Impaired macrophage migration in incisors absent (ia) osteopetrotic rats

Thioglycollate was introduced into the peritoneal cavity of 32-, 50- and 80-day-old normal (ia/+) and incisor absent (ia/ia) osteopetrotic rats, and 3 days later macrophages were harvested. The number of macrophages recovered from 32- and 50-day-old ia rats was significantly less than that elicited from corresponding normal littermates. The macrophages from mutants also showed a significantly impaired ability to migrate in vitro. At 80 days, the number of macrophages obtained from ia rats was not significantly different from those elicited from control rats, and their migratory function was also close to those obtained from controls. The increase in macrophage number and migrating capacity noted in 80-day-old ia rats correlates with increased marrow development at this age as described by Marks (Pathogenesis of osteopetrosis in the ia rat. Reduced bone resorption due to reduced osteoclast function, Am. J Anat 1973;138:165-190.