Describe the contribution of the pronephros, mesonephros and metanephros to the permanent kidney and urinary tract.
- Pronephros: At the beginning of the fourth week, a temporary/transient/vestigial kidney system is set up
- - By the end of the fourth week, all indications of the pronephric system have disappeared.
- Mesonephros: another temporary/transient/vestigial kidney system
- - First excretory tubules appear in the early in the fourth week of development, during regression of the pronephric system
- - In the male, a few of the caudal tubules of the mesonephric duct persist and participate in formation of the genital system, but they disappear in the female.
- - ureteric bud (future adult renal pelvis) forms from branch of the mesonephric duct. The bud dilates, forming the primitive renal pelvis, and splits into cranial and caudal portions, the future major calyces
- Metanephros: permanent kidney which appears in the fifth week.
- - Its excretory units develop from metanephric mesoderm in the same manner as in the mesonephric system. The development of the duct system differs from that of the other kidney systems