Effect of pituitary hollow fiber units and thyroid supplementation on growth in the little mouse.

Hollow fiber units containing allogeneic pituitary cells were implanted intracranially into heterozygous (lit/+) and homozygous, mutant (lit/lit) C57BL/6J "little" weanling mice. Over the 48 days of the experiment, heterozygous mice with pituitary cell implants had a lower percentage weight gain than control mice. Homozygous, mutant mice with cell implants, however, made significant weight gains over mutant controls. Long bone lengths were lower, and organ and carcass weights were higher, in heterozygous mice receiving pituitary cell implants than in control mice, but corresponding measurements in mutant mice with and without implants were not significantly different. Supplementation of the diet with thyroid powder increased the percentage weight gain during the latter half of the 48-day period in both genotypes with and without implanted cells. Thyroid-supplemented mutant mice with pituitary cell implants had significantly higher organ and carcass weights than other mutant groups. The little mouse may serve as a model for pituitary studies and for the treatment of isolated growth hormone deficiency type 1 in man.