Extirpation Experiments Upon the Pouch Young of Didelphis Virginiana

Abstract

Extirpation experiments upon the embryonic forelimb of the rat demonstrating their inability to regenerate have been described. 1 In order to carry on this type of investigation with a more primitive animal the pouch young of the Virginia opossum, Didelphis virginiana, were subjected to a series of experiments to determine their capacity for regeneration.

The anesthetized female with new born young was stretched dorsicumbent on an operating table and the extremities fastened down. The pouch was held open by retraction and the pouch young 2 were operated upon with fine iridectomy scissors.

These preliminary operations were made in order to ascertain whether any particular locality was preferred for such treatment. Gross examination of these specimens after fixation in Bouin's fluid showed no signs of regeneration. In these experiments 1 to 5 digits or 1 foot from a posterior limb, or 1 posterior limb, or the tail were removed from a series of 16 animals. The specimens were killed and preserved at intervals from 33 to 315 days after the operation.

Unfortunately, due to the difficulties of maintaining the opossum in the laboratory, half of the experimental material was lost. Further work is planned using the young immediately at birth and, as before, confining the experiments to the posterior region of the body, which is less developed at the time of birth.