|M.Sc Student||Keren Aviad|
|Subject||Influence of Estrogen on Endochondral Ossification|
|Department||Department of Medicine||Supervisors||Professor Raymond Coleman|
|Dr. Gila Maor|
An experimental study examined the effects of estrogen in models of endochondral ossification. These models included mandibular condyles in organ culture of newborn male ICR mice and also mandibular condyle-derived primary tissue culture (MCDC) and an ATDC-5 cell line (clonal mouse embryonal carcinoma cells). The study included histology, immunohistochemistry, in situ hybridization, Western blot analysis, FACS analysis and transmission electron microscopy. Results showed that estrogen causes significant changes in the ossification processes including reduction in the dimensions of chondrocytic layers with reduced chondrocytic proliferation (shown by PCNA) and early differentiation (shown by collagen type II). Estrogen increases the rate of apoptosis (TUNEL positive cells and Bax expression), osteogenesis (as shown by tartrate-resistant acid phosphastase analysis) and late markers of differentiation (shown by collagen type X). The in vivo cultures showed that estrogen reduced cellular viability (DAPI staining and MTT analysis) and increased rates of apoptosis. Results obtained with estrogen-BSA indicate that estrogen-induced pro-apoptotic effects are probably not prerequisite for its inhibitory effects on chondrogenesis and accelerated ossification. This research showed that estrogen markedly affects skeletal growth processes and improves our understanding of the mechanisms whereby excess estrogen in growing children can seriously impair their skeletal growth.