✅ EMBRIOLOGÍA del SISTEMA URINARIO 💦🚽 | Sistema UROGENITAL
Embryology of the Urogenital System
Overview of the Urogenital System
- The urogenital system consists of organs responsible for waste elimination and reproduction, including urinary and genital organs.
- A dorsal view of an embryo during the third week reveals three types of mesoderm: lateral, intermediate, and paraxial.
Developmental Stages
Formation from Intermediate Mesenchyme
- The urogenital system originates from the intermediate mesenchyme, which is displaced ventrally during embryonic folding. This results in a longitudinal elevation known as the urogenital crest.
Urinary System Development
- The urinary system develops before the genital system and includes kidneys (excreting urine), ureters (transporting urine), bladder (storing urine), and urethra (expelling urine).
Kidney Systems in Embryos
Three Kidney Systems
- Human embryos exhibit three kidney systems:
- Pronephros: Rudimentary with non-functional structures.
- Mesonephros: Well-developed but functional only temporarily.
- Metanephros: Located at pelvic level; these become permanent kidneys.
Pronephros Regression
- By the fourth week, pronephros is represented by compact cell groups forming nephrotomes that regress before more advanced systems develop.
Mesonephric Tubules Formation
- As pronephric regression occurs, mesonephric tubules appear, elongating to form S-shaped structures that create glomeruli surrounded by Bowman's capsule. These structures together constitute renal corpuscles.
Metanephros Development
Origins and Structure
- Permanent kidneys arise from two sources:
- Ureteral outline or metanephric diverticulum.
- Metanephrogen blastema, derived from nephrogenic cord's caudal part.
Branching Processes
- The metanephric diverticulum grows into branches that differentiate into collecting tubules within metanephros leading to major and minor calyces formation.
Nephrons Formation
- Each arcuate collecting tubule induces aggregates in metanephrogen blastema to form small vesicles that elongate into metanephric tubules, ultimately differentiating into nephrons—the basic functional units of kidneys—numbering around one million per kidney at birth.
Kidney Position Changes
- Initially located in the pelvic region, kidneys ascend to a cranial position due to body curvature decrease and growth in lumbar/sacral regions during development.
Bladder and Urethra Development
Cloaca Division
- Between weeks four to seven, cloaca divides into urogenital sinus (anteriorly) and anorectal duct (posteriorly), with urorectal septum forming between them leading to perineal body formation.
Urogenital Sinus Portions
- The urogenital sinus has three parts:
- Bladder portion forms most of bladder.
- Pelvic part becomes urethra/bladder neck.
- Phallic part grows towards genital tubercle.
Urachus Transformation
- Initially continuous with allantois, bladder contracts transforming it into urachus—a fibrous cord represented as middle umbilical ligament in adults after kidney ascent displaces ureter orifices cranially for prostatic urethra penetration in males while degenerating in females.
Epithelium Development
Embryology of the Urogenital System
Development of the Urinary System
- In males, outbreaks related to urogenital development originate in the Prostate Gland.
- In females, these outbreaks begin in the cranial portion of the urethra, leading to the formation of urethral and paraurethral glands.
- Congenital anomalies of the renal system include:
- Renal agenesis
- Duplication of the ureter
- Pelvic kidney
- Cross ectopia
- Horseshoe kidney
- The discussion covers key aspects of embryological development specific to both male and female urinary systems.