OLFACTORY-BULB TRANSPLANTS ESTABLISH AFFERENT AND EFFERENT CONNECTIONS WITH HOST FOREBRAIN IN RAT

We are using wheat germ agglutinin-conjugated horseradish peroxidase ( WHRP) to study reeonnectivity in the transplanted (TX) olfactory bulb (OB) in Sprague-Dawley rats. Tritium-labeled OBs from fetal rat donors of Embryonic Days 14-15 were immediately grafted into neonatal rats i n the site from which the host OB had been removed. Following survival times of 7 weeks and longer, WHRP solution was injected into the TX O B, and subjects were perfused after 24 h. The WHRP transport is seen i n fibers from the TX OB into layer I of the host olfactory peduncle (O F) and olfactory cortex (OC) and in cell bodies in layers II and III o f the OP and OC, the lateral hypothalamus, and the contralateral anter ior olfactory nucleus (AON). These findings reaffirm that the axons fr om a TX OB make connections with some appropriate areas of the host br ain and also indicate that axons from cells in the target areas of the host brain, including contralateral AON, reinnervate the TX OB. (C) 1 995 Academic Press, Inc.