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Development of the kidney
Last reviewed: 23.04.2024
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The kidney develops from the middle germinal leaf (segmented legs - nephrotoplasms) in the form of three consecutive pairs of pads: the preference, the primary kidney and the terminal kidney.
The preeclamps (anterior, or head, kidney) is laid in the embryo of the person at the 3rd week of embryonic development from the nephrotopathomas of the lower cervical and upper thoracic segments (mesoderm in the area of the somite transition into the lateral plates) and consists of 5-8 tubules. The tubules of preference have a short period of development (there are 40-50 hours), and then completely reduced. The inferior duct of the preference is preserved and becomes the duct for the next generation of the kidney, the primary kidney.
Primary kidney (mesonephros); (middle kidney, trunk kidney, volphic body) begins to develop in the human embryo at the end of the 3rd week from the nephritoma of the thoracic and lumbar segments and consists of 25-30 segmental convoluted tubules. The blindly beginning end of each tubule widens and forms a capsule (a double-walled glass) into which the vascular glomerum is invaginated. As a result, a kidney body is formed. The other end of the tubule opens into the excretory duct of the preference, which becomes the duct of the primary (middle) kidney (ductus mesonephricus). The primary kidney develops in the region of the posterior wall of the body cavity, being part of the longitudinal elevation - the urogenital fold (plica urogenitalis).
The primary kidney is the first secretory organ that functions in the human embryo during the 1st and 2nd months of embryonic development. At the end of the second month, a partial reduction of the tubules of the primary kidney occurs and it ceases to function. Of the preserved tubules of the primary kidney and the duct of the primary kidney, the epididymis and the vas deferens are formed in the male and the ovaries in the female. In place of the primary kidney is the third generation of urine-forming organs - the final kidney.
The final kidney (metanephros; permanent kidney, pelvic kidney) occurs in the embryo of the human on the 2nd month of embryonic development caudal to the primary kidney (in the pelvic region) from two sources: from metanephrogenic tissue and the proximal end of the ureteral outgrowth of the primary kidney duct. From the fusion of these two tabs and the tubular system developing in them, the cortical and medullar substance of the kidney forms, while the metanephrogenic tissue first concentrates near the ureteral outgrowth that grows into it. During the growth and branching of the ureteral outgrowth, its proximal end widens, becoming a rudiment of the ureter, renal pelvis, kidney cups and collecting renal (urinary) tubules. Collecting tubules with their branching overgrown with metanephrogenic tissue, through which the kidney tubules (tubules of the nephron) are formed. Beginning with the 3rd month of embryonic development, the final kidney replaces the primary kidney. Development of the final kidney ends only after birth. In the process of development of the final kidney, the kidney ascends to the future lumbar region due to the uneven growth of the body segments. The ureter forms from the ureteral outgrowth of the primary kidney duct.
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