An Experimental Study of the Development of the Notochordal Sheath

The prime object of the studies to be described here was the investigation of the origin and epigenetic relations of the notochordal sheath. In addition, some data were collected concerning the effects on the development of the embryo of the removal of the notochord or its substitution by some other elongated strand of material, such as human hair. Many of the phenomena encountered in the latter studies have recently been described by Kitchin (1949) and Mookerjee (1952), so that it is with questions relating to the notochord sheath that we shall be chiefly concerned. It has been generally accepted up to the present time that the sheath is a secretory product of the notochord. This view is based on the descriptive studies of a number of comparative anatomists who dealt with the formation of the sheath and the origin of the vertebral column.