Differentiation of smooth muscle in the genital tract of the female mouse and its temporal relation with the development of the Wolffian nerve.

The development of the smooth muscle in the genital tract of the female mouse was studied by light and electron microscopy before and after birth. These studies showed that: a) between 13 days of fetal development and 2 days after birth the cells surrounding the Mullerian duct were undifferentiated and showed a fibroblast-like appearance; b) between 3 and 10 days after birth the cells acquired several characteristics of smooth muscle but they did not seem fully mature; c) between 30 and 180 days after birth the cells acquired a mature appearance; and d) the Wolffian nerve reached the Mullerian duct surrounding tissue before the start of smooth muscle differentiation.