Sperm‐egg interactions in the shrimp Rhynchocinetes typus

Abstract

Sperm‐egg interaction in Rhynchocinetes typus was studied with the phase‐contrast and scanning electron microscopes. R typus spermatozoa present in the vas deferens have the shape of a round‐headed nail. After contact with seawater it is possible to observe the unfolding of the rays or stellate arms, giving the spermatozoon the appearance of an inverted umbrella. From the center of the flat face of the umbrella emerges a spike with longitudinal striations. Ovarian eggs and spermatozoa were mixed in vitro by agitating them for two minutes in Millipore‐filtered seawater. The first gamete contact was established by the spermatozoon through the tip of the spike, which exerted a lytic action on the egg envelopes. After the rigid spike was completely inside the egg, the rays became aligned parallel to each other and began to enter the eggs. Toward the final stages of ray entry, it was possible to observe fusion of the ray membranes with one another, and later the fusion process continued toward the tip of the radial spines. Concomitantly, the egg surface that surrounds the sperm swelled in a circular fashion and formed a fertilization cone. After the spermatozoon entry was complete, a scarlike mark appeared at the place on the egg surface through which penetration occurred. The whole penetration process was completed within 45‐60 minutes.

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

“…3a), become aligned parallel to each other and in the same axis as the rigid spike ( Fig. 3c-e, 7a-b) (Barros et al, 1986). A similar change has been described when solubilized egg coats were placed with vas deferens sperms (Palomino, 2000;Palomino et al, 2002).…”

“…6e, 6f), which results in a perforation through which the sperm penetrates the egg coat (Barros et al, 1986). In subsequent work (Ríos and Barros, 1997) sperm extracts in polyacrylamide-gelatine gels showed proteasic activity that was completely inhibited by 0.1 mM SBTI (soybean trypsin inhibitor), and 0.1 mM pAB (p-aminobenzamidine), supporting the hypothesis that a trypsin-like enzyme is involved in sperm passage through the egg coat during fertilization.…”

“…Sperm-egg association is established between the tip of the rigid spike and the outermost chorion of the egg (Barros et al, 1986) (Fig. 3a, 3b, 3c).…”

“…3a, 3b, 3c). This binding seems to be strong because it is not disrupted by pippeting (Barros et al, 1986) Figure 1: Structure and ultrastructure of spermatozoa. A, light microscopy view of vas deferens spermatozoa.…”

“…The present study is a review of the numerous investigations about gametes and sperm-egg interaction (Barros et al, 1986;Bustamente et al, 2001;Dupré et al, 2010) of the rock shrimp R. typus, including structure (Dupré and Bellolio, 1994;Dupré and Schaaf, 1996;Cabrera, 2003;Pinto, 2003), ultrastructure of the gametes (Pérez et al, 1990;Pérez et al, 1991;Dupré and Barros, 1993;Palomino et al, 2002), the fi rst interaction (Gómez, 2002;Gómez and Dupré, 2002;Araya, 2005;Dupré et al, 2010) and fertilization Hierro, 1994;Ríos, 1997;Palomino, 2000). The results of these studies have elucidated the sequence of events during fertilization and can be extrapolated to other Caridea species.…”