54 THE URINARY ORGANS. 
which is in contact with the cortex. Running up into the cortex 
almost to the capsule from the base of the Malpighian pyramid are 
delicate rays called medullary rays. The whole structure as described 
is called a renculus. While the rabbit’s kidney consists of only a single 
renculus, the human kidney consists of as many renculi as there are 
papilla. 
What kind of a gland is a kidney ? 
A compound tubular gland, made up of numerous branching 
tubules called uriniferous tubules which, with the cells lining them, 
constitute the parenchyma of the kidney. 
How is the blood distributed to the kidney ? 
The bloodvessels enter at the bases of the medullary pyramids and 
divide into large arching trunks between the cortex and the base of 
the Malpighian pyramid. Springing from the convex side of these 
arches small branches called interlobular arteries run up through the 
cortex between the medullary rays. Small twigs are given off from 
these interlobular arteries, which enter the Malpighian bodies as afferent 
arteries; breaking up into a capillary network they pass out of the 
Malpighian body as a single vessel called the efferent vessel. The 
efferent vessel then splitting up envelopes the uriniferous tubules in a 
capillary meshwork. A similar network is also seen under the capsule 
in the cortex and is known as the stellate plexus or the “stellule 
Verheyenti.” The blood is then collected in veins which follow along 
the interlobular arteries. The medullary portion of the kidney is sup- 
plied with blood from the concave side of the above-mentioned arches, 
the vessels between the tubules being called the vase recta. 
Give the names and location of the different portions of a urinif- 
erous tubule. 
In the cortical portion between medullary rays surrounding the 
Malpighian tuft is a dilatation called the capsule of Bowman. Con- 
tinuous with this is the first convoluted portion of the tubule, which 
entering a medullary ray narrows and runs down as the descending 
limb of Henle’s loop. It then ascends in the same ray as the ascend- 
ing limb of Henle’s loop comes out into the cortical portion between 
the rays as the second convoluted portion or intercalated tubule, and 
again enters the medullary ray as the straight or collecting tubule. 
These collecting tubules are at first narrower than the convoluted 
tubules, but uniting one with another they finally terminate in the 
apex of the Malpighian pyramid in a number of large tubules called 
