Locomotor development in a mouse line with disruption of the Gnrhr gene.

The six groups of mice, including males and females, wildtype (+/+), heterozygous (+/-) and null (-/-) groups, were tested for the first postnatal day in which (A) the head and shoulders could be elevated; (B) the mouse could pivot; (C) the mouse crawled and (D) the mouse walked. (F = female; M = male).