Frog:Lymphatic system

 It Consists of lymph, lymph vessels, lymph hearts,  lymph spaces and spleen.

• Lymph: Blood is regularly filtered from Capillaries into intercellular spaces forming tissue fluid called lymph. the lymph bathes the tissues and lubricates the internal organs. It is like plasma with leucocytes but lacks erythrocytes and Some blood proteins. It acts as middle man between blood and tissues by passing nutrients and oxygen to Cells and metabolic wastes to blood. This tissue fluid is Constantly removed into lymph vessels in which it is Called lymph.
• Lymph vessels: Are also called lymphatics are thin walled delicate vessels of various sizes forming network. these lymph Capillaries unite to form larger vessels which open into venous system thus returning lymph back to blood from which it Originates.
• Lymph hearts: In Frog; Lymph vessels open into Veins at four places. At each opening the lymph vessel forms a small  rhythemically Contractile sac like structure Called lymph heart which slowly drives lymph into vein. thus, Frog has 2 pairs of lymph hearts. one pair Situated anteriorly below scapula and open into subscapular vein while another pair lie posteriorly on either side of the tip of urostyle and open into femoral vein.
• Lymph spaces: In Frog, some lymph vessels become dilated to form huge lymph Channels or sinuses. There are about 20 subcutaneous spaces under skin because of which the Skin is loosely attached. The most important subvertebral lymph sinus lies above Kidneys.
• spleen: A small, round and reddish dark gland lying in mesentry near rectum is spleen. It is largest lymphatic tissue in body. It destroys worn out erythrocytes and produces antibodies, new erythrocytes and lymphocytes which are phagocytic in nature.