Influence of the hypogonadism ( hgn) locus on female reproduction and ovarian development in an altered genetic background

Abstract

Background and Aims:  The hypogonadic rat ( hgn/hgn) shows male sterility controlled by a single recessive gene hgn. The hgn/hgn females detected by the presence of renal hypoplasia in the HGN inbred strain show a reduced fertility. Recently, the gene responsible for male hypogonadism was mapped on chromosome 10 by a linkage analysis using only male backcross progeny. Because backcross females could not be categorized as affected or normal because of variations in their renal sizes, we could not examine female fertility in the backcross progeny. In the present experiment, we examined whether the gene mapped on rat chromosome 10 has any influences on female reproduction and ovarian development.

Methods:  The assumptive hgn/hgn females were identified in the backcross progeny by microsatellite markers closely linked to the hgn locus. Postnatal body growth, the weights of reproductive organs, estrus cycle and ovarian histology were examined. In addition, backcross embryos were genotyped, and their body growth and ovarian development was examined.

Results:  The hgn/hgn females showed growth retardation, a short reproductive life and an abnormal ovarian histology as adults. Regarding embryonic development, hgn/hgn females showed body growth retardation and ovarian hypoplasia.

Conclusion:  The mutation of the hgn mapped on chromosome 10 causes not only male sterility but also female reduced fertility related to ovarian hypoplasia beyond the altered genetic background. (Reprod Med Biol 2006; 5: 227–234)