Fine structure of the mature spermatozoon of rhynchocinetes typus, crustacea decapoda

Abstract

Rhynchocinetes typus spermatozoa obtained from the vas deferens have the shape of a round‐headed nail. The head measures 30 μm in diameter and 14 μm of height. At the center of the flat face of the head emerges a single rigid spike of 53 μm in length. Cross sections of this spike show that it has a wall of 0.4 μm in thickness and a core of 0.6 to 0.8 μm. The outer surface of the spike has a longitudinal striation. When the spermatozoa are placed in sea water it is possible to observe the unfolding of rays. The number of rays in different spermatozoa of the same individual varies from 9 to 13. Each ray is formed by a channel‐like sheath that contains a rigid rod that occupies about 1/3 the length of the ray. This rod has a transverse striation with a periodicity of 185A. The rays are bound among them by a thin membranous sheet that is highly folded in vas deferens spermatozoa. At the distal end of each ray there is a rigid spine of 50 μm in length. The nucleus is coplanar to the radial plane and it extends through the rays. The structure and ultrastructure of R typus spermatozoa depart from that reported for spermatozoa of other Caridea species.

In vitro fertilization of the rock shrimp, Rhynchocinetes typus (Decapoda, Caridea): a review

“…All arms are coplanar and converge to a center from which a rigid spike emerges about 53 μm long (Fig. 1c, d) (Dupré and Barros, 1983;. As has been observed in the mature spermatozoa treated with the fl uorochrome Hoechst 33258, the uncondensed chromatin is contained in each arm (Fig.…”

“…1b). In mature spermatozoon, a centriole is associated with this structure (Dupré and Barros, 1983).…”

“…This type of sperm has different shapes in different groups of shrimps. The Penaeidea sperm is tack-shaped, as are those of Penaeus setiferous, Penaeus aztecus, (Clark et al, 1973;Brown et al, 1976) and Sicyonia ingentis (Clark et al, 1981a(Clark et al, , 1981bYudin et al, 1979Yudin et al, , 1980Kleve et al, 1980), while the Caridea group has sperm with a main bell-shaped body containing the chromatin and a spike in the vortex of the body, as does the sperm of Paleomon elegans (Pochon-Masson, 1969); Paleomonetes paludosus (Koheler, 1979) and Macrobrachium rosembergii (Sandifer and Lynn, 1981;Lynn and Clark, 1980, 1983a, 1983b, or an inverted umbrella shape, as in the sperm of Rhynchocinetes typus (Dupré and Barros, 1983). It has been reported that R. typus constitutes a third type of spermatozoon, an exception to the dendr obranchiata pattern , since this sperm presents a single spike like all the groups, but with 9-13 radial arms (Dupré and Barros, 1983) with actin fi laments and tubuline-like proteins (Perez et al, 1990), which is a characteristic of the pleocyemata group.…”

Role of egg surface glycoconjugate in the fertilization of the rock shrimp Rhynchocinetes typus (Milne Edwards, 1837)

“…The result obtained permit to suggest that the mechanism of the inhibition could be explained by the existence of a lectin-like molecule on the tip of the spike of the spermatozoa (the distal end of which interacts with envelope of the oocyte; Dupré & Barros, 1983, Barros et al, 1986Dupré, 1991;Ríos, 1993;Palomino, 2000;Bustamante et al, 2001) capable of recognizing the oocyte sugars, which were specifically blocked during the incubation of the sperm with the corresponding monosaccharide.…”

“…Oocytes at 5-7 days pre-molt, 1-2 days pre-molt, and 2 days post-molt were obtained by dissection from ovaries of R. typus (Dupré & Barros, 1983;Ríos, 1993), washed with filtered sea water, and fixed in 4% formaldehyde for 1-2 h for subsequent screening with lectins. Prior to fixation, some oocyte envelopes were isolated by a 15-30 min treatment with calcium-free artificial seawater containing EGTA (ASW Ca-free: NaCl 0.4 M, KCl 9 mM; MgCl 2 23 mM, MgSO 4 25 mM, NaHCO 3 2 mM, EGTA 10 mM).…”