Effects of estrogen on the proliferation and differentiation of osteogenic cells during the early stage of medullary bone formation in cultured quail bones

Abstract

Quail bone fragments cultured in the medium containing 17β estradiol (E2) were examined morphologically. On the endosteal bone surface of bones cultured in serum-containing medium, preosteoblasts were observed and labeled by3H-thymidine after 24 h of culturing. After 48 h of culturing, medullary bones occasionally appeared along the endosteal surface, and their bone surfaces were covered with labeled osteoblasts. These osteoblasts were frequently found when added E2. On the endosteal bone surface of cultured bones in the serum-free medium alone, bone lining cells were observed and not labeled throughout the culture period. On the endosteal bone surface of bones cultured in the serum-free medium containing E2, labeled preosteoblasts were seen after 24 and 48 h of culturing. However, osteoblasts did not appear. These findings suggest that estrogen acts directly on the proliferation and differentiation of osteogenic cells.