ABSTRACT
Apoptosis or programmed cell death is a form of cell suicide that permits an organism to efficiently remove its redundant, abnormal, or aged cells. This process is conducted for the benefit of the organism and is executed without affecting the remaining desired cells. Apoptosis genes have been described, in the zebra fish Danio rerio and in the Atlantic salmon Salmo salar. A definite increase in the number and complexity of the apoptotic protein components has evolved up through the mammals. Many pathways lead to apoptosis but the one essential mechanism that causes the demise of the cell is the organized degradation of cellular organelles by activated proteolytic caspases. With the evolution of the birds and the concomitant inactivation of erythrocytic caspase activity in their red cells the unresolved question is raised as to what benefits accrue to the avian erythrocyte with the discarding of the caspase-based cell death program.
