The Estrous Cycle of Two Species of Kangaroo Rats (Dipodomys microps and D. merriami)

The estrous cycle of the kangaroo rats Dipodomys merriami and D. microps entails spontaneous ovulation and a spontaneous luteal phase. Corpora lutea are present throughout the cycle. The modal cycle length is 12 days in D. microps and 13 days in D. merriami, a significant difference. The duration of the cycle is unaffected by mating with a sterile male. Vulvar swelling and vaginal opening are conspicuous external indicants of estrus. The …