824 



A MANUAL OF ANATOMY 



Malpighian Corpuscles. — A. Malpighian corpuscle of the kidney is 

 a glomerulus or small ball of convoluted capillary bloodvessels, 

 having two vessels connected with it, one of which is an afferent 

 artery and the other an efferent vessel. The 

 vessels of many of the corpuscles are col- 

 lected into bundles, an arrangement which 

 renders these corpuscles lobulated, the 

 number of lobules varying from two to five. 

 Each corpuscle lies within a capsule of 

 Bowman, and the flattened epithelium of 

 the capsule is reflected over the corpuscle 

 from the points of entrance and exit of the 

 afferent and efferent vessels. The epithelial 

 cells covering the corpuscle are thicker and 

 less flattened than those lining the capsule 

 of Bowman, and are better marked in 

 early life than in the adult. In the case 

 of the lobulated corpuscles the epithelial 

 investment dips in between the component 

 lobules. The epithelium of Bowman's 

 capsule and the epithelium of the corpuscle, 

 which in each case forms a single layer, are 

 separated from one another by a slight 

 interspace. The diameter of a Malpighian 

 corpuscle is about .j^^^ inch. The corpuscles 

 are confined to the cortex of the kidney, 

 where they lie in rows in the labyrinth 

 between the medullary rays. There is a 

 narrow zone immediately within the ex- 

 ternal capsule, and another narrow zone 

 close to the Malpighian pyramids, from both of which Malpighian 

 corpuscles are absent. 



The capsular branches of the interlobular arteries supply the 

 external fibrous capsule of the kidney, in which they anastomose 

 with branches of the lumbar arteries from the abdominal aorta. 



The arteriae rectae (medullary), or vasa recta (true), arise from 

 the concavities of the cortico - medullary arterial arches, and at 

 once enter the boundary zones or basal parts of the Malpighian 

 pyramids. Here they break iip into bundles of straight, slightly 

 diverging arterioles, which run between the bundles of straight, 

 slightly converging uriniferous tubules, a mutual arrangement 

 which imparts to the Malpighian pyramids a longitudinally-striated 

 appearance. The capillary networks formed by these arterioles 

 have necessarily elongated meshes. It is to be noted that the 

 Malpighian pyramids derive their blood-supply from two sources, 

 namely, (i) the arteriae rectae, or vasa recta (true), from the cortico- 

 medullary arterial arches, and (2) the false vasa recta from the 

 efferent vessels of those glomeruli which lie nearest the Malpighian 

 pyramids. It is also to be noted that a Malpighian corpuscle of 



Fig. 356. — Diagram 

 SHOWING A Malpig- 

 hian Corpuscle of 

 THE Kidney with its 

 Afferent and Ef- 

 ferent Vessels, and 

 A Proximal Convo- 

 luted Tubule with 

 its Venous Plexus 

 (Bowman). 



!• Glomerulus 



2. Bowman's Capsule 



3. Uriniferous Tubule 



4. Interlobular Artery 



5. Afferent Vessel 



6. Efferent Vessel 



7. Venous Plexus around 



Tubule 



8. Interlobular Vein 



i 



