TRANSIENT FETAL STRUCTURE, THE GANGLIOTHALAMIC BODY, CONNECTS TELENCEPHALIC GERMINAL ZONE WITH ALL THALAMIC REGIONS IN THE DEVELOPING HUMANBRAIN

Previous studies reported that telencephalic proliferative zones contr ibute to the development of the pulvinar thalamic nucleus in the human brain (Rakic and Sidman [1969] Z. Anat. Entwicklungsgesch. 129:53-82) . The present study examined their possible contribution to the develo pment of other thalamic nuclei. Postmortem brain tissue from human fet uses ranging between 10.5 and 40 weeks of gestation (wg) was processed by Nissl staining, Golgi impregnation, and MAP2 (microtubule-associat ed protein 2) immunocytochemistry. The gangliothalamic body, suggested to serve as a conduit for cells migrating from the ganglionic eminenc e to the thalamus, was found in the period from 15 to 34 wg in all ros trocaudal thalamic regions, particularly at the level of the anterior nuclear complex, mediodorsal and pulvinar nucleus, and in addition, th e lateral geniculate nucleus. In Nissl-stained sections, the ganglioth alamic body is a thin cellular layer situated beneath the thalamic sur face, near the telencephalo-diencephalic junction. In Golgi- and MAP2- stained sections, it is a stream of mostly bipolar cells extending fro m the ganglionic eminence to the medial thalamus. In addition, MAP2-im munoreactivity confirms the neuronal nature of its cells. The present study further supports the hypothesis that certain neurons migrate fro m the ganglionic eminence to the thalamus through the transient gangli othalamic body during fetal development. Moreover, our data indicate t hat both the association (mediodorsal and pulvinar), as well as the an terior (limbic) and specific relay nuclei are potential recipients of the telencephalic neurons. (C) 1997 Wiley-Liss, Inc.