in marsupials, such as opossum and kangaroo , the life span of the corpus luteum is similiar in pregnant and nonpregnant females.
在有袋目动物中,如负鼠和袋鼠,妊娠和非妊娠母兽的黄体存在时间相似。
but on behavioral measures, rat moms perform significantly better on spatial working memory tests than nonpregnant rats, with first-time moms performing the best of all.