COMPLEMENTARY DISTRIBUTION OF COLLAGEN TYPE-IV AND THE EPIDERMAL GROWTH-FACTOR RECEPTOR IN THE RAT EMBRYONIC TELENCEPHALON

We previously identified an interaction between collagen type IV and t he EGF receptor that regulates the differentiation of a limbic cortica l phenotype in vitro (Ferri and Levitt, 1995). In the present study, w e map the expression of the EGF receptor and collagen type IV in the e mbryonic telencephalon of the rat. At embryonic day (E) 11, the earlie st age examined, both proteins are coexpressed throughout the ventricu lar zone in the cerebral wall; this zone remains immunoreactive throug hout corticogenesis (E14-E19), The cells comprising the subventricular zone are the most intensely immunoreactive for the EGF receptor, alth ough little collagen type IV is detected in this region. In contrast, postmitotic neurons that leave the proliferative zones are negative fo r the receptor. Moreover, during the peak of neuronal migration, the i ntermediate zone lacks collagen type IV immunoreactivity. Neurons that settle in the cortical plate once again exhibit EGF receptor immunore activity; this same zone is devoid of collagen type IV. By E19, coexpr ession of both proteins is evident only in the rostral extension of th e subventricular zone, the pathway of migrating cells leading to the o lfactory bulb. The temporal and spatial overlap of the EGF receptor an d collagen type IV in the cortical progenitor pool in vivo indicates t hat these molecules may participate in the initial decisions of neuron al differentiation. Their modified distribution during cortical matura tion suggests a changing role for both proteins.