MACROPHAGE ACTIVITY IN ORGAN-CULTURES OF THE AVIAN COCHLEA - DEMONSTRATION OF A RESIDENT POPULATION AND RECRUITMENT TO SITES OF HAIR CELL LESIONS

The factors that regulate the repair and regeneration of the sensory h air cells of the inner ear are not understood, Previous studies of hai r cell injury in the lateral line sensory organs of amphibians and the cochleae of mammals have demonstrated that macrophages and other leuk ocytes are recruited to sites of hair cell lesions, The present study examined the distribution and activity of macrophages in organ culture s of the avian cochlea, a system whose regenerative abilities have bee n widely studied, Cochleae were removed from chicks and placed in orga n culture, and precise hair cell lesions were created using a laser mi crobeam, Macrophages in the cultures were identified using histochemic al, immunocytochemical, and morphologic criteria, It was found that (a ) cultured cochleae contained a resident population of macrophages, an d (b) increased numbers of macrophages were recruited to the sites of hair cell lesions, Furthermore, the latency of macrophage recruitment to lesions is consistent with a suggested role for macrophages in the initiation of hair cell regeneration, (C) 1997 John Wiley & Sons, Inc.