Histologic analysis of the effects of three different support materials within rat middle ear.

Abstract

To investigate histologic changes in the mucosa of rat middle ear after implantation of three different support materials. A prospective, controlled animal study. Three types of absorbable materials were implanted into the middle ear cavity of rats: (1) Gelfoam (purified gelatin) (Pharmacia & Upjohn Company, New York, NY), (2) Sepragel (viscoelastic gel composed of cross-linked polymers of hyaluronan) (GENZYME Corp, Ridgefield, NJ), and (3) Nasopore (a biodegradable/fragmentable, synthetic polyurethane foam) (Polyganics, Groningen, The Netherlands). Rats were sacrificed after 3 and 20 days to ascertain early and late histologic changes. The bulla of each rat was excised and prepared for microscopic examination. The histologic changes were evaluated by observation of the middle ear cavity and mucosa in terms of polymorphonuclear leucocytes (PMNL), macrophages, giant cells, fibroblasts and other cells, fibrosis, and remnant materials. The histologic appearance of gelfoam-treated middle ears was characterized by more severe acute inflammation in the short-term and prominent fibrosis in the long-term in comparison with sepragel- and nasopore-treated groups. Nasopore appeared to be prone to remnant formation and reorganization by means of fibroblastic activity. Compared with gelfoam, both sepragel and nasopore caused less histologic alterations.