Sperm - Origins and Role Flashcards
What is the acrosome and what is its function
Cap on head of sperm that contains enzymes to allow it to digest its way into the oocyte
In which structure are spermatozoa made?
Seminiferous tubules
In which structure do spermatozoa mature?
Epididymis
What cells line seminiferous tubules and what is their function?
Sertoli cells - support and nourish spermatozoa
What is the female equivalent of Sertoli cells?
Granulosa cells
Where cells are found on the outside of seminiferous tubules?
Leydig cells
What is the function of Myoid cells?
Maintain blood-testis barrier and prevent antibodies recognising sperm
Rising levels of what during puberty re-starts mitosis of prospermatogonia?
Androgens driven by release of GnRH
What do spermatogonial stem cells initially differentiate into?
Spermatogonium type A1
how many type A1 spermatogonium clones can one spermatogonial stem cell produce?
16
How many mitotic cell divisions does type A1 spermatogonia undergo to form a resting primary spermatocyte
5 synchronised: Type A1 > A2 > A3 > A4 >intermediate spermatogonium > type B. Followed by a final mitosis to form
resting primary spermatocytes.
What is formed at the end of meiosis 1?
Secondary spermatocytes
What is formed at the end of meiosis 2?
early spermatids
How many spermatids are formed from one type B spermatogonium?
4
What links the spermatids together and what is the purpose of it?
Cytoplasmic bridges - gives it a degree of synchronicity
What process occurs to make sure clones are not all the same so there is individuality?
Meiotic chiasmata
What is the name of the process where spermatids look more like a characteristic sperm and acquire morphology to enable them to fertilise an egg?
Spermiogenesis
What secretes the acrosomal vesicle?
Golgi apparatus which has moved to proximal end of spermatid
What is the final product of spermiogenesis?
Spermatozoa
In the seminiferous tubueles what is occuring to make sure there are always developed sperm readily available?
Spermatogenic wave
What are the 3 functions of the epididymis?
1) sperm concentration
2) sperm maturation
3) sperm storage
What cells do LH stimulate in males and what do these cells produce?
Stimulate Leydig cells to produce testosterone
What are Leydig cells analogous to in females?
Theca cells
Does testosterone have negative or positive feedback on the hypothalamus?
Negative - less LH produced
What cells do FSH bind to and what is the result of this?
Bind to Sertoli cells which stimulates the production of androgen receptors - needed for sperm development
In males what are androgens converted to
5 alpha-dihydrotestosterone (a more potent form of testosterone)
What percentage volume to seminal vesicles contribute to semen volume?
60%
What nutrients does seminal fluid contain?
Fructose
Ascorbic acid (vit C - good antioxidant)
Prostaglandins
pH <7
What percentage volume does the prostate contribute to semen?
20-30%
What do Cowper’s/bulbourethral glands produce? and what volume of semen do they make up
Mucous to lubricate action of coitus - 5%
What is the general aim of prostate drugs? (treatment of benign prostate hyperplasia/cancer)
To interrupt with androgen signalling as this is what the prostate needs to work
Name a GnRH antagonist
Goserelin
Name an androgen receptor antagonist
Bicalutamide
Name a reductase inhibitor used to treat BPH/prostate cancer
Finasteride
What is classed as a ‘normal’ sperm production?
> 15 million sperm per ml
40% motility
32% should have progressive motility
4% need to have normal morphology
What is the term used to mean low sperm count?
Oligozoospermia
What is aspermia?
complete absence of semen caused by retrograde ejaculation back into bladder
What is azoospermia
complete absence of sperm - dysfunction of HPG axis, genetic conditions, chemotherapy
What term is given to sperm with low motility?
Asthenozoospermia
What name is given to sperm with abnormal morphology
Teratospermia
name the physiological process of desire/arousal
Excitement > plateau > Orgasm/climax > resolution - males require an absolute refractory period
What substance acts as a vasodilator of blood vessels of corpora cavernosa during erection?
Nitric oxide
Other than NO what else vasodilates blood vessels to create an erection?
cyclic GMP
What is detumescence?
end of stimulation - get muscles relaxing and end of erection
What enzyme is responsible for breaking down cyclic GMP at the end of sensory stimulation?
Phosphodiesterase V (PDE5)
Name the mechanism of action and use of Sildenafil
PDE5 inhibitor used to treat erectile dysfunction
