The main difference between mesonephric and metanephric kidneys is that the mesonephric kidney is the kidney occurring in adult higher fish, amphibians, and embryogenesis in mammals, whereas the metanephric kidney is the embryogenic organ that forms the permanent kidney in mammals.
Mesonephric and metanephric kidneys are two types of kidneys that occur in vertebrates during different development stages of animals. These kidneys are functional during embryonic development.
Key Areas Covered
1. What is Mesonephric Kidney
– Definition, Structure, Function
2. What is Metanephric Kidney
– Definition, Structure, Function
3. Similarities Between Mesonephric and Metanephric Kidney
– Outline of Common Features
4. Difference Between Mesonephric and Metanephric Kidney
– Comparison of Key Differences
Key Terms
Mesonephric Kidney, Metanephric Kidney
What is Mesonephric Kidney
The mesonephric kidney is one of the three types of kidneys developing in vertebrates. It serves as the main excretory organ of aquatic vertebrates. In addition, the mesonephric kidney is the temporary kidney for birds, reptiles, and mammals. In mammals, it develops into a metanephric kidney after embryogenesis. The three types of kidneys in development are pronephros, mesonephros, and metanephros. Generally, the earliest and the most primitive type of kidney is the pronephros. It is functionally active in lower vertebrates during development.
Figure 1: Mesonephric Ducts
Furthermore, pronephros includes simple tubules that empty into the primary nephritic duct. Later, pronephros degenerates, developing mesonephros along the nephritic duct. However, mesonephros is more complex, and it contains a glomerulus and structures like a proximal tubule. In general, mesonephros in mammals develops into metanephros. However, mesonephros occurs and functions between the sixth and tenth weeks of embryological life.
What is Metanephric Kidney
The metanephric kidney is one of the three embryonic organs in mammals forming the permanent kidney. It develops from the mesonephric kidney. The origination of the metanephric kidney occurs from two structures: the ureteric bud (UB) and the metanephric mesenchyme (MM). Here, the ureteric bud branches from the nephric duct, while the metanephric mesenchyme is a region of intermediate mesoderm. Meanwhile, the development of the ureteric bud occurs during the fifth week of gestation. Another name for the ureteric bud is the meta nephrogenic diverticulum. During the development of the metanephric duct, the ureteric bud forms the renal pelvis and the major and minor calyces.
Figure 2: Metanephric Kidney
Moreover, the tips of the ureteric bid branches are in contact with the undifferentiated intermediate mesoderm. Generally, these regions are known as meta nephrogenic blastema. They differentiate into renal tubules. The renal tubules also develop coming into contact with connecting tubules of the collecting duct system. This forms a continuous passage for the flow from the renal tubule to the collecting duct.
Similarities Between Mesonephric and Metanephric Kidney
- Mesonephric kidney and metanephric kidney are two types of kidneys that occur in vertebrates during different stages of life.
- These kidneys are functional during embryonic development.
Difference Between Mesonephric and Metanephric Kidney
Definition
The mesonephric kidney refers to an embryonic organ that disappears in all mammalian species when the permanent kidney, the metanephros, is functional, while the metanephric kidney refers to a highly complex organ that filters waste products from the circulation and maintains electrolyte and pH.
Occurrence
The mesonephric kidney occurs after pronephros, while the metanephric kidney occurs after mesonephros.
Importance
The mesonephric kidney occurs in adult higher fish, amphibians, and mammals only during embryonic development, while the metanephric kidney occurs in mammals.
In Mammals
Mesonephric kidney occurs during embryogenesis in mammals, while metanephric kidney becomes permanent kidneys in mammals.
Conclusion
In brief, mesonephric and metanephric kidneys are two types of kidneys that occur during the embryonic development of vertebrates. Generally, the mesonephric kidney develops from pronephros in higher adult fish and amphibians. It occurs in mammals during embryogenesis. In comparison, the metanephric kidney is the type of kidney that develops into a permanent kidney in mammals. Therefore, the main difference between mesonephric and metanephric kidneys is their occurrence.
References:
- Rumballe B, Georgas K, Wilkinson L, Little M. Molecular anatomy of the kidney: what have we learned from gene expression and functional genomics? Pediatr Nephrol. 2010 Jun;25(6):1005-16. doi: 10.1007/s00467-009-1392-6. Epub 2010 Jan 5. PMID: 20049614; PMCID: PMC3189493.
Image Courtesy:
- “Gray1107” By Henry Gray – Own work (Public Domain) via Commons Wikimedia
- “Development of embryonic nephrons” By Ashley Sawle – Own Work (CC BY-SA 3.0) via Commons Wikimedia
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