Animal models of male infertility: mice bearing single-gene mutations that induce infertility.

Genetically defined mouse models of male infertility are described in the present report. The mice were rendered infertile by one of the following gene mutations: Ames dwarf, dwarf, flipper-arm, hightail, hypothyroid, little, pygmy, stubby. The effects of each gene mutation on testicular steroidogenesis and spermatogenesis were elucidated by a comparison of the mutant mice to their normal siblings. Testicular steroidogenesis was assessed directly by determining steroid secretion by testes perfused in vitro. The study provides the first comprehensive assessment of testicular function in the mutant mice. The eight gene mutations can be classified into two groups based on the results. One group of gene mutations (Ames dwarf, dwarf, flipper-arm, pygmy) specifically depress spermatogenesis and testicular steroidogenesis. The infertility of these mutant mice can be linked to the lowered total sperm production. The second group of gene mutations (hightail, hypothyroid, little, stubby) do not specifically depress either spermatogenesis or testosterone secretion. Subsequently, the etiology of the male infertility of the second group of mutant mice is unknown. We propose that these mutant mice provide valuable experimental tools for the study of male infertility and male reproduction.