Biplexiform ganglion cells in the retina of the perciform fish Pholidapus dybowskii revealed by HRP labeling from the optic nerve and optic tectum.

Using retrograde HRP labeling from the optic nerve (ON) or optic tectum (OT), we have visualized biplexiform cells in wholemounted retinas of the stichaeid fish Pholidapus dybowskii and studied their morphology and spatial properties. Biplexiform cells labeled from the ON were similar in their morphology to biplexiform cells found in other fishes. Their distribution across the retina was non-random and independent of that of other large ganglion cell types. Biplexiform cells labeled from the OT, too, formed non-random mosaics, whose spatial properties suggested that most or all biplexiform cells project to the OT in this species. We propose that biplexiform cells in Pholidapus are homologous to biplexiform cells in other fishes (lower vertebrates). Pholidapus biplexiform cells may participate in the tectum-mediated visual reactions.