ABSTRACT
The most common techniques to obtain fi sh metaphase plates involve the cephalic part of the kidney as a source of haematopoietic tissue and peripheral blood leukocyte culture (Denton 1973; Blaxhall 1975; Gold et al. 1990; Klinkhardt 1991). These methods have two main limits: a) the quality of results may vary among different fi sh species (freshwater, marine, tropical or cold water); b) each individual may respond differently to treatments according to seasonal changes, age, sexual maturity and general physiological conditions. These diffi culties may be mostly overcome by the establishment of primary cell lines from connective tissue explants.
