Histological study on the oocyte filaments of the silverside Odonthestes bonariensis

Abstract

Highly developed adhesive structures are characteristic of the eggs of Odonthestes bonariensis. At spawning each egg is connected to the other ones by four to six filaments. These are extroverted only in mature eggs, about 4–5 mm long and 10μm thick, starting from coneshaped bases at the egg's surface. Histologically, no filaments are detectable during the primary growth phase of the oocytes. At the lipidic vesicle stage, rounded eosinophilic filaments appear at the cell's surface. During the following stages they increase in volume and length, running along the whole oocyte, and lose their eosinophily. The filaments are beneath the follicular cells; according to preliminary TEM observations, they derive from the zona radiata. When the oocyte is mature, the theca externa disintegrates, freeing the filaments. These rather conspicuous and complex structures are markedly different from the adhesive egg fibrils observed in other teleosts.

Fine‐scale genetic structure, estuarine colonization and incipient speciation in the marine silverside fishOdontesthes argentinensis

“…This pattern is markedly similar to the eggs of freshwater Odontesthes species (e.g. Guandalini et al . 1994).…”

“…Marine eggs have a very thick chorion and approximately 18 adhesive looped filaments attached to the surface of the egg at both ends, and three filaments attached at only one end (Phonlor & Cousin 1997). The resistant chorion protects the embryo from the effects of water dynamics, and the adhesive filaments serve primarily to attach eggs to the substrate (Guandalini et al . 1994).…”

Adhesiveness and surface patterns of eggs in neotropical freshwater teleosts

“…Besides, A. lacustris and A. britskii that are sedentary, multiple spawners, with no parental care (Bazzoli & Godinho, 1991;Lamas, 1993) showed adhesive eggs with filaments at the vegetal pole. Similar appendages occur in a large number of teleost families (Riehl & Patzner, 1998) but the long and flexible filaments found in adhesive eggs of Oryzias latipes (Temminck & Schlegel) (Hart et al, 1984) and Odonthestes bonariensis (Cuvier & Valenciennes) (Guandalini et al, 1994) are apparently different structures. The knobs at the animal pole of Acestrorhynchus spp.…”

Reproduction of landlocked Aplochiton zebra Jenyns (Pisces, Galaxiidae)

“…Other species [e.g, Oryzias latipes (Temminck and Schlegel) and Odontesthes bonariensis (Valenciennes), Iwamatsu & Keino 1978; Iwamatsu 1992; Iwamatsu et al. 1993; Guandalini et al. 1994] have an adhesive coat of filaments surrounding the eggs.…”

“…Histological analyses revealed the presence of filaments located on the chorionic surface of vitellogenic oocytes. Other species [e.g, Oryzias latipes (Temminck and Schlegel) and Odontesthes bonariensis (Valenciennes), Iwamatsu & Keino 1978;Iwamatsu 1992;Iwamatsu et al 1993;Guandalini et al 1994] have an adhesive coat of filaments surrounding the eggs. These structures serve primarily to attach the eggs to the substratum (Kuchnow & Scott 1977;Busson-Mabillot 1977).…”