Development of choline acetyltransferase activity in chick cranial neural crest cells in culture

Abstract

Cultures of chick cranial neural crest cells, when grown in medium containing horse serum (HS), underwent morphological changes leading to the formation, after 6 days in culture, of dense aggregates of cells, some of which produced processes resembling neurite fascicles. In contrast, cranial neural crest cells grown under identical conditions, but with fetal calf serum (FCS) instead of HS, did not form aggregates; after 7–8 days, most of these cells were heavily pigmented. Choline acetyltransferase (CAT) activity was absent or low in freshly dissected neural tubes from embryos of stage 9 and in neural tubes in culture for 2 days in medium containing either HS or FCS. CAT activity was also absent in neural crest cells which had grown out in the presence of FCS for 6 days or in the presence of HS for 2 or 4 days. Cells grown in medium containing HS for 6 days developed significant levels of CAT activity. These results demonstrate that cranial neural crest cells in culture have the capacity to differentiate into cholinergic cells under specific conditions. When neural crest cells which had migrated from neural tubes in medium containing HS were shifted to medium containing FCS for 4 days, no CAT activity was detected. However, when neural crest cells which had migrated in medium containing FCS were shifted to medium containing HS for 4 days, the cells formed aggregates and CAT activity was present. This demonstrates that the kind of serum present in the medium did not select for the outgrowth of a specific predetermined population of neural crest cells from the neural tube, but rather that some factor associated with subsequent culture conditions influenced the cells to become cholinergic cells or pigmented cells.