Neuronal birth and neurite outgrowth have been regarded as discrete, s
equential stages of development. However, we recently found that sympa
thetic neuroblasts often elaborate axons before mitosis, in culture [E
. Wolf, I.B. Black, E. DiCicco-Bloom, Mitotic neuroblasts determine ne
uritic patterning of progeny, J. Comp. Neurol. 367 (1996) 623-635] and
in vivo [E. Wolf, I.B, Black, E. DiCicco-Bloom, Central and periphera
l neuroblasts elaborate neurites prior to division in vivo and in vitr
o, Soc. Neurosci. Abstr. 21 (1995) 785; E. Wolf, I.B. Black, E. DiCicc
o-Bloom, Mitotic neuroblasts engage in axonal outgrowth and pathfindin
g in vivo, Sec. Neurosci. Abstr. 22 (1996) 525]. Here, we report that
cerebellar granule cells often divide with heritable neurites in vitro
. Therefore, mitotic CNS precursors, in addition to peripheral neurobl
asts, simultaneously undergo proliferation and process formation. Pote
ntially, neurites on dividing precursors may allow target fields to in
fluence directly the course of neurogenesis. (C) 1997 Elsevier Science
B.V.