Figure 3.

Myelo- and cytoarchitecture, level 3 (Interaural 8.50 mm). Series of adjacent coronal sections stained for Gallyas (A), Nissl (B) and AChE (C) and the corresponding drawing showing in black the territories of the AC and in orange the myelinic bundles schematically (D). Unambiguous nuclear boundaries are drawn with a red dashed line. The divisions of the Ce showed no difference in AChE at this level (C). The presence of heavily AChE stained I within the L, separating its subdivisions (C,D) is also distinctive in this level. Myelin fibers clearly demarcate the ventral border of the Ce and are very abundant in the B (A). Panels (E–G) are high magnification bright-field photomicrographs from Nissl-stained sections in different portions of the superficial areas of the AC (corresponding to the black squares in B); the layers are indicated in each region. In (E), the most caudal level of the Me, the MeV has lost the layered pattern and contains highly compacted cells; (F) posterior cortical nucleus (PCo) is characterized by only two layers. (G) Two of the three PAC subdivisions present at this level are shown: PAC 3 (superior) and PACs (inferior), both containing lightly stained neurons in L1. Scale: 1 mm in (A–D) and 200 μm in (E–G). The asterisk in panel B is located in L3 of PAC2, which contains more scattered Nissl-stained cells than L2.