ABSTRACT
Fig. 5.3 Discoglossus pictus. Early development of the acrosome and modification of the nuclear envelope in the spermatid. A, B. The dictyosomes of the Golgi apparatus give rise via Golgi vesicles to proacrosomal vesicles which fuse to form the acrosome vesicle. C, D. The acrosome vesicle collapses onto the nucleus. Nuclear pores, retract to a posterior position with accompanying diminution in width of the perinuclear cisterna After Sandoz, D. 1970a. Pp. 93-113. In B. Baccetti (eds), Comparative Spermatology, Academic Press, New York and London, Schema 1. exceptional variations, of unknown significance, even within small taxonomic groups and we will see that even the arginine content is not always high (e.g. Kasinsky 1989, 1995; Kasinsky et al. 1985). For example, Rana sperm proteins fall into Bloch's type 4 somatic-like histone category, while Xenopus and Bufo have type 3 intermediate sperm histones. The type 3 category is divisible into 2 groups: type 3B intermediate sperm histones of Bufo and intermediate type 3A sperm histones of Xenopus. Rana sperm histones are of the nucleosomal type, with a testis-specific, very lysine-rich HI histone. The sperm protein in Bufo is richer in arginine than the proteins in Xenopus. Both of these genera
contain lysine and histidine as well as arginine in their sperm proteins. Kasinsky et a l (1985) and Kasinsky (1989) indicate the types of sperm basic proteins in frogs on a phylogeny of the Anura. The existence of intrageneric variation in the composition of sperm basic protein in the Leptodactylidae has also been demonstrated for species of Physalaemus (Lopes et a l 1999), see also Taboga and Dolder (1994a) for Scinax {-Hyla) ranki.
