A projecting ridge or fin on the bottom of the hull of a boat or ship that improves directional control and is often weighted for added stability. 2. The principal structural member of an aircraft, resembling a ship's keel in shape and function.
The outer, reddish region, next to the capsule, is the renal cortex. This surrounds a darker reddish-brown region called the renal medulla. The renal medulla consists of a series of renal pyramids, which appear striated because they contain straight tubular structures and blood vessels.
Kidney Structure. lateral surface is convex, medial side is deeply concave medial depression leads into a hollow chamber called the renal sinus, through the entrance to this sinus (hilum) pass blood vessels, nerves, lymphatic vessels and the ureter.idney Structure. lateral surface is convex, medial side is deeply concave medial depression leads into a hollow chamber called the renal sinus, through the entrance to this sinus (hilum) pass blood vessels, nerves, lymphatic vessels and the ureter.