Journal of Neuroscience, Vol 7, 3996-4004, Copyright © 1987 by Society for Neuroscience
Catecholaminergic horizontal and amacrine cells in the ferret retina
KT Keyser, HJ Karten, B Katz and MC Bohn
Department of Neurosciences, University of California San Diego, La Jolla 92093.
Enzymes involved in the synthesis of catecholamines were detected in
amacrine and what appeared to be a specific class of horizontal cells in
the ferret retina. Antisera directed against the enzymes tyrosine
hydroxylase (TH), which converts tyrosine to DOPA, and phenylethanolamine
N-methyl-transferase (PNMT), which converts norepinephrine to epinephrine,
were used with conventional immunohistochemical techniques. A population of
perikarya located at the outer margin of the inner nuclear layer (INL)
exhibited TH-like immunoreactivity. The cell bodies were 9-12 micron in
diameter and gave rise to stout dendrites that tapered rapidly after
emergence from the somata. The processes formed a planar array in the inner
half of the outer plexiform layer (OPL) slightly external to the cells of
origin. We could not detect any inwardly directed processes. A population
of PNMT-positive cells was also observed in the outer tier of cells in the
INL. These cells were very similar to those exhibiting TH immunoreactivity.
An apparent difference between the 2 populations was that there were areas
of intense, somewhat punctate PNMT immunoreactivity in the outer OPL. These
were not observed in the TH- stained sections. Examination of horizontal
sections showed that each TH-positive cell body gave rise to 4-5 major
dendrites that branched to form a roughly circular dendritic field. In the
periphery of the retina, an individual cell's dendrites encompassed an area
up to 170 micron in diameter. The dendritic fields of cells near the center
of the retina were substantially smaller.(ABSTRACT TRUNCATED AT 250 WORDS)