Fig. 5.

Immunofluorescence labelling for Cx36, Cx32, and peripherin in sexually dimorphic and non-dimorphic lumbar motor nuclei in adult male rat and mouse spinal cord. (A–C) Images from rat showing rostral (A) and caudal (B) regions of the dimorphic dorsomedial nucleus (DMN), and the dorsolateral nucleus (DLN), shown in (C). Cx36-puncta are seen among clusters of peripherin-positive motoneurons (arrows), and labelling for Cx32 is seen largely in surrounding regions (arrowheads). Boxed area (B, lower box; magnified in inset of upper box, without labelling for peripherin) shows Cx32 localized to myelinated fibers passing between motoneuron dendrites. (D,E) Higher magnifications showing Cx36-puncta localized to the surface of peripherin-positive motoneurons in the dorsomedial dimorphic nucleus (D, arrows) and in a non-dimorphic motor nucleus at L4 (E, arrows), with little Cx32 (arrowheads) association at motoneurons. Cx36-puncta follow apposition of two neuronal somata (D, left arrow). (F) Images of sexually dimorphic Onuf’s nucleus in mouse, showing Cx36-puncta associated with peripherin-positive Onuf motoneurons (F1, arrows) and, in the same field, labelling for Cx32 localized to small cells among these motoneurons (F2, arrowheads). (G) Image of non-dimorphic motor nucleus from L4 of mouse, showing a similar pattern of Cx36-puncta associated with motoneurons (G1, arrows), and labelling for Cx32 at small cells (G2, arrowheads). (H,I) Triple labelling for Cx32, CNPase and peripherin in the dorsomedial dimorphic nucleus at low magnification (H), with boxed area in H magnified in (I), showing Cx32 localized to CNPase-positive oligodendrocytes (arrowheads) and not to peripherin-positive motoneurons.