Fig. 7.

Topographic distribution of MIF motoneurons. (A) Drawings of alternate coronal sections of the abducens nucleus from caudal (Top) to rostral (Bottom) of the three animals injected with Rho into the lateral rectus myotendinous junction to label MIF motoneurons (red dots). d, dorsal; v, ventral. (B and C) Images of the abducens nucleus after ChAT immunostaining (green) and retrograde Rho injection (Rho, red). Doubly labeled cells (ChAT⁺ and Rho⁺) correspond to MIF motoneurons (arrows). The dashed lines delineate the facial genu. These two images correspond to the drawings indicated in A as B and C for cat # 2. At the top of each of the three series the muscle injection for each cat is shown. (D) Graph showing the location of MIF motoneurons (colored dots) through the abducens nucleus in the three orthogonal axis (C-R, caudo-rostral; D-V, dorso-ventral; and M-L, medio-lateral) taking the most rostral point of the brainstem midline as the zero of coordinates. Eight colors were used to represent the location of MIF motoneurons; each color corresponds to each of the eight drawings shown for cat # 2 in A. (E–G) Planar representations of the graph shown in D. In F (same orientation as drawings in A), the limits of the abducens nucleus are indicated. (Scale bar, 200 µm for B and C.)