UNSW Embryology

E6: R,L adrenal glands under diaphragm.

E7: Large adrenal glands. Inferior vena cava. Thoracic aorta.

Fl: Adrenal glands. R. Kidney. Autonomic ganglia (partly the adrenal medulla precursors).

F2: Kidneys (note retroperitoneal location). Cortex. Medulla. L. Adrenal gland. Superior mesenteric artery. Inferior vena cava.

F3: R testis (note its location relative to the R adrenal). L adrenal. R renal hilus. large channels are branches of ureteric tree.

F4: R kidney and R ureter. Inferior vena cava. L. kidney, L renal hilus and L ureter. R testis with R mesonephric duct (precursor of vas deferens). L testis. Umbilical arteries passing into umbilical cord allantois between them.

F5: Kidneys. Ureters. Note umbilical arteries and allantois. Also note how R testis and mesonephric structures are attached to parietal peritoneum by a mesogonad.

F6: Kidneys. Ureters. Note umbilical arteries and allantois. Also note how R testis and mesonephric structures are attached to parietal peritoneum by a mesogonad.

F7: In F7, (dorsal to R testis and liver) note with the distinct lumen of the mesonephric duct, almost solid column of paramesonephric cells and remnants of mesonephric tubules. "mesogonad". Ureters. Bladder with submucosa and detrusor muscle. Umbilical arteries. Division of aorta.

G1: Ureters, Bladder. Umbilical arteries. Testis with remains of mesonephros (dorsal), mesonephric duct and paramesonephric cells. Sigmoid colon and mesocolon.

G2: Ureters being displaced ventrally, crossing common iliac arteries. Sigmoid colon. Bladder. Mesonephric ducts (lateral) and paramesonephric ducts (smaller, medial) located dorsal to bladder.

G3: Ureters (cut twice): descending dorsal to bladder and ascending ventrally to enter the bladder at trigone, through the submucosa). Fusion of paramesonephric ducts. Paired mesonephric ducts. Umbilical arteries looping off common iliac arteries. Pubic symphysis. Colon.

G4: Most caudal part of loop of ureters. Urethra emerging from bladder. Mesonephric ducts. Rectocolic junction.

G5: Urethra (in region of future prostate gland - note crescentic shape). Rectum. Rectovesical pouch. Between G4 and G5, each mesonephric duct (vas deferens) has joined the prostatic urethra (caudal to the ureters), thereby increasing the caliber of the latter.

G6: Penile urethra, emerging inferiorly to the glans penis. Scrotal swellings (appear before testis descends).

G7: Penile urethra, emerging inferiorly to the glans penis. Scrotal swellings (appear before testis descends).

Note F7 MS term: "inebriated Puffin" (dorsal to R testis and liver) lumen of the mesonephric duct (eye), almost solid column of paramesonephric cells (beak) and remnants of mesonephric tubules (body).

Stage 22 Embryo (Human) Genital System (Male) (also see Female)

F3: R testis with thick tunica albuginea (pale) and thin urogenital mesentery.Note spleen on L.

F4: Testes. Narrow urogenital mesentery. Remains of mesonephric tubules near hilus (future efferent ductules at mediastinum testis).

F5: Broader urogenital mesentery on R (still narrow on L).

F6: On R: Remnants of mesonephric tubules (primordia of ductuli efferentes). Mesonephric duct (origin of vas deferens). Laterally, the paramesonephric duct (primordia of appendix testis). Note abdominal location of testes in relation to adjacent structures.

F7: Developing efferent ductules, mesonephric duct and medially, the paramesonephric duct (appearing solid). Note how the paramesonephric duct crossed the mesonephric duct ventromedially. Urogenital mesentery - note how testis is attached to the developing efferent ductules by a separate narrow flange,the mesorchium.

G1: On R: Lateral mesonephric duct and medial paramesonephric groove. (Changing from a tube to a groove). On L: testis (lower than on R), mesonephric tubules, mesonephric duct (lateral), paramesonephric duct (ventromedial - appearing solid).Bladder. Umbilical arteries. Sigmoid colon and mesocolon.

G2: Transition from abdominal cavity to superior pelvis. note iliac crest, femoral nerve, psoas major muscle, internal iliac vein and artery. Medial convergence of paramesonephric cords and more laterally-located mesonephric ducts, ventral to the colon and dorsal to the bladder. Note position of ureters. N.B. Testis lies above this level which is close to the plane of the future inguinal canal.

G3: Transition from superior (major) pelvis to inferior (minor) pelvis. Rectovesical pouch. Note wide expanse of loose tissue ventral to the pubic symphysis: site of testicular descent.

G4: Transition from superior (major) pelvis to inferior (minor) pelvis. Rectovesical pouch. Note wide expanse of loose tissue ventral to the pubic symphysis: site of testicular descent.

External genitalia (male)
G5: Minor pelvis. Obturator foramen. Ischium. Head of femur. Acetabulum. Ganglion cells of pelvis plexus. Obturator externus muscle. Urogenital sinus (the caudal enlargement is due to junction of mesonephric ducts).

G6:Level of pelvic floor. Pelvic plexus. Recto-anal junction. Ischium. obturator internus muscle. Greater sciatic notch. Alar of sacrum. Sacro-iliac joint.

G7: Urethra opening ventrally. Genital tubercle (embryonic glans penis).

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