Meiotic nondisjunction in male Snell dwarf mice.

Male hypopituitary Snell dwarf mice showed significantly more autosomal univalents in diakinesis-metaphase I (7.75 percent) and more anaphase I nondisjunction (2.68 percent) than normal mice (autosomal univalents: 4.9 percent; nondisjunction: 1.00 percent). The values of male dwarf mice, artificially made hyperthyroid, were between values of untreated dwarfs and normals (autosomal univalents: 5.25 percent; nondisjunction: 2.25 percent), but could not be shown to differ significantly from either value.