Lymphatic system of frog consists of lymph, lymph vessels, lymph hearts, lymph spaces and spleen. Lymph is a colorless fluid which oozes out of blood capillaries and directly bathes the tissue cells.
As it is a filtrate of blood it closely resembles the plasma in its composition. Lymphatics or lymph vessels carry the lymph and in frog open into the four lymph hearts. These lymph hearts are located on the dorsal side of frog's body. The anterior that is the front pair is situated below the shoulder blades that is the scapulae. The posterior that is the hind pair is on either side of a long, rodlike bone called urostyle, formed by the fusion of last few vertebrae. The anterior pair opens into the subclavian vein and the posterior pair into femoral vein.
The lymph hearts rhythmically and slowly contract to drive the lymph into the veins. It is possible to see the lymph hearts beat by looking on the dorsal surface on either side of the urostyle. In the toad normal lymph heart rate is about 50 beats per minute. Thus the lymph emerging out of blood ultimately merges into the blood. It returns the proteins back to blood.
In our body there are no lymph hearts and the return of lymph depends to a great extent on squeezing action of skeletal muscles like the ones in calves. Any one who has to stand continuously for long hours on his feet benefits by shuffling the feet and wiggling the toes. Swelling of feet that is edema is common in people who as a professional hazard have to keep standing for a long time. By stretching limbs we feel better. By placing a couple of pillows beneath feet while lying down for rest helps lymphatic return to heart in people who find their feet and legs swollen due to inadequate lymphatic return.
For further reading - about toad lymph flow pl. visit http://www.sfu.ca/biology/faculty/farrel... and
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