Marrow Chimerism in Marmosets

Abstract
In the femoral marrow of three adult marmosets, two male Callithrix jacchus and one female Leontocebus rosalia, a number of opposite-sexed metaphases were found. It is inferred that this chimeric state resulted from intrauterine placental anastomoses between heterosexual twins. The lack of the freemartin effect in connection with this chimerism is discussed, and the structural nature of the Y chromosome in the Callithricidae is described.