Abstract
Postpartal changes of the endometrium in primiparous Meishan pigs during the process of uterine involution were examined by morphological and immunohistological methods. Reproductive organs were collected from lactating sows (Days 1, 13, 20 and 31 after parturition) and a weaned sow (weaned on Day 28 and sacrificed on Day 31 after parturition). Cryosectioned uterine tissues were stained with Mayer's hematoxylin and eosin for histological observations. To observe membranous extracellular matrix localization, samples were treated with antibodies against laminin and type IV collagen. The diameter of the uterine horn decreased dramatically by Day 13 and slightly decreased during Days 13 to 31 after parturition. Luminal and glandular epithelial cells were low and cuboidal during lactation but became highly columnar just after weaning. During lactation, laminin and type IV collagen were localized in a winding pattern in the basal lamina of the endometrial epithelium. After weaning, they were found in the basal lamina of the endometrial epithelium in a stratum. These results suggest that uterine involution is completed just after weaning.
