Studies from the Morphological Laboratory in the University of Cambridge Volume 1 - Softcover

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated.1880 Excerpt: ... On the Early Development of the Anterior Part of the Wolffian Duct and Body in the Chick, together with tome Remarks on the Excretory System of the VerteBrata. By Adam Sedgwick, M.A., Fellow of Trinity College, Cambridge. With Plate III. The following paper is divided into two parts. The first part contains an account of observations on the development of the Wolffian duct and anterior Wolffian tubules in the chick, being supplementary to my paper on the "Kidney of the Chick."1 The second part is devoted to a discussion of the vertebrate excretory system in general. I. Early Development of the Wolffian Dnct and Anterior Wolffian Tubules in the Chick. The first trace of the Wolffian duct is visible in an embryo with eight protovertebrae as a slight projection from the intermediate cell mass towards the epiblast in the region of the 7th and 8th protovertebrae. The projection also extends back behind the region of the protovertebrae for a short distance. In a chick with nine or ten protovertebrae a similar condition is found, i.e. a projection from the intermediate cell mass towards the epiblast in the region of the 7th, 8th, 9th, and 10th protovertebrae, and for a short distance behind the region of the protovertebrae. In a chick with ten protovertebrae the projection is beginning to show signs of separation from the intermediate cell mass at certain points. The appearance presented by the rudiment of the Wolffian duct in the 10th segment of a chick with ten segments is shown in fig. 1. In a chick with eleven protovertebrae the rudiment of the Wolffian duct is still present as a projection from the intermediate cell mass in the region of the 7th, 8th, 9th, 10th, and 11th protovertebrae; but behind the region of the protovertebrae it has grown back for a short...