Fig. 2. Th-positive neurons in the mesencephalon at embryonic stages E11.5 to E14.5. (A) Coronal sections from the posterior to anterior mesencephalon. (B) Enlargement of sections displaying the aberrant development in the SNc region (arrow) at stage E12.5 and E14.5. The arrows indicate the anatomical positions where mesDA neurons are missing. The asterisk indicates the medial position where mesDA neurons are ectopically present in the ak.