We used in vitro autoradiography with [3H]glutamate to examine the distribution of glutamate recognition sites in 18 and 21 week gestation human fetal brains. We found a wide distribution of [3H]glutamate binding in both specimens, in a pattern distinct from that reported in adult brain using the same autoradiographic methods. In fetal brain, prominent [3H]glutamate binding was evident in hippo...