Abstract The purpose of this study was to demonstrate the histological effects of amniotic fluid on bone healing in the rabbit fetus. Fetal femurs (n=34) were fractured in the diaphysis and two experimental groups were estab- lished. In group A fetuses (n=18), the fracture ends were bathed in amniotic fluid through their unsutured skin wounds. In group B fetuses (n=16), the fracture sites were isolated from amniotic fluid by suturing the wound edges. Nonoperated fetuses were used as control group (n=9). The fetuses were sacrificed on the first, third and seventh postoperative days for histological studies. His- tological examination of the specimens was performed to detect inflammation, fibroblastic proliferation, bone cel- lularity, callus and cartilage formation. The results were compared, using the Fisher exact chi square test criteria, where no statistically significant differences were detect- ed between group A and group B ( P>0.05). Key words Fetal bone healing · Amniotic fluid Histology Introduction Recent developments in fetal diagnosis have initiated a new era in medicine and the fetus is now regarded as a new patient group [2,3,20]. Various research studies have been performed on various tissues of fetal animals [5,8,13,14,17,31,34–38,41]. Although fetal animals have been subject to a considerable number of experimental studies, the human fetus has been operated on only over the last 20 years and until now, only lethal diseases have been considered ethically appropriate for fetal surgical manipulation [1,9,15,16,21,24]. It is likely that at some point, elective surgery on the human fetus will be per- formed to harness its scarless wound healing and its high regenerative capacity [6,9,16,41]. A number of studies have proved that amniotic fluid may have significant effects on scarless fetal wound healing, not only due to its physical properties, but also to the high hyaluronic acid content and hyaluronic acid stimulating activity, growth factors, enzymes, hor- mones, and immunological components [3,7,12,21,23]. Unlike skin, fetal diaphragmatic wounds are known to heal by scar formation. Longaker et al. [22] unsuccess- fully bathed diaphragmatic incisions with amniotic fluid in the hope that scar formation would be prevented or reduced. However, they failed to demonstrate any such effects. Although bone is a mesothelial tissue, in adults it has an ideal remodeling capacity under favorable circum- stances [10,19,32]. It was decided to investigate whether or not this specialized tissue could be affected by the presence of amniotic fluid. An experimental study was performed on fetal rabbits, in order to find out whether, by bathing fractured bone ends with amniotic fluid, cel- lular differentiation could be induced or not. To the best of our knowledge, this was the first research project to examine the effects of amniotic fluid on the early cellu- lar changes of fetal bone tissue. Materials and methods This study was performed on 74 fetuses of 30 pregnant albino New Zealand rabbits of 3–5 kg. Sixty-five fetuses were operated on, but 37 fetuses survived, three fetuses were excluded from the study and the remaining 34 formed the experimental group, while nine nonoperated fetuses were the control group. A. Kayıkçıog ¯lu ( ✉ ) 38 Sokak 4/4, 06500 Bahçelievler, Ankara, Turkey e-mail: akayikci@hacettepe.edu.tr Tel.: +90-312-215-1577, Fax: +90-312-309-0445 A. Kayıkçıog ¯lu · A. Keçik Department of Plastic and Reconstructive Surgery, Hacettepe University School of Medicine, Ankara, Turkey H. Çelik Department of Morphology, Hacettepe University School of Medicine, Ankara, Turkey Ö. Özkaya Department of Pathology, Hacettepe University School of Medicine, Ankara, Turkey Eur J Plast Surg (2000) 23:272–277 © Springer-Verlag 2000 ORIGINAL A. Kayıkçıog ¯ lu · A. Keçik · H. Çelik · Ö. Özkaya Histologic effects of amniotic fluid in the early phases of bone healing: an experimental study on rabbits Received: 24 March 1999 / Accepted: 15 September 1999