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
What is a secondary male infertility?
- Failure of pituitary OR hypothalamus
What will plasma tests show for a secondary male infertility?
- LOW gonadotrophins (lH and FSH) and LOW testosterone
What is the role of the female reproductive system?
- To produce eggs and nurture and develop fetus
What do we mean when we say that female fertility is epsodic?
- Female is NOT CONSTANTLY FERTILE (only fertile once a month after oocyte has been released)–> pattern of release of oestrogen and progesterone
What are the two functions of the ovaries?
- To produce OVA (oogenesis)
2. To secrete female sex hormones–> estrogen and progesterone
Which hormone is the period BEFORE ovulation dominated by?
- Estrogen
Which hormone is the period AFTER ovulation dominated by?
- Progesterone
Is the female reproductive system continuous like the male reproductive system?
- NO
- contains a gap between the ovary and fallopian tube –> some oocytes can’t make it and are lost in peritoneal cavity–> ECTOPIC pregnancy (can befetilised and implanted outside of tube)
Where is the ovary located?
- In the pelvic region of the body inferior to the fallopian tubes and attached to the uterus via broad ligament
- Has a number of follicles in stroma of connective tissue (cortex of ovary)
What is a primary follicle?
- Has primary oocyte surrounded by SINGLE layer of connective tissue derived granulosa cells
What happens to oocytes NOT surrounded by granulosa cells?
- They die by apoptosis
what is oogenesis?
- Development of primordial germ cells to mature fertilisable oocytes
Oocytes are in a state of ________ and are reinitiated at ovulation and fininshed at fertilisation
-: Suspended meiotic division
What occurs in the process from primordial follcile –> Primary follicle?
- Oocyte grows in size
- More granulosa cells (but still only single layer)
- Zona pellucida forms
What occurs in the process from primary follicle –> Preantral follicle?
- Many more granulosa cells form
- Theca cell forms on outside (developed from connective tissue)
What occurs in the process from Primary (preantral) follicle–> Early antral Follicle?
- Antrum forms –> contains secretory fluid of granulosa cells
- theca cell INCREASES to MULTIPLE layers
What occurs in the process from Early Antral Follicle–> Graafian (mature) follicle?
- ALL cell layers increase (more granulosa and theca cells)
- Antrum layer
- Oocyte moves to ONE POLE of follicle
Where (in general) do FSH and LH stimulate steoid synthesis in ?
- In Antral follicles
In female reproduction, which cell type does FSH stimulate?
- Granuloa cells
In female reproduciton, which cell type does LH stimulate?
- Theca cells
What do Theca cells produce (female reproduction) ?
- Androgens (Androstenedione–> testosterone)
- they are a substrate for estrogen production
What is the actions of the estrogens (oesdradiol) produced by the granulosa cell?
- Further increase granulosa cell proliferation (positive feedback)