Behavior of Pigment Cells from Cultures of Neural Crest When Grafted Back into the Embryo. ∗

Neural crest taken from chick embryos in early somite stages produces large numbers of pigment cells both in vitro, 1 and in grafts to the limb buds of older host embryos, the melanophores later appearing in the dermis and feathers of the hosts. 2 This work has been corroborated by Eastlick, 3 who transplanted limb buds with or without the neural crest, and found that the appearance of pigment was correlated with the presence of the neural component in the grafts.

The earlier cultures were short time cover slip preparations designed to test the capacity for differentiation of the tissue explanted. In view of the complex prospective potency of the neural crest in the embryo, it seemed advisable to attempt to develop pure cell strains in order to study the behavior of these cells under controlled conditions. For the past year, explants of early somite neural crest from colored breeds have been grown in small culture flasks in a standard medium of plasma and embryonic extract, according to the technic developed by Carrel and his associates. Such cultures grow rapidly during the first week in vitro, soon producing a ring of dark brown or black cells. Growth then continues at a slower rate, and strains of cells are produced which are uniform in appearance and behavior, being composed of typical branched melanophores which spread out upon the clot or become aggregated in clumps.

Cells from these cultures have been grafted to embryos of another breed than that of the donor, a single culture furnishing enough tissue to graft to as many as 30 host embryos, without entirely exhausting the original strain. When a graft is inserted into the limb bud of a white host (which is subsequently observed through a transparent window in the shell), the ectoderm heals over the tissue, which is still clearly visible as a dark mass below the surface.