THE UROGENITAL SYSTEM 
1 33 
show these structures. Draw a longitudinal section showing the 
plan of structure of a simple kidney. 
For comparison with this simple kidney of the rabbit study 
the compound kidneys (i) of the cow or calf where the components 
are more or less separated, and (2) of the sheep and pig where the 
components are closely fused as in the human kidney. Draw 
a diagram of each type showing the relation of the components. 
Microscopic Study (Lab. SI. Coll.).—The real secreting organs 
of the kidney are the very numerous and complicated renal 
tubules. Each tubule begins with (a) the glomerulus capsule, 
which consists of a spherical expansion rendered two layered 
by the pushing in of one side through the ingrowth of a knot of 
blood vessels (a glomerulus). These are distributed through the 
cortex and form the renal corpuscles. From this capsule leads 
( h ) the convoluted tubule, situated also in the cortex, and leading 
into ( c ) the straight tubule, which forms a loop, consisting of a 
thinner walled descending and a thicker walled ascending region, 
extending into the medulla and back into the cortex, where it 
leads into (d) the intercalated piece, a second convoluted region, 
which leads into (e) a collecting tubule, into which many other renal 
tubules open; this passes through the medulla to reach (/) a pap¬ 
illary duct which opens upon the free surface of the papilla by a 
pore through which the secretion (urine) is constantly drained off 
into the calyx, to be carried from the kidney through the ureter. 
Study under low power a section of rabbit kidney. Identify 
the cortical and medullary regions, and note the general course of 
the tubules in each. Draw the whole section to show its general 
topography as seen under low power. 
Study under high power each region to identify (1) the cap¬ 
sules of the glomeruli with the lining of flat epithelial cells and the 
beginning of the convoluted tubule, and (2) sections of various 
regions of the renal tubules. Draw details , showing characteristic 
form of the epithelial cells of as many regions as you are able to 
identify (cf. illustrations and description in any good text-book of 
histology). 
Study for comparison, sections of the kidneys of other mam¬ 
mals, including man, also sections of injected kidney, noting that 
the knot of blood vessels of a glomerulus is not a true capillary 
