Nucleus limitans thalami--comparative anatomical study.

Cyto- and myeloarchitectonics as well as acetylcholinesterase activity of the nucleus limitans thalami--an important part of the nociceptive system--were studied in insectivora (Sorex araneus, Erinaceus europaeus, Talpa europaeus), rat, rabbit, cat, monkey and man. Our results suggest that nucleus limitans is phylogenetically a rather new structure. In insectivora and in the rat we could not find any evident group of neurons resembling nucleus limitans. In the rabbit and cat nucleus limitans is composed of few layers of elongated cells. In macaca and man it is a larger, more complicated structure possessing various types of neurons, and arranged into many layers.