| Metestrus may be followed by anestrus, a nonreproductive period characterized by quiescence or involution of the reproductive tract. |
| If fertilization and implantation do not occur, a phase termed metestrus ensues, in which the reproductive tract assumes its normal condition. |
| This last change is an exaggeration of the physiological changes seen in metestrus. |
| Progesterone secretion also increases during metestrus and diestrus with a decrease afterwards. |
