Osteoclast-Like Cell Formation in Medullary Bone Marrow Cell Culture of Laying Hens

Abstract

Marrow cells were isolated from medullary bone of hens at two opposing phases, the bone formative and resorptive phases, of the egg-laying cycle. These cells were cultured for up to 14 days on cover slips. After culture, the osteoclast-like cells which were multinuclear, positive for tartrate-resistant acid phosphatase (TRAP) and formed bone-resorption pit, were observed on the cover slip. The number of them increased by 8 days of culture and decreased thereafter. Also, the osteoclast-like cell formation was prominent in culture of medullary bone marrow cells at the bone resorptive phase, compared with those at the bone formative phase. Additionally, before forming osteoclast-like cells, TRAP-positive mononuclear cells were adherent to the cover slip and later aggregated as clusters. In the clusters, the TRAP-positive mononuclear cells contacted each other and partially became multinucleated. These results show that medullary bone marrow cells contain osteoclast progenitors or precursor, and these cells differentiate into TRAP-positive precursors and terminally fuse each other to form mature and functional osteoclast-like cells. Also, the medullary bone marrow cells at the bone resorptive phase contain many osteoclast progenitors or precursors, suggesting that medullary bone marrow cells at the bone resorptive phase have high potential to form osteoclasts.

Keywords

• hen
• medullary bone
• osteoclast
• egg-laying cycle
• culture