Reproduction Flashcards
What does the X chromosome encode for?
Androgen receptor
Female internal genitalia develop from the ___ of the gonadal ridge.
Cortex
Male internal genitalia develop from the ___ of the gonadal ridge.
Medulla
What are the two types of cells in the ovary and what do they do?
- Granulosa cells: secrete and synthesize androgen, progesterone, and inhibin
- Thecal cells: secrete androgens and progesterone
What receptors are found on granulosa cells?
LH and FSH
What receptors are found on thecal cells?
LH
What are the two types of cells in the testes and what do they do?
- Sertoli cells: make AMH and inhibin B
2. Leydig cells: make androgens
What stimulates formation of the internal genitalia from the Wolffian duct? What happens without it?
Testosterone and DHT; the Wolffian duct regresses
What does the genital tubercle become in males and females?
Males: glans penis
Females: clitoris
What do the urogenital folds become in males and females?
Males: ventral penis
Females: labia minora
What does the urogenital sinus become in males and females?
Males: prostate
Females: lower vagina
What do the labioscrotal folds become in males and females?
Males: scrotum
Females: labia majora
When does female oogenesis arrest?
First: meiosis I arrests in the diplotene stage of prophase until activation at puberty
Second: meiosis II at metaphase II until fertilized by pserm
What causes the first arrest of female oogenesis?
Oocyte maturation inhibitor (OMI)
When does male spermatogenesis arrest?
Mitosis until puberty
What causes an XX genotype, male phenotype?
Presence of SRY gene
What causes an XY genotype, female phenotype?
Mutation of SRY gene
What causes an XO genotype, female phenotype?
Turner’s syndrome
What are the symptoms of Turner syndrome?
Gonadal dysgenesis (no ovaries, streak of fibrous tissue instead), short stature, shield chest, webbed neck, upper torso deformities, no puberty, no menstrual cycles
What causes an XXY genotype, male phenotype?
Klinefelter syndrome (meiotic nondisjunction)
What are the symptoms of Klinefelter syndrome?
Small, hyalinated testes, infertile, low testosterone, micropenis, eunuchoid body (lower segment > upper segment), short arms, gynecomastia
What is the genotype and phenotype in male pseudohermaphroditism?
XY, testes present with some/all female internal/external genitalia present
What are two causes of male pseudohermaphroditism?
Complete and partial androgen resistance (loss or mutation of X-linked androgen receptor gene)
What are the hormone levels in complete and partial androgen resistance?
Complete: high androgens, high LH, high to normal FSH
Partial: high androgens, high to normal LH, normal FSH
What is the phenotype in complete androgen resistance?
Female with blind vaginal pouch, no ducts, undescended testes, lack of androgen effects, high estrogen induces partial development of female characteristics
What is the phenotype in partial androgen resistance?
Ambiguous with blind vaginal pouch, only Wolffian ducts, undescended testes, gynecomastia
What is the genotype and phenotype in female pseudohermaphroditism?
XX, ovaries present with some/all male internal/external genitalia also present
What causes female pseudohermaphroditism?
Developmental defects such as fetal congenital adrenal hyperplasia (most common) and maternal androgen excess
What is the phenotype of female pseudohermaphroditism?
Virilization due to increased androgens, ambiguous genitalia, advanced skeletal age
Describe true hermaphroditism.
Testes and ovaries present, ambiguous genitalia, cryptorchidism, hypospadias, may be caused by possible SRY translocation or loss of RSPO1 gene, no spermatogenesis
LH stimulates ___ and FSH stimulates ___.
Steroidogenesis; gametogenesis
What cells form the blood-testes barrier?
Sertoli cells
What converts DHEA to androstendione?
3-beta-HSD
What converts androstendione to testosterone?
17-beta-HSD
What converts testosterone to estradiol?
Aromatase
What converts testosterone to DHT?
5-alpha-reductase
Which has a higher binding affinity for androgen receptor, testosterone or DHT?
DHT
Describe the production of semen.
Sperm is produced in the seminiferous tubule. It matures in the epididymis and travels through the vas deferens. At the ampulla, seminal vesicle secretions are added. This travels through the ejaculatory ducts where prostate fluid is added. Bulbourethral fluid is added prior to entering the urethra.
What is secreted by the seminal vesicles?
Nutrients (fructose, citric acid, etc.), prostaglandins, alkaline substances
What is secreted by the prostate gland?
Alkaline secretions, proteolytic enzymes
What is secreted by the blubourethral gland?
Mucous (upon arousal)
What is the first fluid to be expelled in ejaculate?
Secretions from the prostate gland
What are the 4 phases of testicular descent?
- Embryonic position
- Transabdominal phase
- Inguinoscrotal phase
- Elongation of cord
Describe the development of sperm.
- Stem cells lie along the basement membrane of seminiferous tubules.
- Spermatagonia under continuous mitotic division; a minority commit to further differentiation which undergo meisosis and mature into spermatozoa.
- Primary spermatocytes divide, producing 2 daughter cells (secondary spermatocytes) with 23 chromosome pairs.
- 2 Secondary spermatocytes divide again, producing 4 spermatids with 23 single chromosomes.
- The 4 spermatids become 4 functional spermatozoids.
Describe the interaction between Leydig and Sertoli cells.
Leydig cells produce testosterone, which acts on nearby Sertoli cells to increase local testosterone levels. Sertoli cells can convert some to estradiol, which is used by the Leydig cells to promote steroidogenesis.
What occurs in spermatogenesis?
Spermatogonia –> 4 haploid spermatids
What occurs in spermiogenesis?
Spermatids –> spermatozoa
What occurs in spermiation?
Release of spermatozoa from Sertoli cells into the lumen
When is maturation of sperm completed?
Upon entering the vagina (capacitation)