Aspects of the tabby—crinkled—downless syndrome : I.The development of tabby teeth

The sex-linked gene tabby, Ta (Falconer, 1953), and two autosomal mimics of tabby, crinkled (cr, linkage group XIV) (Falconer, Fraser & King, 1951; King, 1956) and downless (dl, linkage group IV) (Mouse News Letter, 1960,1966) each produce a similar mutant syndrome involving the coat and dentition of the mouse. Studies on the coats of tabby and crinkled mice point to a timed gene effect causing suppression of formation of new hair follicles between and 17 days of gestation and again from birth onwards, with a reduction in the rate of growth of the follicles that do form (Falconer et al. 1951). Associated with this is a reduction in hair calibre and a lack of differentiation of the coat into hair types (Grüneberg, 1966 b). A model to explain the timed action of the tabby gene has been proposed by Dun (1959).