Development of the Male and Female reproductive tracts Flashcards
What is the default developmental state for the reproductive system?
Female (lack of Y chromosome and its gene products - form an ovary)
What are the three tissue sources from which the gonads (testicles and ovaries) develop?
- Gonadal ridge (raised region of intermediate mesoderm)
- Mesodermal epithelium (covers the future post abdo wall)
- Primordial germ cells (induce develop of indifferent gonad)
In a developing male, expression of which protein causes the indifferent gonad to become a testicle?
Testis Determining Factor (TDF) - gene on the Y chromosome.
Testosterone secretion by week 8 influences further sexual differentiation of the genitalia
What is Androgen insensitivity syndrome (AIS)?
Results in a genetic male with normal female appearance
Testicles are present and the vagina ends as blind poucha
How do the gonads descend to their adult position?
- Gubernaculum - guides descent of gonads
- Processus vaginalis - forms the inguinal canal
Both structure guide testicle through inguinal canal
What are the two conditions that can be caused by maldescent of the testes?
1.Cryptorchidism (surgical intervention?)
Most often located in inguinal canal (IC)
Many undescended testes appear by 3 months post birth
Inc risk of testicular cancer
2.Ectopic testicle
Testicle transverses IC but ends up not in the scrotum (post abdo wall)
In the female, what normally happen to the processus vaginalis? What happens if it persists?
In females, the processus vaginalis is small and normally regresses.
It’s persistence is known as a persistent processus or the peritoneum (canal of Nuck)
In females, where do the descent of the ovaries stop?
Ovaries stop in the pelvic cavity at the broad ligament (double layer peritoneal fold covering the uterus and uterine tubes - mesentery)
What happens to the female gubernaculum? (hint - persists and attaches to…)
Persists and attaches from the:
- Ovary to uterus (ovarian ligament)
- Uterus to labia (round ligament of uterus)
Why is the round ligament important to consider as a potential pathway for metastatic spread of cancer?
Because it contains lymphatics and vasculature
What are the two pairs of genital ducts that develop in males and female?
Mesonephric (Wolffian) ducts - develop in Male (M)
Paramesonephric (Mullerian) ducts - develop in female
What happens to the mesonephric duct in males and females?
Males: Testosterone production drives the development of the mesonephric duct (week 8) forming the epididymis, ductus deferens, ejaculatory duct and seminal vesicles.
Females: degenerates spontaneously in the absence of testosterone
What happens to the paramesonephric duct in males and females?
Males: Antimullerian hormone production by testicular sertoli cells causes paramesonephric duct regression (week 6-7)
Females: Persists and further develop in the presence of antimullerian hormone - forms the uterine tubes and join in the inferior midline to form the uterus and upper vagina
In males, what is the remnant of the paramesonephric duct called?
Appendix of testicle (can be seen in an ultrasound)
What can happen as a result of uterine and vaginal malformations?
Primary amenorrhoea, subfertility or problematic pregnancy
What are the different types of uterine malformations?
Fundus remodelling Unicorn uterus Didephlic uterus (duplicate) Partial fusion - septum present Large septum present
Complete the sentence:
The paramesonephric ducts form via a process of invagination of the …
The paramesonephric ducts form via a process of invagination of the coelomic epithelium (the future peritoneum)
Describe the formation of the uterus and uterine tubes.
Paramesonephric ducts -> move to midline and fuse. Unfused L and R ends make the uterine tubes. The end of the tubes stay open and communicate with the peritoneal cavity, where ovulation takes place.
Infection can spread from the vagina into the peritoneal cavity
What are the two remnants of the mesonephric ducts?
- Epoophoron or Appendix Vesiculosa - persist around the ovary or lateral to the uterus (paraovarian cyst)
- Gartner’s ducts - around vaginal wall
Both may develop cysts
What is the Hydatid?
A cranial remnant of the paramesonephric duct which can persist as a hydatid (of Morgagni)
What two parts is the cloaca divided into? What are there two parts divided by?
Urogenital sinus (anterior)
Rectum (posterior)
Divided by the urorectal septum
What is the perineal body and why is it important?
Key point of union between pelvic floor and pelvic membrane
Integrity and support of pelvic floor and post vaginal wall
Attachment point for anal sphincter
Usually, tubular structures will start of filled with cells and later canalise, what is this process called? What can go wrong? Name an example in a neonate
Recanalization - tubes will open again by apoptosis
Stenosis due to partial recanalization
Atresion due to no recanalization
Anal atresion in a neonate
What embryological structures does the vagina develop from?
- Uterovaginal primordium (inferior part of the paramesonephric duct)
- Sinovaginal bulb of urogenital sinus
If the solid vaginal plate fails to recanalize to form the vaginal lumen, what happens?
- Vaginal atresia
2. Partial recanalization can produce transverse vaginal septa
Should the hymen be partially open (perforated) in utero or not? What are the abnormal conditions with the hymen?
Yes - it should be partially perforated.
- Imperforate
- Septum remains
- Cribiform septum
- Adult state - majority of hymen gone
List what the below embryological features would develop into in males and females.
- Urogenital/urethral fold
- Labioscrotal swelling
- Genital tubercle
Males:
- Spongy Urethra
- Scrotum
- Penile glans and erectile tissue
Females:
- Labia minora
- Labia majora
- Clitoris
What is the difference between hypospadias and epispadias? Which is more common?
Hypospadias - urethral opening on ventral side of penis (More common)
Epispadias - urethral opening on dorsal side of penis
Which hormones causes the indifferent external genitalia to develop into male external genitalia?
Testosterone
