Fig. 1. Formation of NLBs in cultures of dissociated foetal and postnatal gut. Whole gut from E11.5 mouse embryos (A-E) or the outer muscle layers from P2-14 gut (F-J) were dissociated and plated in NCSC medium. 2-3 days later characteristic colonies appeared in both foetal and postnatal gut cultures (A and F, respectively) which were composed of flat cells with small processes. Higher magnification of individual cells is shown in the insets. Over the next 3-4 days colonies grew in size (B,G) and eventually formed NLBs which detached and floated in the medium by day 10 (C,H). Immunostaining with antibodies against TuJ1 and GFAP indicated that NLBs from both foetal (D,E) and postnatal (I,J) cultures contained large numbers of neurons and glia. E and J are enlargements of parts of the NLBs shown in D and I, respectively. Note that postnatal NLBs were reproducibly smaller relative to their foetal counterparts.