Postpartum tissue regeneration at the uterus

Problem The formation of uterine scars is a main reason for maternal disorders related to caesarean deliveries. Here, we aimed to investigate the poorly understood postpartal uterine regeneration, particularly with regards to apoptotic and proliferative processes and angiogenis of the lymphatic and blood system in mice.

Materials and methods Uterine tissue samples were collected from virgin and day 4 postpartum C57/BL6 mice. Histological sections were stained by Masson-Goldner trichrome or by immunohistochemical detection of CD31, LYVE-1, PCNA and TUNEL. The analysis focalized in the endometrium, differentiated from the myometrium by α-SMA negativity.

Results Compared to virgin uterus, in postpartum the former implantation site presented an expanded mesometrial area, spheroid in shape and surrounded peripherally by collagen. Whilst CD31+LYVE-1- blood vessels were ubiquitous in virgin and postpartum endometrium, vessels of large lumen and clusters of capillaries gathered exclusively at the former implantation site. The endometrium was largely devoid of lymphatic vessels. In contrast, the myometrium presented lymphatic vessels, particularly at the mesometrial side and of higher diameter in postpartum. TUNEL+ apoptotic cells scattered especially in the mesometrial area of postpartal endometrium, whereas their number in virgins was sparse. Proliferating PCNA+ cells located in both virgin and postpartal endometrial stroma, glands and epithelium.

Conclusions Postpartal regeneration of the former implantation site is associated to cell death and increased endometrial angiogenesis and myometrial lymphatic vascularization. The cascade of events leading to complete regeneration of the postpartal uterus and how it is modulated e.g. by uterine resident immune cells requires still further elucidation.

Publication History

Article published online:
11 October 2022