engleski

Nonradial migratory stream from cortical hem during early fetal period in primates

Cortical hem, a putative signaling centre at the interface of the prospective hippocampus and the choroid plexus, is a significant source of Cajal-Retzius cell population that invade cortical marginal zone. Analyzing Nissl stained sections of human fetuses during the period from 8 to 14 postconceptional weeks (pcw), we observed, in the medial telencephalic wall, a stream of cells extending from the proliferative zones of cortical hem to the marginal zone (MZ) of the prospective archicortex. Golgi staining showed that this stream is composed of small unipolar migratory like cells. At corresponding ages in the macaque monkey fetuses (embryonic day/E 47-55), many cells in the proliferative zones of cortical hem were labeled for calbindin (CB). From this zone, a stream of unipolar migratory like CB-containing cells extended to the subpial position. In addition, at E47 few CB-containing neurons were observed in the thick MZ of the prospective archicortex. They were in apparent continuity with the stream of migratory like CB-containing cells extending from proliferative zone of cortical hem. At E55, CB-containing cells in the prospective hippocampus were organized in clusters. The clusters of CB-containing cells close to the proliferative zones were formed of immature cells, while more distant clusters included cells with typical pyramidal neuron body shape. During this period, GAD-containing migrating cells were mostly observed in the lateral wall, only very few were present in the medial telencephalic wall. Therefore, our results suggest that in primates the cortical hem gives rise to populations of non-GABA-ergic calbindin neurons, some of them destined to the hippocampus.

cortical hem; GABA; GAD; calbindin; Cajal-Retzius; hippocampus

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