THE URINARY SYSTEM: KIDNEYS 



425 



The oldest renal capsules are rounded or oval in shape (Fig. 27 e). When seen in 

 sections cut across the glomerular neck, these capsules have a diameter of 30 microns at 

 right angles to the axis of the glomerular neck. In the direction of the axis of the neck 

 the rounded capsules have a diameter of 20 microns, and the oval of 10 microns. They 

 are generally orientated in young kidneys so that the axis of the neck lies along the 





Fig. 27. One lobe of a kidney of a Blue whale foetus 18-5 cm. in length. (Jth obj. x 8 oc.) 

 a. Interlobar septum. e. Functional glomerulus. 



b. Interlobular septum. 



c. Serosa. 



d. Embryonic area. 



e 1 . Young glomerulus probably not yet functional. 

 /. Urinary tubule. 

 g. Collecting tube. 



radius of the renculus, but in older kidneys there is a tendency for them to take up 

 less regular positions. The glomerulus is of the usual type — folded irregularly on a 

 trilobed pattern. It projects into the capsule by a narrow neck (Fig. 27 e), carrying the 

 afferent and efferent blood capillaries to the glomerulus. It is often attached secondarily 

 at one or two points to the capsular wall, and is covered by a flat epithelium which also 

 lines the interior of the capsule. 



