A choroid tapetum lucidum that is made of a palisade of cells containing stacks of flat hexagonal crystals of guanine. [ https://orcid.org/0000-0002-6601-2165 http://www.ncbi.nlm.nih.gov/pubmed/14738502 http://en.wikipedia.org/wiki/Tapetum_lucidum#Classification ]
Term information
http://purl.obolibrary.org/obo/NCBITaxon_7778
http://purl.obolibrary.org/obo/NCBITaxon_7864
A choroidal tapetum of reflecting cells lying immediately outside the choriocapillaris is formed in a few primitive teleosts.
elasmobranchii (skates, rays, and sharks) and chimaeras
The elasmobranch tapetum in Squalus and Scyliorhinus con- sists of sheets of 12-13 superposed guanine crystals in the choroid.