Serum-borne H-Y antigen in the fetal bovine freemartin.
In mammals, ovarian cells that have been exposed to soluble H-Y antigen acquire the H-Y+ cellular phenotype. They absorb H-Y antibody in serological tests. To determine whether masculinization of the bovine freemartin, the synchorial female twin of a bull, could be due to attachment of circulating bull-twin-derived H-Y in the freemartin gonad, we exposed normal fetal ovarian cells to serum from fetal bulls, fetal cows and fetal freemartins. Ovarian target cells became H-Y+ after exposure to serum from fetal bulls or fetal freemartins, but not after exposure to serum from fetal cows. In a new competitive binding radioassay, uptake of Daudi-secreted tritiated H-Y was inhibited in fetal ovarian target cells first exposed to mouse testis supernatant, a demonstrated source of soluble H-Y. It was also inhibited in ovarian target cells exposed to serum from fetal bulls or fetal freemartins; uptake was unaffected by exposure to serum from fetal cows. Since Daudi-secreted H-Y is known to induce precocious testicular organogenesis in XX indifferent gonads in culture, we infer that initial transformation of the freemartin gonad is due to H-Y antigen that is secreted in the fetal bull, transmitted in the common chorionic vasculature and bound by gonadal receptors of the fetal cow.
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D005260:Female; D005611:Freemartinism / Q000276:immunology*; D006182:H-Y Antigen; D007621:Karyotyping; D008297:Male; D010053:Ovary / Q000196:embryology / Q000276:immunology*; D011946:Receptors, Antigen / Q000378:metabolism
D006182:H-Y Antigen; D011946:Receptors, Antigen