Evolution of Urinogenital Duct

Evolution of Urogenital Duct: The urinary system is the excretory system and consists of kidneys and their ducts. The genital system is the reproductive system which consists of testes or ovary and their ducts. Both the urinary duct and the genital duct are united to form the urogenital duct. Through the urogenital duct both the urine and the sperms are released. The urogenital ducts are different in females and males so for our convenience it can be grouped as: Female urogenital duct Male urogenital duct Female Urogenital Duct: The urogenital duct consists of a pair of oviduct that extends from ostia and to cloaca. Different parts of the oviduct perform special functions like fertilization, implantation, etc. Different vertebrates have the following urogenital ducts which are evolutionarily arranged in a different succession: Cartilaginous: In cartilaginous fish, two ostia are fused to form a single ostium both. Both the oviduct are also united to form a common duct. Uterus holds the eggs until laying. The urinary system duct is urethra is united to the uterus through which releases the urine. Bony Fish: In bony fish, both the duct like urinary and genital duct are continuous with the cavity of the ovary and fused to form a common duct. Amphibia: In amphibia, the oviducts are long and convoluted which secret a jelly-like material around the egg. The urinary duct is separated from the oviduct but in later stages united. Reptiles and Birds: In reptiles and birds only one coiled oviduct is present. The oviduct is lined with glands that add albumen, shell, and other pigments. The urinary system is separated but in later part, they are united and release the urine and ovum through a common opening, cloaca. Mammals: In mammals, the oviduct is small, narrow, convoluted, and lined with cilia which prop the ovum and fertilized egg towards the uterus. The urinary system, mainly ducts, are separated and release the urine through the urethral orifice. Male Urogenital Duct: In male different animals, vertebrates also possess the following urogenital ducts: Cartilaginous Fish: In cartilaginous fish, the anterior part of the mesonephric duct carries only sperm and the posterior part of the nephric tubule is separated to release the urine. Bony Fish: In bony fish, the mesonephric duct is primarily used for the transport of sperm and the accessory urinary duct transports the urine. Reptiles and Birds: In reptiles and birds, the urinary and genital ducts are separated but in later stages both are united at the cloacal region. Mammals: In mammalian males, the urinary duct (urethra) and the genital duct communicate with the urethra, so urethra is the common passage for the release of urine and sperm. The urinary system, mainly duct are separated and release the urine through the urethral orifice. Male genital duct: In male different animals vertebrates also possess following urinogenital duct. Cartilaginous fish: In cartilaginous fish, the anterior part of the mesonephric duct carries only sperm and the posterior part of the nephric tubule is related for release of urine. Bony fish: In bony fish the mesonephric duct is primarily used for transport of sperm and the accessory urinary duct transports the urine. Reptiles and birds: In reptiles and birds the urinary and genital ducts are separated but in later stage both are united at the cloacal region. Mammals: In mammalian male the urinary duct urethra and the genital duct communicate with the urethra. So urethra is the common passage for the release of urine and sperm. Describe different types of uterus The uterus are mainly found in mammals. It is the organ for implantation and the development of foetus up to gestation period. It is also the site for periodic loss of mucus or blood. Following four types of uterus are found: Duplex: In duplex uterus, there are two uteri and two cervices. It is found in Lagomorpha. Bipartite: In this case, there are two uteri but only one cervix. It is found in carnivores and cetaceans (whale, dolphin). Bicornuate: In this case, the uterus is Y-shaped and separated medially but fused distally to form a common chamber and opens to a single cervix. It is found in insectivores. Simplex: In this case, no partition wall is present and the uterus is single and opens to the vagina through one cervix. It is found in primates.