Experimental canine tracheal grafts with reversible squamous metaplasia.

A technique for making bistomal tracheal pedicle grafts in dogs is described. The grafts were placed subcutaneously in the neck, and their mucosa was readily accessible to serial manipulations, endoscopic examinations, and biopsies, without requiring anesthesia. Squamous metaplasia developed in 5 of 8 grafts, or 63 per cent, within 1 week. Within 12 weeks, squamous metaplasia was seen in all grafts, and it was consistently accompanied by basal hyperplasia. After orthotopic reimplantation of the grafts, the squamous metaplasia proved to be reversible within 4 weeks. The preparation used for making these observations is a valuable research tool for sequential studies of the respiratory tract mucosa.