Male reproductive physiology in a cichlid fish with biparental care: The chanchita Cichlasoma dimerus.

BIRBA AGUSTINA; RAMALLO MARTIN; LO NOSTRO FABIANA; GUIMARAES MOREIRA R; PANDOLFI MATIAS

Congreso; 10th International Symposium on Reproductive Physiology of Fish; 2014

Introduction The Southamerican cichlid fish Cichlasoma dimerus, presents a hierarchical social system, high breeding activity and biparental care of the eggs and larvae. We divided its reproductive period in 4 different phases, according to the offspring degree of development: Male with prespawning activity (MP, day 0), male with eggs (ME, day 1), male with hatched larvae (MHL, day 3), and male with swimming larvae (MSL, day 8). In order to better understand the reproductive stage, the aim of this study was to characterize males? reproductive physiology, by measuring steroid plasma levels and analyzing their testes cellular composition. Methods We calculated the gonadosomatic index (GSI), and measured the steroid plasma levels 11-ketotestosterone (11-KT), testosterone, estradiol, and the glucocorticoid cortisol, using ELISA kits. We analyzed the cellular composition of the testes by estimating the average percentage of spermatogonia type A and B, spermatocytes, spermatids, spermatozoa and interstitial tissue; 180 random points per testis were evaluated (CPCe 4.1 software), and from 4 testes of each phase 30 Leydig cells were randomly selected for the measurement of its nuclear area (Image Pro-plus software). Results and discussion MP showed 40 times more testosterone (p=0.0261) and 20 times more 11-KT (p=0.0355) plasma levels than MHL. No significant differences were observed in estradiol and cortisol levels between the different phases. The cellular composition of the testes varied along the 4 phases of reproductive period and parental care. MP?s testes were composed by a 50% of spermatozoa, showing the highest percentage (p