Experimental Sex Inversion of Chicken Embryos at Aromatase Inhibition, Estrogen Receptor Modulation, DNA Demethylation and Progesterone Treatment

Abstract

The work was carried out by microinjections of an aromatase inhibitor letrozole, an estrogen receptor modulator tamoxifen in incubated eggs Gallus g. domesticus , the first day of incubation. It also used 5-azacytidine (5-AC) at the same time. Injection of progesterone was carried out before the onset of meiosis prophase 1 on 16 h of incubation. Morphologically and histologically and by PCR, sex of the 17-day embryos was controlled. According to information received microinjection of letrozole caused almost a 100% inversion of genetic males to females, which is manifested in the morphology of the gonads. In other experiments, sex reversal is not revealed. The results are obtained in this study, and the data suggest that the presence of gonadogenesis in female chickens makes earlier emergence of aromatase in the beginning of incubation, than that according to the classical scheme of sex determination in birds. Presumably this kind of synthesis is triggered by some W-chromosomal factors. It failed to detect the phenomenon of gender inversion—the transformation of males into females after exposure to demethylating agent 5-AC that casts doubt on the participation of male hypermethylated (MHM)-RNA-segment in regulating the activity of sex determining genes.