The fate of the grafted quail Mullerian duct in the chick embryonic coelom.

Recent morphological analyses of Mullerian duct regression suggested that some ductal cells might survive, in contrast to the previous view that regression was an example of "programmed cell death." The present study was designed to demonstrate survival of Mullerian duct cells after regression, and to map migration into local or distant tissues. Seven or eight-day-old chick embryos received intraabdominal grafts of Mullerian ducts from seven- or eight-day-old quails, creating chick-quail chimeras. Three or four days later the abdomen was serially sectioned and examined histologically using a modified Feulgen stain. Sixty-six of the 230 grafted embryos survived (29%). After sectioning, grafts were found in 34 of the 58 embryos in the body wall, peritoneum or mesenephros, with several adherent to the hosts' Mullerian ducts. Twenty female embryos contained grafts, all of which were developing normally. Fourteen male embryos contained grafts in various stages of regression. Regression was more advanced in mesonephric or body wall grafts while free intraperitoneal grafts showed the least regression. Migration of quail cells was striking when seen in grafts placed in the mesonephros or adherent to the host Mullerian duct. In these, regressing quail cells migrated into and became incorporated in adjacent chick mesenephros. Migration patterns were seen also in non-regressing cells in female hosts, where quail cells "homed" to the host chick Mullerian duct structures.