Development of female external genitalia

1. • The main structures of the female external genitalia are:
• Mons pubis: an anterior thick skin fold having a collection of subcutaneous
fat and hair part.
• Labia majora: two rounded thick skin folds one on each side having a
collection of subcutaneous fat hairy the space between these folds is called
pudendal cleft.
• Labia minora: two thin skin folds one on each side the space between
these folds is called vestibule of vagina.
• Clitoris: it resembles the penis in male it is in the anterior part of pudendal
cleft it consists of two corpora cavernosa (forming the body of clitoris)
which enlarge anteriorly to form glans clitoris.
Development of female external genitalia

3. • the external genitalia of males and females look the same, and follow
a common development.
• This includes the development of a genital tubercle and a membrane
dorsally to it, covering the developing urogenital opening, and the
development of the labioscrotal fold, also called the urogenital fold,
and the labioscrotal swelling.
Indifferent stage:
• Cranial to the cloacal membrane, the folds unite to form the genital
tubercle.
• Genital (labioscrotal) swellings arise lateral to the urogenital folds.
• The overlying urogenital (cloacal) membrane becomes perforated in
the urethral groove to form urogenital orifice.

5. Common development
• Urogenital membrane
- initially a cloacal membrane, composed of ectoderm and endoderm,
reaching from the umblical cord to the tail.
- After the separation of the rectum from the dorsal part of the cloaca,
the ventral part of the cloacal membrane becomes the urogenital
membrane.

6. . Phallus
The genital tubercle develops into the phallus, the first rudiment of
the penis or clitoris.
• Genital tubercle
Mesoderm extends to the midventral line for some distance behind the
umbilical cord, and forms the lower part of the abdominal wall; it ends
below in a prominent swelling, the cloacal tubercle, which after the
separation of the rectum become the genital tubercle results from
mesenchymal proliferation .

7. • Urogenital folds (=genital fold= urethral fold)
The primary urethral (urogenital) folds surround the primary urethral
groove.
. Labioscrotal swellings (= genital swellings):
- The genital or labioscrotal swellings formed lateral to the urethral
folds.
- They are paired structures in the human embryo that represent the final
stage of development of the caudel end of external genitalia before sexual
differentiation in both males and females.

9. • Differentiation of external genitalia:
- Mons pubis: the folds (labioscrotal fold) fuse anteriorly
to form the mons pubis.
- Phallus: will form clitoris.
- Genital folds: will form labia minora.
- genital swelling: will form labia majora.