![]() ![]() In this way sperms enter the ureter of kidney through vasa efferentia. The Bidders’ canal communicates with the ureter through collecting tubules of kidney. The vasa efferentia consist of a variable number of slender tubes arising from the inner margin of testis and extend within the mesorchium and then enter the inner margin of the kidney to open into the Bidders, canal. They serve as a sort of storehouse of nutrients which are provided to the developing spermatozoa and during hibernation. Just in front of each testis are found attached yellowish finger-like processes. The testis are rounded or ovoid, light yellow bodies attached to the antero-ventral surfaces of the kidneys by a double fold of peritoneum, the mesorchium.Īctually each testis is surrounded by peritoneum, which is extended dorsally as a double membrane, the mesorchium, to the dorsal side of the body cavity, where its becomes continuous with the general coelomic lining. 18.61) includes a pair of testes attached to kidneys, vasa efferentia and a pair of urinogenital ducts. When bladder is full, its involuntary muscles contract, the urine is forced into the cloaca which is voided at intervals through the cloacal aperture. It is stored in the urinary bladder for a time. The substances that are useful, such as glucose, amino acids, inorganic chlorides and some water are reabsorbed from the filtrate and put back into the blood of the capillaries of renal veins, while harmful substances such as urea and other salts along with water form urine which passes through the collecting tubes into ureters and goes to the cloaca. In the convoluted tubules selective reabsorbtion of useful substances takes place. The glomerular filtrate passes through the thin wall of the Bowman’s capsules into the lumen of uriniferous tubules and the filtered blood goes into renal vein through the efferent arteriole. The glomerular filtrate does not contain corpuscles nor plasma proteins, it has plasma, wastes and crystalloids consisting of urea, inorganic salts, glucose and large quantities of water. Blood comes to glomeruli from afferent arterioles which have a wider lumen then the capillaries so that the blood in glomeruli is under high pressure which causes filtration of blood. The blood brings these substances into the kidneys through the renal portal veins. They carry wastes from the coelom into renal veins in frog or in uriniferous tubules in tadpoles.ĭue to continuous catabolic activities certain substances are formed which are harmful to body, hence, their elimination is very essential which is done by the kidneys. Ventral ciliated funnel-shaped nephrostomes. In turn all the transverse collecting tubules open into a longitudinal Bidder’s canal lying towards the inner margin of kidney and towards outer margin into the ureter. The Bowman’s capsule along with its glomerulus is called Malpighian body or corpuscle tubules.Įach tubule opens into the collecting tubule which runs transversely across the kidney towards the dorsal surface. The tubule gets the blood supply from the capillaries of efferent arteriole and renal portal vein. From the glomerulus blood is collected by efferent arteriole which joins with a renal vein. These are lined with a glandular and at places with ciliated epithelium. Uriniferous tubules are the functional units of kidney. Each renal or uriniferous tubule starts as a thin, double-walled ciliated cup, the Bowman’s capsule enclosing a bunch of blood capillaries, the glomerulus which receives blood from an afferent arteriole of the renal artery. Each kidney is composed of a number of (about 2000) twisted renal or uriniferous tubules held together by connective tissue and richly supplied with blood vessels and their capillaries. The kidneys are most of the red blood corpuscles. Cloaca opens outside by a cloacal aperture placed at the posterior end of the body between the two hindlimbs. It is a small, medium sac receiving the anus, urinogenital apertures and the opening of urinary bladder. ![]()
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