The keel bone in laying hens is prone to fractures, especially on the caudal third of the keel, which is also the last part to ossify. Keel bone fractures (KBF) typically occur between 25 and 50 weeks
(A) Sagittal sections stained with Safranin-O/Fast Green. (B) Sagittal sections unstained for polarizing microscope. (C) TEM images for the superficial zone.
