T1Wh, a promising mouse strain with chromosomal markers for cleft palate research.

Attainment of the horizontal position by the secondary palatal shelves and fusion in relationship to morphological and chronological ages in T1Wh, and albino strain of mice homozygous for a 5;19 Robertsonian translocation, was found to be late and slow in comparison to other strains previously investigated. Spontaneous and cortisone-induced cleft palate frequencies of 3.5% and 100% respectively, were found in this strain. Its slow and late palatal closure, high susceptibility to cortisone, obvious marker chromosomes, and good breeding performance promise to make T1Wh a useful strain for cleft palate research.