Surface activity on the periosteal and corticoendosteal envelopes following continuous progestogen supplementation in spayed beagles.

Resorptive and formative characteristics on the periosteal and corticoendosteal bone envelopes were assessed on the ribs of intact, spayed and medroxyprogesterone acetate (MPA)-supplemented Beagle dams. Histomorphometric analyses of the alterations on surface activities of these two envelopes were carried out using tetracycline labeling. It was found that continuous administration of progestogen decreased the extent of resorptive surfaces on the corticoendosteal surfaces of progestogen-treated animals vs. spayed animals. On the periosteal surfaces the progestogen-treated dogs showed a marked increase in formation when compared to spayed and intact dogs. As a result of continuous progestogen treatment, mineralization lag time was shortened on the corticoendosteum and periosteum of progestogen-treated animals when compared to the same surfaces on the bones of intact and spayed animals.