Complementary distribution of collagen type IV and the epidermal growth factor receptor in the rat embryonic telencephalon

Abstract

We previously identified an interaction between collagen type IV end the EGF receptor that regulates the differentiation of a limbic cortical phenotype in vitro (Ferri and Levitt, 1995). In the present study, we map the expression of the EGF receptor and collagen type IV in the embryonic telencephalon of the rat. At embryonic day (E) 11, the earliest age examined, both proteins are coexpressed throughout the ventricular zone in the cerebral wall; this zone remains immunoreactive throughout corticogenesis (E14-E19). The cells comprising the subventricular zone are the most intensely immunoreactive for the EGF receptor, although little collagen type IV is detected in this region. In contrast, postmitotic neurons that leave the proliferative zones are negative for the receptor. Moreover, during the peak of neuronal migration, the intermediate zone lacks collagen type IV immunoreactivity. Neurons that settle in the cortical plate once again exhibit EGF receptor immunoreactivity; this same zone is devoid of collagen type IV. By E19, coexpression of both proteins is evident only in the rostral extension of the subventricular zone, the pathway of migrating cells leading to the olfactory bulb. The temporal and spatial overlap of the EGF receptor and collagen type IV in the cortical progenitor pool in vive indicates that these molecules may participate in the initial decisions of neuronal differentiation. Their modified distribution during cortical maturation suggests a changing role for both proteins.