title: Programmed healing of membranous bone in the fetal lamb.
abstract: In fetal tissues, both soft and hard tissue healing (in long bones) have been found to be scarless. However, healing of membranous bone in the fetal craniofacial skeleton has not been well documented. Pregnant ewes (gestational age range, 80-95 days) underwent a hysterotomy, and fetal lambs had a full-thickness excision of the entire mandibular symphysis region (10 mm). Nonoperated controls were used for comparison (n = 8). After 10 days and 2 weeks, fetuses showed incomplete regeneration of the anterior mandible by examination, computed tomographic scan, and histology. By 4 weeks postoperatively, the mandibular defect had completely closed, but regenerated bony volume was less than control specimens. At 6 weeks postoperatively, the specimen demonstrated complete bony healing without scar or inflammation. Computed tomographic scan measurements for mandibular shape (length over width) was similar in experimental and control specimens. The data indicate that fetal lamb membranous bone defects heal in a scarless fashion and suggest preprogrammed migration of osteogenic tissue.
authors.affiliation: Skull Base Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA.
authors.forename: Hrayr
authors.initials: H
authors.lastname: Shahinian
authors.forename: Jamie P
authors.initials: JP
authors.lastname: Levine
authors.forename: James P
authors.initials: JP
authors.lastname: Bradley
authors.forename: Catherine
authors.initials: C
authors.lastname: O'Hara
authors.forename: Susan A
authors.initials: SA
authors.lastname: McCormick
authors.forename: Yoonah
authors.initials: Y
authors.lastname: Kim
authors.forename: Michael T
authors.initials: MT
authors.lastname: Longaker
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000502:physiology*; D002921:Cicatrix; D005260:Female; D005333:Fetus / Q000502:physiology; D005592:Fracture Fixation; D017102:Fracture Healing / Q000502:physiology*; D008337:Mandibular Fractures / Q000503:physiopathology; D008445:Maxillofacial Development / Q000502:physiology*; D023421:Models, Animal; D011247:Pregnancy; D012756:Sheep; D014945:Wound Healing / Q000502:physiology