Embryology

Question 1

What does Müllerian (paramesonephric) duct differentiate into, and how does it form these structures?

Answer 1

Umlaut = "uu" --> MUU <> FUU
FUU = fallopian tubes, uterus, upper vagina

Bilateral paramesonephric ducts fuse

Question 2

What does Wolffian (mesonephric) duct differentiate into?

Answer 2

SEED: seminal vesicles, ejaculatory duct, epididymis, ductus deferens

+Ureter in both M and F

Question 3

Where do male internal genitalia originate from?

Answer 3

Wolffian duct

[except prostate, which comes from urogenital sinus]

Question 4

Where do male external genitalia originate from?

Answer 4

Genital tubercle (glans of the penis)
Urogenital folds (ventral aspect of penis)
Labioscrotal folds (scrotum)

Question 5

What main cell types make up the indifferent gonad, and what do they differentiate into?

Answer 5

1) Primordial germ cells from yolk sac –> oocytes and spermatozoa
2) Coelomic epithelium –> primitive sex cords –> ovarian follicle cells (granulosa) / seminiferous tubules (Sertoli cells), rete testis
3) Mesenchyme –> Leydig cells, ovary

Question 6

Gubernaculum becomes what in females?

Answer 6

Ligament of the ovary (connecting ovary to uterus)

Round ligament of ovary

Question 7

How does broad ligament form?

Answer 7

As Mullerian ducts descend, they bring their attachments to the lateral body wall with them

Question 8

Urogenital sinus differentiates into?

Answer 8

M: prostate, bladder, urethra, bulbourethral glands
F: lower portion of vagina, bladder, urethra, greater vestibular glands

Question 9

Which embryonic tissue layer do the urogenital organs develop from?

Answer 9

Intermediate mesoderm

Question 10

What tissue structure does the kidney originate from?

Answer 10

Metanephric kidney

Question 11

Relationship between metanephric mesenchyme and ureteric bud

Answer 11

Metanephric mesenchyme induces ureteric bud outgrowth from mesonephric duct. Ureteric bud = collecting duct, major/minor calyces, renal pelvis

Ureteric bud then induces metanephric mesenchyme to undergo mesenchymal to epithelial transition to form nephron (glomerulus through distal convoluted tubules)

Question 12

What positional change occurs between kidneys and gonads during development?

Answer 12

Kidneys ascend (associated with formation of renal ladder) and gonads descend –> “water under the bridge” (ureter under vas deferens, uterine artery)