Abstract
from my Masters Thesis:
Morphological Distribution and
Behavioral Outputs of Type I Antennular Withdrawal Interneurons in the
Blue Crab, Callinectes sapidus
Biocytin (4%, Sigma) was iontophoretically injected into single identified
antenna I withdrawal interneurons (IN’s 20-23) to determine their morphological
distribution in the brain of the crab, Callinectes sapidus. Dissected
brains containing biocytin-filled IN’s were fixed for light microscopy,
embedded in gelatin, and sectioned at 100 µm. The sections
were reacted with Vectastain Elite ABC reagent (Vector Labs) in 0.3% Triton-X
100 and then treated with 3,3-diaminobenzidine. Biocytin was found to infiltrate
small neurites in these cells more effectively than the fluorescent marker
Lucifer Yellow (Molecular Probes) or Neurobiotin (Vector Labs). The
somata of these morphologically similar cells were found in the anterior
cluster and each sent a primary neurite down the contralateral esophageal
connective. Type I IN’s possessed thick secondary neurites that branched
in the ipsilateral lateral antenna I neuropil (LAN), the median antenna
I neuropil (MAN) bilaterally, the ipsilateral tegumentary neuropil (TN)
and the ipsilateral antenna II neuropil (AnN). Two of these cells
(IN21 and IN23) sent thick, secondary neurites bilaterally into both LAN’s.
Cells were identified on the basis of differences in the morphology and
distribution of secondary neurites. Physiological data showed that
all Type I IN’s produce withdrawal of the ipsilateral antenna I.
Intracellular depolarization of IN23 also produced powerful withdrawal
of the ipsilateral antenna II. All Type I IN’s produced weaker, delayed
withdrawal of the contralateral ANT I.
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Copyright 1998. Christopher Michael Kilroy