Journal of Neuroscience, Vol 10, 848-859, Copyright © 1990 by Society for Neuroscience
Insect olfactory neurons in vitro: morphological and physiological characterization of cells from the developing antennal lobes of Manduca sexta
JH Hayashi and JG Hildebrand
Arizona Research Laboratories, University of Arizona, Tucson 85721.
To facilitate studies of the development and membrane biophysics of cells
in the central olfactory pathway of the moth Manduca sexta, we have
dissociated neurons and glial cells from the antennal lobes (ALs) and
cultivated them in the controlled environment of tissue culture. Cultures
produced from cells of the lateral group of AL neurons alone are enriched
in local interneurons (LNs), while cultures made from cells of the median
and anterior groups of AL neurons contain projection neurons (PNs) but lack
LNs. Cultures containing only PNs, but not cultures with both PNs and LNs,
require a conditioning factor derived from a conspecific cell line in order
to ensure survival. Under these conditions, we identify 5 types of cells in
the "PN-only" cultures that are consistently observed and distinguishable
on the basis of their morphology and characteristic whole-cell current
profiles. In cultures that contain both PNs and LNs, we find 3 additional
types of cells with neuronlike appearance. Whereas the PNs have whole-cell
currents that suggest a neuronal phenotype, we have not yet observed
similar currents in the 3 other types of cells. We tentatively identify the
latter 3 cell types as LNs whose development has been arrested. The
conditioning factor also has a trophic effect on phase-dark, multipolar
cells that are observed in freshly dispersed cultures. Their morphology and
whole-cell currents lead us to suggest that they are glial cells.