Development of the Glycogen Body of the Chick Spinal Cord. II. Effects of Unilateral and Bilateral Leg-Bud Extirpation

Abstract

The size of certain components of the spinal cord and sciatic nerve has been reduced indirectly by radical leg bud extirpation in an attempt to determine whether the size of these components controls the development of the glycogen body in any way. There is a definite reduction in length of the glycogen body following both unilateral and bilateral leg bud extirpation. The usual bilateral symmetry of the glycogen body is lacking following unilateral leg bud extirpation, and may be lacking following bilateral leg bud extirpation if the removal of the leg bud is less complete on one side than on the other. There is little, if any, reduction in volume of the glycogen body prior to 15 days of incubation, but there is a suggestion that after the 15th day the volume of the glycogen body will be smaller in operated than in normal embryos. This is perhaps correlated with a change in the growth characteristics of the glycogen body at about the 15th day demonstrated by Watterson (''49). Size and shape of the cord at the glycogen-body level appear to control precisely both size and shape of the adjacent vertebral canal; however the control of the former over the latter cannot be due to mechanical pressure alone since the size of the vertebral canal greatly exceeds that of the contained spinal cord in the lumbosacral region.