Connexin mRNA expression in postnatal hippocampal neurospheres cultured in the absence of exogenous ECM. RT-PCR analysis of Cx26 (a), Cx29 (b), Cx30 (c), Cx32 (d), Cx36 (e), Cx37 (f), Cx40 (g), Cx43 (h), Cx45 (i), and Cx47 (j) of random-primed RNA extracted from 100–150 pooled neurosphere cultures (+RT). GAPDH was amplified to confirm template integrity. Positive controls were: Total RNA isolated from adult and/or P1 WT whole brain. Negative controls included RT-PCR reactions performed on total RNA from null-mutant neurospheres (Cx29-/-, Cx30-/-, and Cx45-/-) or adult brain (Cx32-/Y, Cx36-/-, Cx40-/-, Cx37-/-, and Cx47-/-), and reactions processed in the absence of template (NT). Potential contamination by genomic DNA was assessed by omitting the RT enzyme from the reactions (-RT). In a, c, and e, panels depict neurosphere cryosections derived from Cx29-/-, Cx30-/-, and Cx36-/- animals processed for β-galactosidase immunocytochemistry. The LacZ gene replaces the connexin coding sequence in each of these null-mutant animals. Insets are antibody controls demonstrating WT sections are negative for the β-galactosidase marker. Scale bars, 50 μm.