Flashcards in Development and Sexual Differentiation of the Reproductive System Deck (43):
What is the 'mesonephros' in foetal development?
It is the tissue that will later form the kidneys later in development
What are gonadal ridges and where are they found?
They are masses of mesoderm which form bulges on the abdominal wall (medial to mesonephros) which eventually forms the testes or ovaries
At which stage of development are foetus' sexually indifferent?
What are Müllerian ducts?
Tissue that will differentiate into oviducts in females, and these develop laterally to the Wolffian ducts and are paramesonephric
What are the Wolffian ducts?
These ducts will develop into the vas deferens in males and this is a mesonephric tissue
What is the common cloaca?
This is a structure that is present at the sexually indifferent stage of development, whereby both the Urogenital and GI systems feed into a common tract
At what week of development does sexual differentiation begin?
Describe the beginning of male sex differentiation
The seminiferous tubules form in the gonadal ridge and then join the Wolffian duct (which eventually becomes vas deferens). The testes have begun to develop and secrete anti-Müllerian hormone to cause the degeneration of the Müllerian ducts
Describe the beginning of female sex differentiation
Müllerian ducts start to differentiate into the oviducts, the Wolffian ducts degenerate.
Describe the descent of the ovaries in female sex differentiation
The ovaries descend on the gubernaculum from the posterior abdominal wall to the pelvic brim, where the descent is then stopped by the presence of the broad ligament
Describe how the gubernaculum in ovarian descent differentiates into two different ligaments
The descent is stopped by the presence of the broad ligament, and this causes the cranial gubernaculum to become the ovarian ligament and the caudal gubernaculum to become the round ligament
What is the inguinal canal?
This structure is approximately 4cm long and it begins at the deep inguinal ring and emerges at the superficial inguinal ring
How come both genders have an inguinal canal?
Due to the presence of a sexually indifferent stage in development
Describe the development of the inguinal canal
A gubernaculum descends on each side of the abdomen from the inferior pole of the gonad, then travels obliquely through anterior abdominal wall, and attaches caudally to the internal surface of the labioscrotal swellings
What is meant by the 'labioscrotal swelling'
The tissue that will eventually become either the scrotum or labia majorum
What is the processus vaginalis?
This is an invagination of the peritoneum which develops anterior to the gubernaculum, and then herniates through the abdominal wall along the path formed (by gubernaculum). This structure carries extensions of the layers of the anterior abdominal wall (which form walls of inguinal canal)
When does gonadal development begin?
Week 5 of development (masses of mesoderm, AKA gonadal ridges)
When do the testes begin to descend?
Around 26 weeks or 7 months
Describe the function of the gubernaculum in the descent of testes in a male
Gubernaculum is attached to the testes and the inferior pole of the scrotum (swelling) and works to pull the testes down from peritoneum into scrotum. Vas deferens descends alongside as well as neurovascular supply from posterior abdominal wall.
What is cryptorchidism?
Known as hidden testes, when the testes haven't descended at birth and remain within peritoneum
What are ectopic testes?
Very rare condition when the gubernaculum doesn't attach to base of scrotum swelling, but does so elsewhere
What is a congenital inguinal hernia (indirect)?
If space between tunica vaginalis and peritoneal cavity fails to close, persistent processus vaginalis exists and a loop of intestine may herniate through this region, passing through deep inguinal ring to inguinal canal
What is hydrocele?
when the vaginal process (males) remains open, but is too small to allow herniation, but there is accumulation of peritoneal fluid in either spermatic cord or testes
Describe the arterial supply to the testes
Testicular artery arises from abdominal aorta
Describe the venous drainage of the testes
By testicular vessels, the left hand side feeds into the left renal vein, whereas the right side drains into the inferior vena cava
Describe the path of the vas deferens
Part of spermatic cord, so passes through inguinal canal --> runs on lateral pelvic wall (covered by peritoneum) --> crosses external iliac vessels --> crosses ureter --> reaches spine --> descends behind bladder --> dilated ampulla of vas then joined by seminal vesicles at common ejaculatory duct
Describe the seminal vesicles
coiled sacs part of the distal part of the vas deferens. which is separated from rectum (which lies posterior to vesicles) by the rectovesical fascia and rectovesical pouch
Why don't vasectomies work immediately?
Still sperm stored in seminal vesicles so potential for fertility 3-6 months later
Describe the structure of the prostate
Lies below the bladder on the pelvic floor and consist of 1 median and 2 lateral lobes - transversed by urethra and ejaculatory duct
What might prostatic hypertrophy indicate?
Usually growth of the median lobe which disturbs vesicular sphincter action, so urinating is difficult. However, if there is growth of the lateral lobes this is likely to be indicative of cancer of the prostate and will be palpable upon rectal examination
What may cause the development of a double, bicornuate or unicornuate uterus?
Incomplete fusion of the mullerian ducts inferiorly, incomplete development of the ducts, failure of one of the ducts.
What are the three main ligaments of the uterus?
Ovarian ligament (ovary to uterus), round ligament (uterus to labium majorum) and broad ligament (sheet of peritoneum acting as suspensory ligament)
How are the ovaries attached to the broad ligament?
At the back by the mesovarium
Name the 5 structures which support the uterus
1) Levator ani muscle (pelvic floor)
2) Perineal body (insertion point of many support muscles)
3) Transverse cervical ligaments (lateral pelvic walls to cervix and upper vagina)
4) Pubocervical ligaments (two bands of CT from pubis to cervix)
5) Sacrocervical ligament (cervix to sacrum)
Name the two peritoneal pouches in a female
Vesicouterine pouch (between bladder and uterus) and rectouterine pouch (pouch of Douglas)
Where would you find the vesicouterine pouch?
Space between the uterus and the bladder
Where would you find the pouch of Douglas?
Between the uterus and the rectum (also known as rectovesical pouch, as in males this would have the seminal vesicles here)
Describe the structure of the vagina
Upper half is above pelvic floor and low part is within perineum
Describe the fornices of the vagina
Anterior fornix: bladder and urethra here
Posterior fornix: pouch of Douglas
Lateral fornix: ureters, levator ani, urogenital diaphragm and bulb of vestibule
Describe the support of the upper vagina
Transverse cervical, pubocervical and sacrocervical ligaments
Describe the support of the middle vagina
Levator ani muscles and urogenital diaphragm
Describe the support of the lower vagina
Perineal body action