L. reuteri accelerates wound repair via an oxytocin-associated mechanism in both male and female mice.

(a) Oxytocin-deficient male mice have significantly larger wounds in day 6 after wounding compared to wild-type control mice despite consumption of L. reuteri. Wound margins are delineated with yellow outlines. (b) Impaired wound healing in oxytocin-deficient mice is characterized by delayed re-epithelialization and granulation tissue formation. The mature granulation tissue of control mice is characterized by fibrosis and vessels running perpendicularly to the layers of elongated fibroblasts. In oxytocin-deficient mice there is still edematous (early) granulation tissue with an acute inflammatory component. (c) Oxytocin-deficient mouse wounds show minimal collagen deposition and significantly more (d) neutrophils. (b) Hematoxylin and Eosin. (c) Masson's Trichrome (d). Immunohistochemistry (Diaminobenzidine chromogen, Hematoxylin counterstain). Scale bars (b) = 25 µm; (c) (d) and (e) = 50 µm.