The influence of stress treatment on femur cortical bone porosity and medullary bone status in Japanese quail selected for high and low blood corticosterone response to stress.

1. Femurs taken from Japanese quail (Coturnix coturnix japonica) genetically selected for either exaggerated (HS; high-stress) or reduced (LS; low-stress) blood corticosterone (B) response to unfamiliar environments were examined to determine their cortical bone porosity (CBP; degree of osteoporosis) and medullary bone (MB) status following treatment with or without stress. 2. Femur CBP was elevated in both sexes of stressed, HS-line quail and was attributed directly to the presumably exaggerated blood B responses known to occur in this line as a consequence of the stress treatments used. 3. The increase in CBP in stressed, HS-line birds occurred independently of changes in the numbers of osteoclast cells (CLASTS) associated with cortical bone. 4. Stress treatment was associated with lower CLAST numbers/mm2 of MB and with increased MB accretion. 5. These stress-induced effects were considered to be the consequence of a reduced rate of lay found in stressed quail hens. 6. There was only marginal evidence for a direct effect of B in stimulating MB resorption.