Tracheal transplantation: cytological changes studied by scanning and transmission electron microscopy in the rabbit

Our goal was to offer a comprehensive cytological study of the changes in the trachea after experimental transplantation of the organ.

Autografting of four tracheal rings was done in rabbits and tracheal samples were observed by electron microscopy from 1 week to 6 months after the surgery was performed.

Transmission and scanning electron microscopy were used to investigate the fine structure of tracheal samples of rabbits submitted to autotransplantation, and quantitative methods were used to compare several cytological parameters of the different groups of animals.

We found that tracheal autografting was associated with acute injury of ciliated cells expressed by loss of more than 90% of cilia density on the tracheal epithelium 1 week after the transplantation was performed. The loss of cilia was balanced by an increase in mucous cells present on the tracheal lumen. Recovery of ciliated cells was observed 1 month after the tracheal autografting was performed. In contrast, only mild cytological modifications were seen in the cartilage tissue of the autografted trachea during the first weeks of transplantation; the structural alterations of the cartilage progressed up to the third month after transplantation, resulting in a moderate tracheal stenosis.

The data indicate that 1) autotransplantation of four tracheal rings is a viable surgical procedure; 2) tracheal grafting causes severe acute changes of the epithelium that are, however, reversible in nature; whereas 3) the initial mild alterations induced by the autografting in the cartilage may evolve into tracheal stenosis.