The Journal of Neuroscience, August 15, 1998, 18(16):6195-6206
Growth-Related and Antennular Amputation-Induced Changes in the
Olfactory Centers of Crayfish Brain
Renate
Sandeman,
Daniel
Clarke,
David
Sandeman, and
Mark
Manly
School of Biological Science, University of New South Wales, Sydney
NSW 2052, Australia
Freshwater crayfish increase in size throughout their lives, and
this growth is accompanied by an increase in the length of the
appendages and number of mechanoreceptive and chemoreceptive sensilla
on them. We find that in the Australian freshwater crayfish Cherax destructor, neuropil volumes of the olfactory
centers increase linearly with body size over the entire size range of
animals found in their natural habitat. The number of cell somata of
two groups of interneurons associated with the olfactory centers
(projection neurons and small local neurons) also increases linearly
with the size of the animals. In contrast, axon counts of interneurons that represent a nonolfactory input to the olfactory centers show that
these reach a total number in the very early adult stages that then
remains constant regardless of the size of the animal. Only the axon
diameter of these interneurons increases linearly with body size.
Amputation of the antennule and olfactory sensilla reduces the number
of projection and local interneurons on the amputated side. No change
in the size of the olfactory centers occurs on the unamputated side.
Amputation of the olfactory receptor neurons in crayfish therefore
leads not only to a degeneration of the receptor cell endings in the
olfactory lobe but also to a trans-synaptic response in which the
number of higher order neurons decreases. Reconstitution of the
antennule and olfactory receptor neurons in small adult crayfish is
accompanied by the reestablishment of the normal number of interneurons
and neuropil volume in the olfactory centers.
Key words:
growth; olfactory centers; crayfish; turnover of
olfactory receptor cells; turnover of olfactory interneurons; TUNEL; amputation; trans-synaptic cell death; reconstitution
Copyright © 1998 Society for Neuroscience 0270-6474/98/18166195-12$05.00/0
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