Distribution of expression of cell adhesion molecules in the mid to late gestational mouse fetus

The control of murine morphogenesis appears to be regulated in part by the expression of the primary cell adhesion molecules, such as the neural cell adhesion molecules (N-CAM). Here we show that the epithelial cell adhesion molecules appear in intestinal epithelium, liver and cartilage, but were absent from intestinal submucosa and neural tissues. N-CAMs on the other hand were present in intestinal submucosa and neural tissues, but absent from intestinal epithelium, liver, and cartilage. Both epithelial cell adhesion molecules and N-CAM were present in intestinal primordium at gestation times (days 12 and 13) when intestinal epithelium and submucosa are not morphologically distinguishable. On day 14 of gestation, when the intestinal epithelium and submucosa are morphologically distinguishable, epithelial cell adhesion molecules are present in intestinal epithelium but not submucosa while N-CAM has the reciprocal pattern of expression. Immunoblots with antibodies to N-CAM revealed two bands of 110-220 and 60 kD which followed specific patterns of expression. As defined by densitometry, the intensity of the larger protein increased from day 12 to 18 in neural tissue groups, but diminished in late gestational intestine and intact fetus and was replaced by a more discrete region of 110-150 kD, suggesting that embryonic to adult conversion of isoform ('E to A conversion') had occurred at this nonneural site.