Anatomy of the Cat

by Jacob Reighard; H. S. Jennings

Make a diagram (a) of the arterial system as a whole; (b) of the venous system as a whole.

THE LYMPHATIC SYSTEM ([p. 330]).

It will hardly be found practicable to have each student make a dissection of the lymphatic system, and such parts of it as are to be studied may best be shown on a specimen prepared for demonstration purposes.

The thoracic duct and the receptaculum chyli may be demonstrated by the following well-known method: A lean cat is fed with milk about two hours before killing it. An egg may be beaten up with the milk to advantage. Kill the cat with chloroform, and inject the arteries with colored starch through the femoral, in the usual way. The thoracic duct, the receptaculum chyli, and the lymphatics leading to the receptaculum chyli will be colored white by the milk, and can therefore be easily followed. For this purpose the abdomen should be opened, and the left side of the thorax removed, as in the dissection of the blood-vessels. The thoracic duct will be found at the left side of the aorta and may then be traced in both directions.

For a more complete study of the lymphatics they should be injected. This is done as follows: Make a glass canula with a small point, and leave the point sharp. Connect this to the syringe by means of a rubber tube. Use a saturated solution of soluble Prussian blue as injecting fluid. Employ a freshly killed animal.

For injecting the lymphatics of the limbs, make with some pointed instrument, as the tracer, a small hole in one of the pads on the sole of the foot. Introduce the point of the canula into this opening and inject the fluid. This will pass into the spaces in the connective tissue of the pad, which will swell up, and the colored fluid will pass from the connective-tissue spaces into the lymphatics. Pressure must be maintained with the syringe for a considerable time,—fifteen minutes to a half-hour for a good injection of the main trunks of the lymphatics of the limbs. The movement of the fluid should be facilitated by pressing and manipulating the limb at the same time with the hand,—in such a way as will tend to drive the fluid proximad.

The lymphatics of the head may be injected in a similar manner, the canula being introduced into the upper and lower lip, or into the bare surface at the end of the nose.

The internal lymphatic vessels may be injected by injecting the lymphatic glands with which they are connected. This may conveniently be done as follows: Draw out to a fine point the tip of an ordinary pipette or medicine-dropper. The point should be fine, but should taper rapidly in a conical fashion, so that when the point is inserted the part of the glass tube behind it will close up the opening.

Fill the pipette with soluble Prussian blue; insert the point into the gland, and inject the fluid slowly. The lymphatic vessels passing from the glands will be filled. By injecting thus the large lymphatic gland (“pancreas Aselli”) in the mesentery, the abdominal lymphatics, the receptaculum chyli, and the thoracic duct may be injected.

By using thin gelatine colored with Prussian blue as an injecting fluid permanent preparations may be obtained; of course the process of injection is then less simple, and should be looked up in some manual of methods.