Differential development of female embryonic gonads in temperature and hormonal sex determination: analysis of hormone receptors and aromatase expression in Caiman latirostris

CANESINI, G.; GALOPPO, GH; RAMOS, J.G.; DURANDO, M.; MUÑOZ-DE-TORO, M.; TSCHOPP, M; LUQUE, E.H.

Jornada; XVIII Jornadas Anuales Multidisciplinarias de la Sociedad Argentina de Biología (SAB); 2016

Sex determination is a process that guides bipotential gonads (undifferentiated) to develop toward testis or ovary. Caiman latirostris is a reptilian species that exhibits temperature-dependent sex determination (TSD). Also the female phenotype can be achieved after in ovo estrogen exposure; this is known as hormone-dependent sex determination (HSD). In stage 22, 24 and 27 of embryonic development (from the beginning to the end of embryonic gonadal differentiation) we assessed by IHC the expression of estrogen receptor alpha (ERα) and progesterone receptor (PR) in gonads of embryos obtained from eggs incubated at temperature producing females (TSD) or at temperature producing males plus a dose of 17β-estradiol -E2- administered at stage 20 that overrides the temperature effect and produce the female phenotype (HSD). Aromatase expression was evaluated by IHC in the ovarian clusters (previously identified by VASA) using a polyclonal antibody generated in our laboratory. HSD group showed higher expression of ERα in stage 22 while PR expression was significantly increased towards the end of embryonic development compared to TSD. In addition, we detected a specific Aromatase immunoreactivity and the expression of the enzyme was higher in the gonads of HSD females throughout development. Our results demonstrate that in caimans, embryonic female gonads obtained by temperature or hormonal sex determination exhibit different expression patterns of key molecules associated with ovarian development and function.