Development Flashcards
When is genetic/chromosomal sex determined?
At fertilization
When is gonadal sex determined?
6 weeks
When does the differentiation of the reproductive system begin?
6 weeks
When can phenotypic sex be determined?
8 weeks
What are the hormones involved in male reproductive system differentiation?
SRY, SOX9, testosterone
What are the hormones involved in female reproductive system development?
RSPO1, WNT4, estrogen
What does the undifferentiated gonad give rise to?
Both the testes and the ovaries
What does the gonad originate from?
The genital ridge
What is the genital ridge?
It is a thickening of intermediate mesoderm covered by coelomic epithelium
What is the role of the primordial germ cells in the reproductive system?
They emigrate to the gonads and primitive sex chords
What happens if the primordial germ cells fail to reach the genital ridge?
The gonads do not development
What is responsible for ovarian development?
The DAX-1 gene on the short arm of the X chromosome
Which cell in the biopotential gonad is responsible for producing testosterone?
Leydig cells
What cell in the biopotential gonad is responsible for producing oestrogen?
Granulosa/follicular cells
What is essential for male development?
The Y chromosome and the presence of SRY
Describe the relationship between the mesonephric and paramesonephric ducts
They are a competing system where one must be eliminated for the other to differentiate
How does testosterone act on the reproductive system?
It acts directly on the mesonephric duct to drive differentiation into male genital ducts
What are the effects of fetal testosterone?
- Retention of a subset of mesonephric tubules as efferent ductules of the rete testis
- Persistence of the mesonephric duct and differentiation into epididymis, vas deferens, seminal vesicle and ejaculatory duct
What causes degeneration of the paramesonephric ducts?
Antimüllerian hormone (AMH)
What is the remnant of the uterus in males?
The Utriculus prostaticus
What are the remnants of the degenerated paramesonephric ducts in males?
The appendix epididymis and the appendix testis
What does the craneal portion of the paramesonephric duct differentiate into?
The uterine tubes
What does the caudal portion of the paramesonephric duct differentiate into?
They fuse to from the uterus
What must be removed during the forming of the uterus?
The uterine septum
What is responsible for the development of the external male genitalia?
Dihydrotestosterone (DHT)
What is the function of dihydrotestosterone?
It stimulates development of the external male genitalia
What cause the differentiation of the external female genitalia?
The absence of DHT
What are the phases of testicular descent?
- Transabdominal phase
2. Transinguinal phase
Describe Cryptorchidism
Undescended testes
Describe ectopic testes
Testes that are in an abnormal location
What is Swyer Syndrome?
The presence of XY chromosomes in females
What is Turner syndrome?
The absence of one X chromosome (X,0) in females
What is a possible cause of Swyer syndrome?
Mutation on SRY gene
