Difference between metanephric kidney and opisthonephric kidney?
Metanephric kidney and opisthonephric kidney represent two distinct types of kidneys found in vertebrates. They differ in their structure, location, and functional characteristics:
1. Metanephric Kidney:
a. Structure: Metanephric kidneys are the most advanced and efficient type of kidneys found in mammals, birds, and some reptiles. They consist of two bean-shaped structures located in the abdominal cavity.
b. Location: Metanephric kidneys are located higher up in the body compared to opisthonephric kidneys. In mammals, they are situated near the lumbar region close to the adrenal glands.
c. Function: Metanephric kidneys are highly specialized in filtering waste products, regulating electrolyte balance, and controlling water reabsorption. They produce concentrated urine, allowing for efficient conservation of water.
d. Nephrons: Metanephric kidneys have numerous nephrons, which are the functional units responsible for urine production. Each nephron consists of a glomerulus, proximal tubule, loop of Henle, and distal tubule, all essential for various filtration and reabsorption processes.
2. Opisthonephric Kidney:
a. Structure: Opisthonephric kidneys are found in some fish, amphibians, and reptiles. They appear as long, ribbon-like structures extending along the dorsal body wall, closely associated with the vertebral column.
b. Location: Opisthonephric kidneys are situated in the posterior (back) region of the body, hence the term "opistho" (meaning "behind"). They are located near the reproductive organs and the cloaca.
c. Function: Opisthonephric kidneys are responsible for regulating internal fluid balance, electrolyte concentrations, and waste elimination. They produce less concentrated urine compared to metanephric kidneys.
d. Nephrons: Opisthonephric kidneys have fewer nephrons than metanephric kidneys. Each nephron contains a renal corpuscle, proximal tubule, and distal tubule. The loop of Henle, a specialized region for water and ion reabsorption, is either short or absent in the nephrons of opisthonephric kidneys.
In summary, metanephric kidneys are highly developed and specialized kidneys with efficient filtering capabilities and sophisticated nephron structures. They are found in advanced vertebrate groups, such as mammals and birds. In contrast, opisthonephric kidneys are less complex kidneys with fewer nephrons and are found in certain fish, amphibians, and reptiles.