Cytologie comparée deMus (Leggada) Minutoides minutoides Smith D'afrique du Sud et d'une forme voisine de l'Angola

Abstract

In the pigmy-mouse,Mus (Leggada) minutoides minutoides A. Smith, 1834 from South-Africa, the author (1964) has described a chromosome complement of 18. The 16 autosomes are metacentric. TheX is big and metacentric, theY short and acrocentric. Owing to the fact that, at the first metaphase, both sex-chromosomes are united through a true chiasma, it was supposed that theY was primitively of the translocated type (TR), like theX, and that an intercalary deletion had destroyed the main part of the autosomic segment of theY, leaving only a small telomeric piece necessary for the formation of a chiasma. This hypothesis is confirmed by the analysis of pigmy-mice from Angola which morphologically are very like but not identical to the South-African form. The single chromosomic difference is the shape of theY which is big and submetacentric, also of theTR type.