Textbook of Histology and Microscopic Anatomy of the Human Body (Paperback)

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. 1902 Excerpt: ...first part of the genito-urinary system to appear in the embryo is the Wolffian duct. The origin of this duct is doubtful. According to some authors (Henseu, v. Spee), it is derived from the ectoblast. Others believe it arises from the mesoblast; His and Kowalewsky, from the middle plate; and Kemak, Kolliker, and Waldeyer, from the lateral plate of the mesoblast. Rensen, Dansky, and others derive it from the coelomic epithelium. It is at first a solid rod of cells, which subsequently develops a lumen lined with epithelium-like cells. Tubules develop from this duct and form the Wolffian body. This embryonic organ was observed first, in 1759, by Wolff, who considered it the embryonic stage of-the permanent kidney. Rathke (1825) first used the term Wolffian body in connection with this organ in birds, and called the corresponding organ in mammals, Oken's body. Jacobson, in 1824, termed it the primordial kidney, and recognized that it excreted uric acid, which was carried into the allantois. The Wolffian body of mammalian embryos is a somewhat pyriform body symmetrically placed in the abdominal cavity. In early embryos it is, next to the liver, the largest abdominal organ. It consists of a tubular and a glomerular part. The glomeruli are situated medially, while the coiled tubules form the largest part of the organ. These come off from the Wolffian duct at right angles to it, and after a considerable coiling are connected with the glomeruli by means of end dilatations similar to the Bowman's capsules of the permanent kidney. In the human embryo the tubules have a somewhat S-shaped eourse. In the pig's embryo, on the contrary, the tubules are much convoluted. Their exact course has been determined (MacCallum) by means of injections into the Wolffian duct, a...