation are similar in A. gemmata and A. zara . Three types of acrosome differentiation in ascidians are described. J. Morphol. 242:101–106, 1999. © 1999 Wiley‐Liss, Inc.