Dorsal root afferents to clarke's column from hindlimb cord levels in Tupaia and Galago.

The projection of hindlimb dorsal root afferents to Clarke's column has been studied in the tree shrew (Tupaia glis) and lesser bushbaby (Galago senegalensis). In the bushbaby, fibers from K12, L1 and L3 projected ipsilaterally to Clark's nucleus from levels L3 to T3, L2 to T4 and L3 to T5 respectively. In Tupaia, afferents from T11, L1, and L3 terminated ipsilaterally within the nucleus from segments L2 to T4, L3 to T6, and L3 to T8. Fibers from T12, L1, and L3 in Galago and T11 in Tupaia terminated within the even to lateral aspect of the nucleus at lower levels, throughout the nucleus at middle levels and in the dorsal aspect of the column at rostral levels. Fibers from T11 and L1 have a similar ventrolateral pattern of termination in lower levels, however, at rostral levels preterminal debris was present throughout the width of the nucleus. Fibers from L1 and L3 in the bushbaby form a complex longitudinal network with the medullary region of the nucleus in segments T11 to T8. Afferents from levels T5 in Tupaia and L6 in Galago projected ipsilaterally to the nucleus from level L3 to T10, and T8, respectively. Fibers from these segments terminated throughout the extent of the column at L3 and, rostrally projected to more dorsal regions of the nucleus. In this study, fibers from S2, and S3 and CCO2 did not terminate in Clark's column. Both the segmental distribution of hindlimb dorsal root fibers and their pattern of termination in Clark's nucleus in the tree shrew were similar to that reported in quadrupedal primates and other quadrupedal mammalian forms. The results of this study were interpreted as evidence which relates the complex organization of the Clark column system in the lesser bushbaby to its vertical clinging and leaping style of locomotion.