Cyto- and myeloarchitectural studies on the lateral tuberal nucleus in simian Callithricidae and Prosimiae

The cytoarchitecture and myeloarchitecture of the lateral tuberal nucleus (LTN) were examined in five species of Callithricidae and in 21 species of Prosimiae. In this study, the LTN of the Callithricidae is described in detail and the LTN of prosimian Lemuriformes is clearly demonstrated for the first time. The LTN could not be detected in other prosimians, Lorisiformes, Tarsiformes and Tupaiiformes. In coronal sections, the LTN of Callithricidae is a round nucleus embedded within the longitudinal fiber bundles in the lateral hypothalamic area. The cytological characteristics and the rostracaudal extent of the nucleus are the same as in the LTN of higher primates and man. In prosimian Lemuriformes (Daubentonia madagascariensis, all Indrioidea examined and some Lemuroidea), the LTN is similar to that of the Callithricidae, although it is smaller and less prominent.