EXPRESSION OF N-CADHERIN MESSENGER-RNA DURING DEVELOPMENT OF THE MOUSE-BRAIN

The expression of N-cadherin mRNA was mapped in the brain of mice betw een embryonic day 12 (E12) and the adult stage by in situ hybridizatio n of digoxigenin-labeled riboprobe. Two phases of N-cadherin expressio n can be distinguished. During the first phase (about E12 to E16), exp ression is ubiquitous throughout the brain and most prominent in the p roliferative neuroepithelium. During the second phase (about E16 to po stnatal day 6), N-cadherin expression is restricted to particular nucl ei or laminae that share common functional features and neuroanatomica l connections. Several of the N-cadherin-positive structures receive d irect afferents from retinal ganglion cells or from the superior colli culus. Others belong to the reticular system and to the limbic system of the brain. In neocortex, N-cadherin is expressed by deeper layer ce lls. In the adult brain, only low levels of N-cadherin expression rema in in very few types of cells, for example in the Purkinje cells of th e cerebellum. These results are similar to data from chicken brain and suggest that the generalized expression of N-cadherin during the earl y phase and the restriction expression of this molecule in particular functional systems during the later phase is, at least in part, phylog enetically conserved between chicken and mouse. Moreover, the results show that N-cadherin expression extends to phylogenetically newer stru ctures, e.g., the mammalian neocortex. (C) 1993 Wiley-Liss, Inc.