Development of Reproductive System Flashcards
What are primordial germ cells?
Progenitor cells of oogonia or spermatogonia
Where do the primordial germ cells begin?
Yolk sac wall
In what week do the primordial germ cells begin to migrate?
Week 5
In week 5, what do the primordial germ cells migrate up?
Up the dorsal mesentary
In week 5, where do the primordial germ cells migrate to?
To the genital ridge
Once the primordial germ cells have entered the genital ridge, they stimulate production of?
Somatic support cells
In males, what will the somatic support cells become?
Sertoli cells
In females, what will the somatic support cells become?
Follicle cells
In what week do the primordial germ cells stimulate the development of the somatic support cells?
Week 6
2 sets of reproductive ducts form from?
Within the intermediate mesoderm of the urogenital ridge
What are the 2 reproductive ducts?
Mesonephric duct
Paramesonephric duct
The Mesonephric duct will eventually give rise to?
Epididymis
Vas deferens
Seminal vesicle
Ejaculatory duct
The Paramesonephric duct will eventually give rise to?
Oviduct
Uterus
Upper vagina
What gene on what chromosome determines gonad type?
SRY gene on the Y chromosome
What determines the duct and genitalia development?
Gonad type
In the absence of the SRY gene, the development is?
Female
Between what days is the SRY gene on the Y chromosome active?
Day 41-52
In what cells is the SRY gene expressed?
Somatic support cells (sertoli)
Somatic support cells (sertoli) surround the primordial germ cells to organize?
Seminiferous tubules
In the seminiferous tubules, there are cells that differentiate into?
Fetal Leydig cells
For testis development, in the somatic support (sertoli) cells, SRY expression causes what cascade of events?
- Activation of Sox9
- Which stimulates release of AMH
- AMH controls regression of the paramesonephric duct
SRY gene activates Sox9. What is the hormone regulated by Sox9?
AMH - Anti-Mullerian Hormone
What does AMH do and when?
Controls regression of the paramesonephric duct between weeks 8-10
For testis development, what are the remnants of the paramesonephric duct?
Appendix testis
Prostatic utricle
Sertoli cells produce what 2 things?
AMH
Androgen binding factor
Androgen binding factor causes what at puberty?
Spermatogonia –> Spermatozoa
What are the 2 types of leydig cells?
Fetal leydig cells
Adult leydig cells
What 2 things do Fetal leydig cells produce?
Testosterone
5alpha-reductase
Fetal leydig cell testosterone controls?
Mesonephric duct differentiating into the epididymis, vas deferens, seminal vesicle, and ejaculatory duct
Fetal leydig cell 5alpha-reductase controls what reaction?
Fetal leydig testosterone –> Dihydrotestosterone
Fetal leydig Dihydrotestosterone stimulates formation of?
External genitalia:
- Scrotum
- Penis
- Prostate
Adult leydig cells stimulate what at puberty?
Spermatogenesis
Male sexual behavior
Masculinization of the brain
Seminal vesicle forms from?
Buds from Mesonephric duct (intermediate mesoderm of urogenital ridge)
Prostate gland forms from and at what week?
Buds from endoderm of urogenital sinus at week 10
Bulbourethral glands form from?
Endodermal buds
List the things that are formed with external genitalia during the INDIFFERENT stage
Urogenital plate Glans plate Genital tubercle Urogenital folds Labioscrotal folds Urogenital groove
Rupture of the cloacal membrane opens the phallic portion of the urogenital sinus to the exterior and forms?
Endodermally derived urogenital plate
What is the glans plate and where is it located?
The glans plate is remnants of the cloacal membrane and sits ventrally to the urogenital plate
What is the genital tubercle made of?
Swelling of mesoderm covered with ectoderm
Where is the genital tubercle?
Ventral and cranial to the urogenital plate
What and where are urogenital folds?
Swellings that form on both sides of the urogenital plate
What and where are the labioscrotal swellings?
Swellings that form on both sides of the urogenital folds
Where does the urogenital groove form?
On the ventral surface of the urogenital plate
What drives the external genitalia development in males?
Dihydrotestosterone (DHT) - from Fetal leydig cells
What does DHT drive in the formation of the external male genitalia?
- Growth and elongation of the genital tubercle and the urogenital plate AND
- Fusion of the labioscrotal swellings to form the scrotum
How is the male urethra formed and during what week?
Urogenital folds grow toward each other and fuse during week 14
The urogenital groove becomes _____ in the male
Urethra
Urogenital folds do NOT fuse properly in male genitalia
Hypospadias
Improper ventral body closure of male genitalia
Epispadias
What gene is absent in females?
SRY gene
What genes are expressed in females?
WNT-4 and FOX2L
FOX2L continually suppresses?
Sox9 to maintain female gonads
Primordial germ cells of females become?
Oogonia
Oogonia then become?
Oocytes
Follicle cells surround the oocytes and block them from undergoing?
Meiosis-1
Is there a mesonephric duct in females?
No
At what weeks does uterine formation take place?
Week 9-10
The uterus is formed by?
The fusion of the inferior paramesonephric ducts
The uterine tubes are formed by?
The superior paramesonephric ducts NOT fusing
When the paramesonephric duct comes into contact with the urogenital sinus, what happens?
Stimulates proliferation of sinuvaginal bulb
Sinuvaginal bulb is made of?
Endoderm
How is the vagina formed?
The sinuvaginal bulb lengthens and then canalizes
Almost entire vagina is made of?
Endoderm
Uterus is made of?
Mesoderm (from paramesonephric ducts)
Double uterus
Didelphys
Didelphys
Double uterus from the improper/failed fusion of the paramesonephric ducts
What is vaginal agenesis normally due to?
Improper lengthening/canalization of the sinuvaginal bulb
After indifferent development of the gonads, for a female what will the urogenital folds become?
Labia minora
After indifferent development of the gonads, for the female what will the labioscrotal swellings become?
Labia majora
_____ and ______ separates urethra and vaginal opening
Growth and expansion
Describe the formation of the broad ligament
- Midline fusion of the paramesonephric ducts brings the lower urogenital ridge within the pelvic cavity and it is covered with peritoneum
- After uterus formation, the remaining tissue thins
- Tissue forms a double fold of peritoneum supporting the uterus and ovary
Round ligament of ovary is made from?
Superior gubernaculum
The round ligament of the ovary connects?
Ovary to uterus
Round ligament of uterus is made from?
Inferior gubernaculum
The round ligament of the uterus connects?
Uterus to labia majora
Disorders of Sex Development (DSD)
Congenital conditions where development of chromosomal, gonadal and anatomical sex is Atypical
Has testis but phenotype is female
Male DSD
Male DSD can be caused from?
Inadequate testosterone
5alpha-reductase deficiency
Mutations in AMH
Androgen insensitivity syndrome
Androgen insensitivity syndrome
Loss of functional androgen receptors
- Have testis but not spermatogenesis
- Have AMH so no paramesonephric system
What happens at puberty with androgen insensitivity syndrome?
Testosterone gets converted to estradiol and they exhibit female characteristics, though they do not have a period (amenorrhea)
Where are the testes usually located with androgen insensitivity syndrome?
In inguinal or labial regions
5alpha-reductase deficiency
Underdeveloped male external genitalia due to little dihydrotestosterone
What normally causes Female DSDs?
Congenital adrenal hyperplasia
What are the symptoms with female DSDs?
Masculinization of the female external genitalia
- may have fusion of the labia that is similar to a scrotum