El sistema de la hormona liberadora de gonadotrofinas (GnRH) en el pez cíclido Cichlasoma dimerus: localización anatómica, ontogenia y su relación con la diferenciación gonadal.

M. PANDOLFI, M. RAVAGLIA, F. MEIJIDE, C. MAGGESE Y D. PAZ

Tafí del Valle, Argentina

Congreso; XIX Jornadas Científicas de la Sociedad de Biología de Tucumán; 2002

Sociedad de Biología de Tucumán

The distribution and ontogeny of 3 distinct gonadotropin-releasing hormone (GnRH) neural systems in the cichlid fish Cichlasoma dimerus have been described. In the forebrain a group of neurones immunoreactive (ir-) to salmon GnRH were detected by day 3 after fertilization in the olfactory placodes. These neurons were seen along the olfactory nerves and in the olfactory bulb by day 4 and at the nucleus olfacto retinalis (NOR) on day 10. A group of neurones ir-chicken GnRH II were seen in the dorsal midbrain tegmentum (MB) originating from the ventricular ependyma on day 5. Between days 22 and 30, neurones ir-seabream GnRH were detected in the anterior basal preoptic area. GnRH innervation of the pituitary was detected after the differentiation of preoptic neurones in coincidence with gonadal differentiation. We conclude that the GnRH neural systems have three distinct embryonic origins. We also hypothesize that the NOR and MB GnRH neurones might have functions other than gonadal development. Preoptic GnRH neurones in C. dimerus might be associated with gonadal sex differentiation