REPRODUCTION Flashcards
What is the function of the testes?
- To make sperm (mature spermatagonia) for spermatogenesis
What can cause infertility in men?
- If a varicose vein occurs
- this will INTERRUPT the blood flow so venous blood can’t cool arterial blood coming into testis
Which two components is the testis made of?
- Seminiferous tubules
- Interstitial compartment (b/w seminiferous tubules (Leydig cells –> makes testosterone) –> contains blood vessels, lymphatics, and nerves
Which two structures are the seminiferous tubules and interstitial compartment (leydig cells) REGULATED by ? -
- Pituitary and hypothalamus
What do leydig cells produce and which hormone are they regulated by?
- Produce TESTOSTERONE and are regulated by LH
so decreased LH means decreased testosterone production
Why do smeiniferous tubules have a high amount of testosterone?
- Because leydig cells are SO CLOSE to the tubules and testosterone is a steroid hormone so can easily diffuse in
In males, what hormone receptors do leydig and sertoli cells have respectivley?
- LH (leydig) and FSH (sertoli) `
What hormone do Leydig cells and Sertoli cells produce respectively?
- Testosterone (leydig) and Estrogen (MAINLY INHIBIN THOUGH) for Sertoli cells
What is the role of sertoli cells mainly? (male repro.)
- They stimulate spermatogenesis
What does the inhibin negatively feedback on when produced by the sertoli cells in males?
-Feeds back negatively on the anterior pituitary to decrease FSH production
What does Testosterone feedback on in males?
- LH
What are the androgenic actions of testosterone?
- Initiation and maintenance of spermatogenesis, maintenance of secondary sex characteristics (from testosterone–> DHT (Dihydrotestosterone)
What are the anabolic actions of testosterone?
- INCREASE in basal metaobolic rate
- INCREASE in rate of protein synthesis
- INCREASE in muscle mass
- INCREASE in RBCs (erythropoesis)
What happens after puberty has hit in males?
- testosterone STIMULATES spermatogenesis
- INCREASES growth of reproductive ducts and glands
- INCREASES the size of the penis
- ENHANCES ability to maintain en erection
- STIMULATES male secondary sex characteristics (not involved in reproduction)
Where does spermatogenesis occur?
- In the seminiferous tubules of testis
Where do sertoli cells sit and what are 5 roles of it?
- Sit in the basement membrane and cytoplasm surrounds developing germ cells
1. Produce INHIBIN which feeds back to pituitary to DECREASE FSH secretion
2. Paracrine activity within testes and acts on leydig cells
3. Produce ABP (androgen binding protein)–> to allow for androgen rich environment
4. Sertoli cells convert testosterone–> estradiol
5. Important in blood brain barrier (form tight junctions)
What are the mechanisms of development of spermatazoa into sperm? (maturation)
- Maturation occurs in epididimys
- Head of mature sperm CONDENSES –> so it only has nucleus and acrosomal cap that is formed from golgi
What do the acrosomal enzymes allow for?
- Allow sperm to access ovum once in female reproductive tract
What are the 3 components of the sperm tail ?
- Central skeleton of 11 microtubules–> axoneme similar to other cilia in other cells
- Thin membrane covering axoneme
- Collection of mictochondria SURROUNDING axoneme
How is testosterone secreted (in what form)?
- Bound to ABP (androgen binding protein)
What is released in pulses every 90 mins to stimulate release of LH and FSH?
- GnRH form hypothalamus
Which two hormones are required for spermatogenesis to occur?
- FSH and HIGH TESTOSTERONE
What are examples of primary male infertility?
- Failure WITHIN testes, seminiferous tubules, or leydig cells
e. g. Klinefelters syndrome, and chryptochidism-failure of testes to descend)
What will a plasma test show for testosterone and LH + FSH levels?
- LOW testosterone and HIGH LH and FSH