Fig. 3.

Loss of Ik impairs normal pituitary development. (a) Morphometric evaluation of pituitary size was estimated by the summation of areas of serial cross sections starting from the midline to the lateral wing. The summation yields a curve equivalent to half the pituitary as shown in b. (b) Pituitaries of 2-week-old, Ik-null (KO) mice are smaller than those of their WT controls, and the HET mice are an intermediate size. (c) Quantification with image analysis software yields a result equivalent to half the pituitary mass. Note the disproportional change in the GH-positive area of HET animals compared with pituitary size (see b) that may explain the lack of a dwarf phenotype. In contrast, KO mice have markedly reduced pituitary GH-positive mass.