File:Keibel Mall 2 568.jpg

Fig. 568. Model of the right mesonephros and Mullerian duct of a human embryo of 19.4 mm greatest length

(Embryo Ma. 2, from the collection of Professor Hochstetter, Vienna. The model was prepared by my students Massard and E. Chome.)

The mesonephros has undergone extensive degeneration. All the tubules in the thoracic segments and some of those in the lumbar show degeneration. Either the Malpighian corpuscle is wanting or it is rudimentary and separated from its secreting tubule; this is the case in tubules 1-12, that is to say in a full third of those present. All these tubules are also broken, either in the secreting tubule or between this and the collecting one. These latter are rarely hollow, and if so, their lumina are filled with degenerating epithelium. Finally the tubules 33, 34 and 35 consist only of collecting tubules; 33 has still a portion of the secreting tubule and near it are two large Malpighian corpuscles without any connection. Similarly tubule 31 consists only of a collecting tubule; a Malpighian corpuscle with two secreting tubules seems to correspond with it; some of the remaining tubules are broken, 14, 17, 18, 19; some have solid collecting tubules, 13, 14, 15, 16, 17, 19, 21, 23, 25 and 26, and some solid secreting tubules, 22 and 24; the collecting tubules of 28, 29 and 31 form ureter-like structures. Only the remaining tubules 20, 27, 30 and 32 are fully formed. The appearances of degeneration seen in the most caudal tubules are not to be regarded as persistent without further evidence. From older series it is seen that the lower collecting tubules which have separated from the excretory duct may acquire a new opening into a neighboring collecting tubule, just as separated Malpighian corpuscles and secreting tubules may communicate anew with neighboring tubules. By the bending of the primary excretory duct at the end of the mesonephros, the Malpighian corpuscles of the 26th to the 34th tubules are pressed together so as to form a special group, from which, later, the paragenitalis is formed. The Mullerian duct is quite independent of the ccelomic epithelium and the excretory duct; it is still straight, since its down-growing tip has just reached the head of the excretory duct.

Embryology - 25 Apr 2024        Expand to Translate
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Felix W. The development of the urinogenital organs. In Keibel F. and Mall FP. Manual of Human Embryology II. (1912) J. B. Lippincott Company, Philadelphia. pp 752-979.

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Cite this page: Hill, M.A. (2024, April 25) Embryology Keibel Mall 2 568.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Keibel_Mall_2_568.jpg

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