Fig. 2. NLBs do not form in gut cultures from Retk- homozygous
embryos. Cultures were established from individual guts dissected from E11.5
embryos from Ret+/k- heterozygous parents. Neuron- and
glia-containing NLBs formed readily in cultures of wild-type (A,B) and
Ret+/k- (not shown) embryos but not in cultures from
Retk- homozygotes (C,D).