[Ultrastructure of the "rudimentary secretory photoreceptors" (RSP) of the embryonic pineal body of Lacerta vivipara J. (Reptilia, Lacertilia) and the origin of the RSP of Sauropsida].

The "secretory rudimentary photoreceptor-cells" of Lacerta vivipara J., during embryonic stages, exhibit photosensory differentiations (disks). Our ontogenetic observations agree with the phylogenetic studies and support the concept of a "sensory cell line" (Colin, 1969) in the pineal organ of vertebrates.