INHERITANCE OF PREDISPOSITION TO CATALEPSY IN MICE

''Pinch-induced'' catalepsy (excessive freezing) was studied in mice o f nine inbred strains. The CBA/Icg strain had the highest predispositi on to catalepsy, with 56% males and 73% females exhibiting 120-s immob ility after four tests. A Mendelian analysis of predisposition to cata lepsy was performed on CBA/Icg and AKR/J mice contrasting in this trai t. Reciprocal F1 hybrids did not display freezing after 10 tests. The number of cataleptic and noncataleptic animals among the F2's and in t he families of the CBA x F2 backcrosses agreed with the hypothesis tha t the pronounced predisposition to catalepsy in the CBA/Icg mice was d etermined by a single autosomal locus in homozygous recessive conditio n.