RATE OF HISTOLYSIS OF ANURAN TAIL SKIN AND MUSCLE DURING METAMORPHOSIS

Abstract

The factors responsible for the atrophy of the larval anuran's tail will no doubt require considerable further work before a complete and adequate explanation can be derived. The main results and conclusions reached to date may be briefly reviewed as follows: Barfurth (1887) first suggested that the growing urostyle occluded the adjacent dorsal aorta and so cut off the blood supply to the tail. Mercier (1906) later found phagocytes in the muscle masses of the tail which contained carmine granules previously injected into the dorsal lymph sac. This indicated that the occlusion of the aorta due to urostyle growth must be only a partial one. Bataillon (1891) studied the blood vessels of normal and atrophying tails and described a change in vascular distribution (notably of the capillaries) in the latter. More recently, Morse (1918) and Bradley (1922) have reiterated Barfurth's explanation and suggest that the reduced blood supply to the tail enables the CO2 and various acid metabolites to accumulate. The result is the activation of the autolytic enzymes with consequent histolysisand general atrophy of the tail. Morse also suggested that a possible lowering of the blood pH might be the fundamental causative factor involved.