XX/XY mosaicism in lymphocyte cultures from a pig with freemartin characteristics

Abstract

Extract

The freemartin condition as a cause of intersexuality in the adult pig has been suggested but never demonstrated. Hughes (1929) and Benoit (1964), both described cases of placental anastomosis between opposite sexed piglets with the formation of a freemartin-like condition in one of the foetuses. It is surprising, however, from the numerous studies over an anatomically wide range of adult pig intersexes, that none of these has shown characteristics consistent with freemartinism as described in other species. Bovine and ovine freemartins show varying degrees of intersexuality from near male in some cases to near female in others (Lillie, 1917; Bruere and McNab, 1967). In both the bovine and ovine freemartin cases cited, certain anatomical and histological features are apparently constant. These include a blind urogenital sinus, absence of a formed scrotum even in the presence of descended gonads, and characteristic sex cord formation without spermatogenic elements (Lillie, 1917). The certain diagnosis of freemartinism depends in addition, however, on the demonstration of foetal placental anastomosis having taken place between opposite sexes (Lillie, 1917). That anastomosis between placentae of opposite sexes has occurred can now be demonstrated consistently by mixed blood cell chimaerism in freemartin animals (Herschler et al., 1966; Bruere and McNab. 1967). Other non-haemopoetic tissues of the same animals have been found by the majority of investigators to be genetically female (Goodfellow et al, 1965; Gerneke 1965, 1967; Bruere, 1966; Ilbery and Williams, 1967). The occasional demonstration of chimaerism in other tissues of the freemartin (Kanagawa et al., 1965) is at present questionable. In all cases cited, the number of male (XY) cells was very low and could be explained by culture contamination with XY lymphocytes (Bruere, 1966; Gerneke, 1967).