Springer Online Journal Archives 1860-2000
Summary Early ontogenetic events in the brain of a lizard, Lacerta sicula, were investigated by means of H3-thymidine autoradiography. Varying dynamic properties—beginning, duration, and end of the proliferating activity, dynamics of the generation cycle—of the matrix zones of different regions and areas of the brain were observed. The main interest was focused on the rhombencephalon, where a distinct heterochronism of proliferation was described for different systems and nuclear groups. Eye muscle nuclei, the trigeminal system, and the hypoglossal nucleus arrive earliest (stage day 1/2–1 1/2). The vestibular and the cochlear system cease their proliferation at stage day 2 1/2 and stage day 3 1/2 respectively. Their proliferation is very rapid. In contrast, the sensory regions of the VIIth, IXth, and Xth nerves and the tegmental regions show a slow, long-lasting proliferation. The great difficulties for embryologic and experimental approach in reptiles are discussed.
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