Spontaneous and XXXX -induced @entity21161 in @entity19 .

@entity1 @entity39 @entity19 @entity5767 @entity21161 @entity13258 @entity1968
A spontaneous @entity21161 , similar to type B in @entity1 , was found in a partially inbred ICR @entity19 . The supernumerary digit could be detected grossly as early as day 14 of gestation. The incidence of @entity5767 decreased with increasing gestational age. @entity1968 (RA) administered on day 10 or 11 of gestation, but not on day 9, increased the incidence of @entity5767 at each gestational day examined. The day 18 levels of @entity5767 were greatest after day 10 treatment. No clear dose-response relationship was observed in term fetuses following treatment on day 9, 10, or 11. RA administered on day 10 produced extra digits which were morphologically more advanced than those in the untreated controls. RA, given to the inbred C57B1/10 strain, produced low levels of @entity5767 if administered on day 9, but not on day 10 or 11. F1 embryos, from reciprocal crosses between the two strains, were intermediate in response to RA. On day 14, cell death in the postaxial marginal mesoderm was apparent in all protopolydactylous embryos examined, whether treated or untreated. The @entity13258 varied in size on day 14. The smaller digits appeared to be filled with @entity39 mesodermal cells, whereas the larger digits had a @entity39 -free area. The size of the extra digit on day 14 seemed to be the most important factor in the persistence of the digit until day 18.
