"Attachment of Follicles to the Ovarian Germinal Epithelium in Teleost Fishes"

H. GRIER; Y. WATERS; G. DE LA ROSA; F. MEIJIDE; R. NOBREGA; I. QUAGIO GRASSIOTTO; F. LO NOSTRO; L. PARENTI

Tampa,Florida, USA

Conferencia; 2005 Joint Meeting of Ichthyologists and Herpetologists; 2005

Amercian Spociety of Ichthyologists and Herpetologists

Part of our work involves the documentation of an ovarian germinal epithelium in teleost fishes and the process by which follicles are produced (folliculogenesis). By definition, a follicle consists of a single oocytes that is surrounded by follicle (granulosa) cells and is separated from the stroma by a basement membrane. This definition, which is consistent with the textbook definition for a primordial follicle, is also consistent with a follicle being wholly derived from the germinal epithelium. That is, an ovarian follicle is an epithelial derivative. In fishes whose ovarian morphology we are investigating, we consistently see that the follicle is attached to the germinal epithelium, from which it is derived. All epithelia are subtended by a supporting basement membrane. The follicle is surrounded by a basement membrane. We have observed that the basement membranes of both the follicle and the germinal epithelium merge and become one along a small part of the follicle surface, where ovulation occurs. Using light microscopy, we first observed a single basement membrane between follicles and the germinal epithelium in a goodeid, Ilyodon whitei, because basement membranes in this fish are particularly well-stained and the stromal cells are widely separated. However, subsequent observations, both with light and electron microscopy, have revealed the same morphology to be present in three perciform teleosts: in the common snook, Centropomus undecimalis (Centropomidae); in the red drum, Sciaenops ocellatus (Sciaenidae); and in juvenile Cichlasoma dimerus (Cichlidae). The attachment also occurs in Pimelodus maculatus (Pimelodidae), a basal siluriform teleost. We hypothesize that among fishes, follicles are attached to the germinal epithelium during their development, and this is where ovulation occurs.