15 NOVEMBER 1999
F. Lahnsteiner, R.A. Patzner-1999
Journal of Fish Biology, 55(4): 820-835
Abstract:
The spermatozoon of Siganus rivulatus is symmetrical in its longitudinal axis, has no acrosome, an almost spherical nucleus, a small mid-piece with six mitochondria, centrioles arranged at an acute angle to each other, no nuclear fossa, and a flagellum without fins. Sperm motility is reversibly inhibited in the seminal plasma, and in electrolyte and non-electrolyte solutions of 100 mosmol/kg and activated by an increase in osmotic pressure. The sperm motility parameters remain constant for 5 min after activation, then motility starts to decrease and stops 25-30 min after activation. Osmolalities between 600 and 1100 mosmol/kg and a pH between 7·5 and 9·0 do not affect the sperm motility parameters. The eggs of S. rivulatus contain several large central lipid droplets composed of neutral lipids and glycolipids. Glycogen granules and sialoglycoproteins are dispersed between the lipid droplets. The protein yolk, consisting of neutral and slightly basic proteins is located peripherally. The cortical alveoli containing neutral polysaccharids are located in the outermost regions in close vicinity to the oolemma. The chorion is two-layered and has no specialized surface structures.
(Institute for Zoology, University of Salzburg, Hellbrunnerstrasse 34, A-5020, Salzburg, Austria; Tel.: +43 662 8044 5630; fax: +43 662 8044 5698; e-mail:franz.lahnsteiner@sbg.ac.at)