title: Quantitation of sex chromosomal influence(s) on the somatic growth of fetal gonads in vivo.
abstract: Matings between mice carrying the heterozygous autosomal gene Steel produce 25% homozygous Sl/Sld mutants having agametic gonads composed of somatic tissue alone. Mutants show a normal 1:1 male:female sex ratio and gonadal sex corresponds to genotypic sex. Gonads from both normal and mutant male and female fetuses were obtained on a daily basis from the twelfth day of gestation to birth and morphometrically evaluated for determination of the quantitative expression of XY and XX chromosomal combinations on growth of gonadal somatic tissue. Growth of testicular soma was found to be independent of a germ cell influence throughout the entire course of gestation whereas a germ cell influence on growth of ovarian gonadal soma was apparent from day 18 and thereafter. By birth, testicular somatic growth displayed a ten-fold increase over that of the ovary. These results suggest that early gonadal somatic growth is independent of a germ cell influence. The significant impact of a Y-chromosomal influence on gonadal somatic growth may suggest that male-specific gene product(s) regulate growth as well as differentiation of the somatic elements of the fetal testis.
mesh_terms: D000818:Animals; D005260:Female; D005325:Fetal Organ Maturity; D005854:Germ Cells / Q000502:physiology; D005865:Gestational Age; D006066:Gonads / Q000002:abnormalities / Q000196:embryology*; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009929:Organ Size; D011247:Pregnancy; D012730:Sex Chromosomes