A Microscopic Study on the Egg Envelope of an Endemic Korean Fish, Coreoleuciscus splendidus, Cyprinidae, Teleostei

Architectures in the egg surface of various teleosts play an important role in evaluating their eggs properties as follows: the attachment of the eggs to the substratum in stream bed, and sticks or debris; the retention of water or pressure; the protection of embryo; the chorionic respiratory system; the process of water hardening (Blaxter, 1969; Wourms & Sheldon, 1976; Erickson & Pikitch, 1993; Riehl & Patzner, 1998). In addition, it has been noted that the morphological differences of the adhesive material and the associated inner layers could be a useful aid in the identification of eggs from different taxa of fish (Johnson & Werner, 1986) and as well as assist in determining the phylogenetic relationships between species (Laale, 1980; Groot & Alderdice, 1985; Riehl & Greven, 1993; Park et al., 2001; Park & Kim, 2001, 2003; Kim & Park, 2014). The Korean dace Coreoleuciscus splendidus, belonging to the subfamily Gobioninae in the family Cyprinidae, is an endemic freshwater fish in the Korean Peninsula (Kim & Park, 2002). The fish inhabits the bottom of running waters with moderately fast currents (0.4~1.3 m s) and shallow waters about 0.3~0.5 m deep in the upper and middle regions (Kim & Park, 2002). For C. splendidus, however, there was no information on fine structures in detail and development of egg envelope (zona radiata=egg surface=oocyte envelope= adhesive structure) covering the oocyte in this species. Therefore, the purpose of the present study is to describe the developmental features and the fine structures of the oocyte envelopes, and the relationship between their habitats and the egg envelopes in C. splendidus.