Scanning electron microscopy of the chorion of selected freshwater fishes

Abstract

The external morphology of the chorion of five species of freshwater fish (AlosapseudoharenRus. Oncorhynchus kisutch. Osmerus mordax, Esox masyuinongy, and Stizostedion vitreum) were studied using scanning electron microscopy. Electron micrographs and descriptions of the five species are presented. The results suggest that the surfaces are sufficiently distinct to allow for differentiation based on surface architecture at the ultrastructural level.

Ultrastructural studies of the morphological variations of the egg surface and envelopes of the African catfish <em>Clarias gariepinus</em> (Burchell, 1822) before and after fertilisation with a discussion of fertilisation mechanism

“…Further changes were recorded at the 30 h stage (Fig.5E). Similar ornamentation patterns have been recorded by many authors working on different teleost species belonging to different taxonomic groups (Johnson and Werner, 1986;Cotelli et al, 1988;Merrett and Barnes, 1996;Chen et al, 1999;Rizzo et al, 2002;Chiou et al, 2004). Some of these authors considered the egg surface ornamentation as taxonomic characters at the specific level.…”

“…4E). The debris-like dots and the partially reticulated debris might represent the poorly preserved remains of the diffuse mucus layer (Lönning and Hagstrom, 1975;Johnson and Werner, 1986). The ornamentation varied from the germinal disc region to the vegetal hemisphere (Fig.…”

Ultrastructural features of the egg envelope of silver carp, Hypophthalmichthys molitrix (Osteichthyes, Cyprinidae)

“…As to the thickness of the membrane, although there could be differences among different kinds of fishes, these might be affected by ecological environments and developmental stages (Ivankov & Kurdyayeva 1973, Riehl 1978. The chorion surface has also been analyzed using scanning electron microscopy by Johnson & Werner (1986), who described the external morphology of the chorion of five freshwater fishes and concluded that scanning electron microscopy was a powerful tool for identifying fish eggs. On the other hand, the micropyle plays an important role in gamete recognition during fertilization, so its morphology may be species specific (Ginzburg 1968, Kobayashi & Yamamoto 1981.…”

Fine structures of oocyte envelopes of three related cobitid species in the genus Iksookimia (Cobitidae)

“…In addition, the morphological aspects of the envelope have been used for the identification of eggs from different taxa (Johnson and Werner, 1986) and a useful aid in determining the phylogenetic relationships (Laale, 1980;Groot and Alderdice, 1985;Riehl and Greven, 1993;Britz et al, 1995;Park and Kim, 1997;Thiaw and Mattei, 1996). It has been reported that the function of the egg envelope is for the attachment of the eggs to the substratum in a stream bed and the retention of water or pressure, or protection of the embryo (Blaxter, 1969;Laale, 1980;Groot and Alderdice, 1985;Riehl and Greven, 1990;Erickson and Pikitch, 1993;Thiaw and Mattei, 1996;Riehl and Patzner, 1998).…”