Urogenital System

  • Briefly describe development of the metanephric kidney system
    • The Ureteric bud elongates and penetrates the metanephric blastema
    • Reciprocal induction between the ureteric bud and metanephric blastema forms the permanent kidneys
      • Stalk of the ureteric bud β†’ ureter
      • Cranial part of ureteric bud β†’ collecting tubules, major calices, minor calices
      • Metanephrogenic blastema β†’ nephron
  • State the embryological basis for the following anomalies: multicystic dysplastic kidney, duplication of the ureter, accessory renal artery, horse-shoe shaped kidney, pelvic kidney
    • Multicystic dysplastic kidney
      • Dysmorphology of the renal system
    • Duplication of the ureter
      • The ureteric bud divides abnormally
    • Accessory renal artery
      • The renal arteries perisist as the kidney ascends the pelvis
    • Horse-shoe shaped kidney
      • The migration of nephrogenic cells is impaired causing the inferior poles of the kidneys fuse
    • Pelvic kidney
      • The Kidney fails to ascend from the pelvis
  • Briefly describe the development of the adrenal gland and state an associated congenital anomaly Development
    • Mesenchyme β†’ Develops into the adrenal cortex
    • Neural Crest cells β†’ Develop into the adrenal medulla
    • Neural crest cells form a mass on the medial side of the embryonic cortex and differentiate into secretory cells of the medulla
    • The medulla is surrounded by the cortex
    • More mesenchymal cells arise from the mesothelium and enclose the cortex, forming the permanents cortex of the adrenal gland
    Congenital anomaly
    • Congenital Adrenal Hyperplasia and the adrenogenital syndrome
  • Briefly describe the development of external genitalia in both sexes Male
    • Testosterone β†’ is resonsible for the masculinization of the indifferent external genitalia
    • Primordial phallus β†’ elongates to form the penis
    • Urethral folds β†’ fuse to form the spongy urethra on the ventral penis
    • Surface ectoderm β†’ fuses in the median plane to form the penile raphe
    • Ectodermal cord β†’ grows towards the root of the penis and meets the spongy urethra, canalizes and completes the external urethra orifice
    • Phallic mesenchyme β†’ corpus cavernosum and corpus spongiosum
    • Labioscrotal swellings β†’ scrotum
    Female
    • Primordial phallus β†’ clitoris
    • Urethral folds β†’ fuse posteriorly to form the frenulum of the labia minora
    • Unfused part of urogenital folds β†’ labia minora
    • Fused labioscrotal folds β†’ fuse to form posterior and anterior labial commissure and mons pubis
    • Unfused labioscrotal folds β†’ labia majora
  • Briefly describe the development of the genital ducts in both sexes Male
    • Mesonephric ducts β†’ male genital ducts
    • Proximal mesonephric duct β†’ epididymis
    • Persistent mesonephric tubules β†’ efferent ductules
    • Distal mesonephric duct β†’ vas deferens after acquiring smooth muscles
    • Caudal mesonephric duct β†’ seminal vesicles
    • Mesonephric duct between the duct of the seminal gland and urethra β†’ ejaculatory duct
    • Endoderm of the prostatic urethra β†’ glandular epithelium of prostate
    • Endoderm of the spongy urethra β†’ bulbourethral gland
    Female
    • Mesonephric duct β†’ degenerates because of low testosterone
    • Paramesonephric duct β†’ develop because of the absence of MIS
    • Cranial paramesonephric duct β†’ uterine tubes
    • Caudal fused paramesonephric duct β†’ uterovaginal primordium
    • Uterovaginal primordium β†’ uterus and vagina
    • Splanchnic mesenchyme β†’ endometrial stroma and myometrium
  • Briefly describe the development of the gonads in both sexes Male
    • Testis determining factor – induces testes formation
    • MIS β†’ suppresses paramesonephric duct formation
    • Seminiferous cords β†’ rete testis, seminiferous tubules, tubules recti (straight tubules)
    • Mesenchyme separating the seminiferous tubules β†’ intersitial cells of leydig
    • Surface epithelium of testis β†’ sertoli cells
    • Primordial germ cells β†’ spermatozoa
    Females
    • Gonadal cords β†’ rete ovarii
    • Cortical cords β†’ primordial follicles
    • Primordial germ cells β†’ oogonia

Distinguish between hermaphrodites and pseudohermaphrodites

HermaphroditePseudohermaphrodite
DefinitionHave gender ambiguous genitalia – both male and female genitaliaGonads are consistent with the chromosomal sex, Genitalia are of the opposite sex
CausesNot associated with disease5-alpha reductase deficiency, Androgen insensitivity syndrome
Dr Jeffrey Kalei
Dr Jeffrey Kalei

Author and illustrator for Hyperexcision. Interested in emergency room medicine. I have a passion for medical education and drawing.

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