Assistant Laboratory Animal Technician (ALAT) Practice Exam

What physiological response occurs in female rats shortly after giving birth?

1. Delayed pregnancy

2. Postpartum estrus

3. Diurnal rhythm

4. Hormonal surge

The correct answer is: Postpartum estrus

The physiological response that occurs in female rats shortly after giving birth is postpartum estrus. This is a unique reproductive characteristic in some rodent species, including rats, where the female becomes receptive to mating almost immediately after delivering her pups. This allows for the possibility of a subsequent litter to be conceived shortly after the current litter is weaned, maximizing reproductive efficiency. Postpartum estrus is typically observed within 24 to 48 hours after delivery, which is advantageous for the species' survival and reproduction strategy. During this period, hormonal changes in the female’s body prompt the return of estrous cycles and prepare her reproductive system for potential fertilization. This reproductive trait helps ensure the continuity of the species despite challenging environmental conditions and contributes to the rapid population growth that can be observed in rats. In contrast, delayed pregnancy refers to a time when a female is not in a reproductive state, which does not occur immediately postpartum. Diurnal rhythm relates to the 24-hour cycle affecting biological processes, and while hormonal changes do occur, the specific response relating to mating readiness is best categorized as postpartum estrus.