Cell death in the normal development of Gallotia galloti mesencephalon (Reptilia Lacertidae). An ultrastructural study.

We have studied the development of the mesencephalon of Gallotia galloti and we have observed two classes of cellular death: 'nuclear' or 'Type I' and 'cytoplasmatic' or 'Type II'. The first appears in stages around E-34 and the second one is observed from stages around hatching to the adult lizard. The degenerative cells have been observed in the profundus, torus semicircularis, the 5th pair of the trigeminal nerve nuclei as well as the 4th and 5th layers of the optic tectum where this last nucleus mentioned is situated.