Fig. 2. Survival of cranial and trunk neural crest cell cultures is differentially affected by secreted factors. Bright-field photograph of cranial neural crest culture treated with recombinant FGF2 protein for 36 hours reveals migrating cells (A). The same culture stained with DAPI to reveal nuclei (B) and with anti-p75 nerve growth factor (NGF) receptor antibody that recognizes neural crest cells (C). A histogram of survival rates for cranial and trunk neural crest cells cultures shows that the cranial and trunk neural crest cell cultures had different survival rates under similar culture conditions (t-test: P<0.001, except for TGFß1 for which P<0.03) (D). % survival=(number of cultures after 7 days in culture/number of explants displaying cell outgrowth on 1st day)x100. (E-G) Apoptosis is not detected in 48 hour cranial neural crest cultures treated with FGF2 (E), whereas many cranial neural crest cells treated with BMP2 for 18 hours (F) and 36 hours (G) undergo cell death as detected with TUNEL and HRP-conjugated antibody.