Reproductive Development Flashcards
During which week do the PGCs invade the genital ridges
6th week
From which layer do the urinary and reproductive systems develop?
Intermediate mesoderm (common mesodermal ridge)
Intermediate mesoderm swell to form what?
Urogenital ridge
The urogenital ridges will swell to form which two ridges?
Genital ridge (medial) and Nephrogenic cord/ridge (lateral)
Test question During which week do gonads acquire male/female morphological characteristics?
7th week
how are the gonadal ridges formed
proliferation of epithelium and condensation of underlying mesenchyme
During indifferent gonad stage which two pairs of ducts are present?
- Mesonephric (Wolffian) ducts
2. Paramesonephric (Mullerian) ducts
Which ducts come together at the midline and what does their caudal tip form?
Paramesonephric ducts; sinus tubercle
Where do the mesonephric (Wolffian) ducts open into?
The urogenital sinus on either side of the sinus tubercle
The Y chromosome houses which gene, and how is this gene responsible for male development?
SRY gene; SRY gene encodes for testis-determining factor (TDF) which leads to development of testis
Longitudinal cords of PGCs are known as what?
Testis (or medullary) cords
What is the dense layer of fibrous CT separating the testis cords from the surface epithelium
Tunica albuginea
The testis cords break up into a network of tiny cell strands that eventually give rise to what?
tubules of rete testis
The testis cords are comprised of what two types of cells?
PGCs and Sertoli cells
where are Sertoli cells derived from?
testis surface epithelium
Which cells lie between the testis cords? what is their function? Derived from?
Leydig cells; begin production of testosterone; mesenchyme of gonadal ridge
In which week is the production of testosterone begun?
8th
At puberty the testis cords acquire a lumen and become what?
Seminiferous tubules
What links the rete testis with the Wolffian duct?
efferent dutules
The mesonephric duct gives rise to what?
Vas deferens
Most of the mesonephric duct persists in males, forming which 5 structures (from proximal to distal to the testis)
- efferent ductules
- Epididymis
- vas deferens (ductus deferens)
- seminal vesicle
- ejaculatory duct
Which cells produce a hormone causing the degradation of the paramesonephric ducts? What are the names of this hormone
Sertoli cells; Anti-Mullerian Hormone (AMH)/Mullerian inhibiting substance (MIS)
In males, what is the small portion of paramesonephric duct that remains?
Appendix testis (at the cranial end)
Where and in what position do the testis develop?
Abdominal region; retroperitoneal
what is the condensation of mesenchyme that anchors the testis to the floor of the scrotum and assists in the descent of the testis?
gubernaculum
What is the evagination of peritoneum from the abdominal cavity that follows the course of the gubernaculum into the scrotal swellings?
processus vaginalis or vaginal process
the testes are covered by _____ of the process vaginalis
reflected folds
As the testis descends thru the inguinal ring, it is covered by the following layers
- Visceral layer of tunica vaginalis (from vaginal process)
- Parietal layer of tunica vaginalis
- Internal spermatic fascia (arises from transversalis fascia
- Cremasteric fascia and muscle (from internal abdominal oblique)
- External spermatic fascia (from the EO)
which of the anterolateral abdominal muscles does not form a layer that covers the testes?
Transversus abdominis
In female development, the primitive (medullary) cords dissociate into what? What part of the ovary do these occupy?
irregular cell clusters; medullary part
In contrast to male development, what happens with the surface epithelium in female development?
Surface epithelium CONTINUES to proliferate
During the 7th week of female development, the surface epithelium gives rise to what cords?
Cortical cords
In what month do the cortical cords split into isolated cell clusters? What do these cell clusters become?
3rd month; follicular cells
What is the primordial follicle?
Oogonium and its surrounding epithelium layer of follicular cells
The presence of ____, and the abscence of ___ & ____ causes _____ to develop into the main female genital ducts
estrogen; testosterone & AMH/MIS; paramesonephric (Mullerian) duct
Outline the path of PGC migration
Wall of yolk sac -> dorsal mesentary -> gonadal ridge (by week 6-7)
in males, our primary generation of cords are called what? In females these primary generation cords dissove and form a secondary generation of cords called?
medullary cords; cortical cords
the upper portion of the vagina is derived from ____, the lower portion of the vagina is derived from ___
uterine canal (mesoderm); urogenital sinus (endoderm)
What do the paramesonephric ducts give rise to?
The uterine tube and uterine canal (corpus of uterus/corpus uteri, cervix, and upper portion of vagina)
the fused caudal ends of the paramesonephric ducts contact the posterior wall of the urogenital sinus, where there is a thickening of the sinus called ___?
sinus tubercle
Two solid evaginations grow out from the sinus and these are called what?
sinovaginal bulbs
When the sinovaginal bulbs proliferate they form what?
vaginal plate
What are the wing-like expansions of the vagina that form around the caudal end of the uterus?
Vaginal fornices
What is the thin tissue plate that separates the lumen of the vagina from the urogenital sinus?
hymen
what structure contains the ovarian vasculature?
the suspensory ligament of the ovary
The ovaries have a cranial and caudal genital ligament; what do each of these ligaments form in the female adult reproductive system?
cranial genital ligament forms suspensory ligament of the ovary; caudal genital ligament forms ligament of the ovary proper and the round ligament of the uterus
which structure in females can also be recognized as the gubernaculum?
the caudal genital ligament
In the female, which are homologous structures to the scrotum in the males?
Labia majora
what causes the formation of cloacal folds
the migration of mesenchymal cells from the primitive streak to the cloacal membrane
cranial to the cloacal membrane, the folds unite to form the ___?
genital tubercle
Caudally to the genital tubercal, the folds are subdivided into ___ & ___?
urethral folds; anal folds
On each side of the urethral folds, ____ is formed which leads to ___ in males & ____ in females
genital swellings; scrotal swelling; labia majora
the development of external genitalia in males is characterized by what?
The rapid elongation of the genital tubercle now called the phallus
The two urethral folds close over the urethral plate forming what? And at what month is this completed?
penile urethra; 3rd month
How is the external urethral meatus formed?
ectodermal cells from the tip of the glans penetrate inwards forming the short epithelial cord which later obtains a lumen
the line of fusion of the scrotal swelling is called what?
scrotal septum
In females, the urethral folds do not fuse, developing into what?
labia minora
