Do Both Males & Female Frogs Have Cloacas? | Animals - knifedirectory.info
Both the excretory and reproductive systems are under endocrine control but are also influenced by the external environment. Source for information on. Since the excretory and reproductive systems are closely associated, hence, it is customary to call the two systems together as a urogenital or urinogenital. The excretory system of a frog consists of a kidney pair, a pair of ureters, a urinary or the genitourinary system because often the reproductive and urinary system The phylogenetic tree shows the relationship and evolution of animals.
Actually 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. Just in front of each testis are found attached yellowish finger-like processes.
Faculty of Biological Sciences, University of Leeds
They serve as a sort of storehouse of nutrients which are provided to the developing spermatozoa and during hibernation. 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.
In this way sperms enter the ureter of kidney through vasa efferentia.Frog - Digestive - Respiratory - Circulatory - Excretory - Nervous - Reproductive system -
Bidders canal and collecting tubules. The vasa efferentia are originally outgrowths of the walls of the Malpighian corpuscles which become connected with the testis. Ureter in male frog is a urinary duct as well as a vas deferens to convey the urine and spermetozoa.
Hence, it is called a urinogenital duct. Both the ureters open into the dorsal wall of cloaca separately on urinogenital papillae. Histological, each testis Fig. In the connective tissue are found blood capillaries and lymph vessels, nerves, muscle fibres and groups of interstitial cells in between the lubules. These cells secrete a hormone testosterone which brings the secondary sexual characters of the individual.
The wall of tubule is lined by germinal cells which produce sperms by spermatogenesis. The mature sperms are found in bundles in the lumen of tubules floating in the spermatic fluid. From the ureter they pass into the vesicula seminalis where they are stored.
The excretory organs are the same in female frog as found in male frog, but they do not have any connection with the reproductive organs. The ureter does not dilate as vesicula seminalis and no ducts from ovaries open into the kidneys.
Excretory and Reproductive Systems | knifedirectory.info
The cloaca serves as a common passage for urinary and genital systems as in the male frog. Female reproductive system Fig. Both the ovaries are attached to the dorsal abdominal wall, close to the kidneys, by a fold of peritoneum called mesovarium.
The ovaries are large, lobulated hollow sac-like structures. In breeding season the ovaries become greatly enlarged. Histologically, the wall of each ovary Fig. The germinal epithelium gives off several small groups of cells or oogonia which form ovarian follicles. Within each follicle a central cell enlarges forming ovum.
It contain a nucleus and granular yolky cytoplasm. Remember this had a gut and a coelom lined with thin mesothelium.
Now a large cavity with a thin wall like this is ideal for dumping waste, and it seems that the coelom was so used. The result, of course is that it would gradually fill with ions, salts, water and what have you. This seems to have been countered by forming paired lateral ducts, lined with cilia and called nephrotomes. The cilia control the direction of the fluid, outwards.
Interestingly these excretory ducts probably also carried gametes to the sea, even at this early stage. Now the animals we are talking about were segmented, like sliced bread, and had one coelom and one pair of nephrotomes per segment. When segmentation was abandoned in favour of an open plan coelom the nephroptomes became rationalised with paired openings still but only one exit to the sea, towards the rear.
The open plan coelom developed at about the same time as the circulatory system, and this became involved. The dorsal aorta ran close to the nephrotome and formed a knot of capillaries, a glomerulus, associated with each nephrotome. Finally the ciliated duct to the coelom was lost This set-up, a glomerulus, a nephric tubule essentially a space and a duct passing posteriorly has formed the basis of the kidneys ever since.
I say kidneys not because we have two of them but because during vertebrate history there have been three pairs of kidneys. The most primitive of these was anterior, the next more posterior and the last most posterior. They are called pronephros, mesonephros and metanephros. The pronephros is still seen in some fish and amphibian larvae: The mesonephros is the kidney of most fishsome adult amphibia and many mammalian embryos: The metanephros develops behind the mesonephros to form the definitive kidney in mammals.
The important fact here is that it develops its own duct, the metanephric duct or ureter, which develops from the cloaca and runs forward to the developing third generation kidney. The reproductive system and its ducts.
Why are the excretory and the reproductive systems studied together as the urogenital system?
The gonads develop in the same dorsolateral region as the kidneys. Gonads are initially equipped with two sets of ducts. Well remember that nephrotomes, ciliated ducts passing to the outside originally carried germ cells. When the connection to the coelom was lost an alternative duct system, the parmesonephric ducts were developed to provide passage for the germ cells. In external fertilization both eggs and sperm are shed into water and fertilization, development, and growth of the zygote all take place outside the body.
Internal fertilization occurs when egg and sperm are joined inside of the body. The zygote can develop inside of the reproductive tract, as in mammals. Birds and reptiles have internal fertilization but lay eggs. The zygote develops inside the egg but outside of the body. Invertebrates that have internal fertilization also lay eggs.
The Excretory System Vertebrates have a closed circulatory systemwhich means that they have arteries and veins that transport blood.
Cellular metabolism produces waste and uses nutrients and water. The circulatory system carries water and nutrients to cells and carries waste products away from cells. Water and nutrients come from ingestion and digestion. Waste removal is critical to maintaining internal homeostasis.
Nitrogen is the most toxic byproduct of cellular metabolism.
Introductory Anatomy: Excretory & Reproductive Systems
The body must excrete nitrogen. Nitrogen is commonly produced as ammonia from cells. Many animals will convert ammonia, which is extremely toxic, into a less toxic form of nitrogenous waste.
These include urea and uric acid. The habitat of an animal determines which kind of nitrogenous waste it produces. Most aquatic animals, both invertebrates and freshwater fish, excrete ammonia.
Ammonia dissolves in water and is easy to transport outside of the body by diffusion when an animal is surrounded by water. This happens primarily through the skin in invertebrates and through the gills of fishes. Ammonia must be diluted by a great deal of water to be nontoxic.
There is not enough water in land animals to dilute ammonia enough, so ammonia is turned into either urea or uric acid.
Which of these an animal produces is linked to where the offspring develop. Animals characterized by internal development of offspring such as mammals make urea. So do animals that have eggs which develop in water, such as amphibians, sharks, and some fish that live in saltwater.