title: Sex differentiation of somatic tissue in the unsexualised gonad primordia of the embryos of three species of poeciliid fish.
abstract: The structure of the gonad primordia is described in the embryos of three species of poeciliid fish. Prior to the sexualisation of the germ cells, a dimorphism exists based upon the gonadal somatic features. This serves as a basis for distinguishing between male and female specimens. Presumptive males are characterised by the presence in at least one of their gonad primordia of a conspicuous stalk whereas in presumptive females, a stalk is completely lacking.
mesh_terms: D000818:Animals; D005260:Female; D005399:Fishes / Q000196:embryology*; D006066:Gonads / Q000196:embryology*; D008297:Male; D010053:Ovary / Q000196:embryology; D012733:Sex Differentiation; D013737:Testis / Q000196:embryology