Résumé
Hemic proliferative disease in the bay mussel, Mytilus edulis, has been studied following mortalities in Washington State (USA). The disease has been reproduced in the labortory. The establishment of this experimental model led to study tumoral characteristics of the atypic hemocytes : ultrastrure, in vitro cultivation, transplantation. The infectious etiology of this tumor has been verified. It has been hypothesized to result from a viral infection since retrovirus-like particules have been observed following induction by bromodeoxyuridine. Specific monoclonal antibodies against atypic hemocytes have been obtained and characcterized