Restroation of the capacity to form pole cells in u.v.-irradiated Drosophila embryos.

Injection of pole plasm into u.v.-irradiated posterior poles of early Drosophila embryos leads to the restoration of the capacity to form pole cells in nearly half of the recipients. The effect is specific, since cytoplasm from the anterior tip has no such result. In most cases only a small number (between 1 and 5) of discrete pole cells are formed. However, a large number of pole cell fragments with or without nuclei occur. Occasionally pole cells were formed outside the area of the originally irradiated pole plasm. This happened when material was injected more anteriorly than usual. Thus polar cytoplasm contains some factor(s) necessary for the formation of pole cells.