Monodelphis domesticus: a model for early developmental wound healing.

Fetuses heal significantly differently than adults; amniotic fluid and the fetal environment have profound effects on the fetus' response to excisional wounding. The Brazilian gray short-tailed opossum (Monodelphis domesticus) is presented as a new model for early developmental wound healing. This is a small, docile, pouchless marsupial whose young, at birth, are equivalent to an 8-week gestational age human, which allows investigations of early developmental wound healing exclusive of the amniotic environment. Incisional and excisional wounds were made on the dorsum of pups 1 or 15 days after birth. The pups were killed 1, 3, or 6 days after wounding and were fixed for histology. All incisional wounds were bridged by keratinocytes within 24 hours. Day 1 excisional wounds healed 6 days after wounding with a hypertrophic layer of keratinocytes and no inflammation. Day 15 excisional wounds exhibited inflammation, focal necrosis, and healing by epithelial migration 6 days after wounding. This model allows for investigations into early developmental wound healing and exhibits responses dependent on age similar to prepartum and postpartum young of higher mammals.