REGIONAL DIFFERENCES IN IN-VITRO GROWTH OF NEURAL CELL PROCESSES DURING DEVELOPMENT

Primary cell cultures from cerebral cortex, striatum and ventral mesen cephalon obtained from rat fetal (embryonic day 17, E17) or postnatal (day 2, PN2) donors were grown either in media conditioned by subcultu red astroglia from the same regions, an artificial trophic medium, nor mal human amniotic fluid, or in normal human cerebrospinal fluid. To e stimate the presence of neuronal-like and non-neuronal cells, cell mor phology and immunocytochemistry against microtubule-associated protein s and beta-tubulin were taken into consideration. The percentage of em itting neural cells and length of cell processes were determined after 24 hr in culture; Growth of cell,recesses in neuronal and non-neurona l cells from prenatal striatum was minimal compared with that in cereb ral cortex and ventral mesencephalon, regardless of the culture condit ion. Nerve growth factor, basic fibroblast growth factor or epidermal growth factor did not significantly modify cell growth in E17 cultures , except for epidermal growth factor, which reduced the number of emit ting cells in striatal cultures and increased it in cerebral cortex on es. Cultures derived from postnatal striatum showed a significant incr ease in neurite length when grown in an astroglial conditioned medium as compared to cultures derived from prenatal(E17) striatum. Results s uggest significant regional differences in the brain regarding growth of cell processes at age E17, and reversal of striatal ability to grow cell processes by postnatal day 2. Reduced growth of cell processes s howed by E17 striatum cultures was rather independent of the culture m edia. This fact could suggest that such early regional differences wou ld depend on characteristics of sublineages present at this developmen tal stage, which would modulate the organization of regional neuropils . The restricted growth of cell processes in cultures from E17 striatu m, no longer present in postnatal striatum, suggests that inputs to th e striatum may modify expression of cell lineages at later stages of d evelopment. Copyright (C) 1996 ISDN.