L11 - Life of a Sperm COPY Flashcards
THE TESTIS
i) what is the outermost layer called that is continous with the peritoneum?
ii) what is the thick fibrous capsule that divides the testes into lobules called?
iii) where does the first stage in spermatogenesis occur? where does the spermatozoa then pass to? (4)
iv) label diagram
i) tunica vaginalis
ii) tunica albuginea
iii) in the seminiferous tubules
- then rete testes > epididymis > ductus epidid > vas deferens
iv) A = spermatic cord, B = vaginalis, C = albuginea,
D = seminiferous tubule, E = rete testes
FUNCTION AND COMPARTS OF THE TESTES
i) what are the two main products from the testes?
ii) what happens in the seminiferous tubules?
iii) which cells are found adjacent to the tubules? what hormone do they produce under the influence of LH?
iv) which hormone is synthesised from acetate and cholesterol?
i) spermatozoa and hormones
ii) sperm is produced
iii) leydig cells are found adjacent to SNT and produce testosterone under LH influence
iv) testos is synth from acetate and cholesterol
HORMONES FROM TESTIS
i) what are the most important hormones produced by testis?
ii) how much testosterone is secereted daily?
iii) name two places its secreted into
iv) what is testosterone converted to in the seminiferous tubule? under the action of which enzyme? which cell does this happen in?
v) why does testosterone pass into the SNT?
i) androgens
ii) 4-10mg
iii) mostly blood but some lymph
iv) in SNT testos > DHT by 5a reductase
- happens in sertoli cells
v) testosterone passes to SNT as its required for spermatogenesis
PITUITARY CONTROL
i) what happens to androgen levels at puberty? what does this allow to happen?
ii) what may be seen in the testes after removal of of the pit gland? what happens to sperm production?
iii) which pituitary hormone stimulates leydig cells to produce androgens?
iv) which pituitary hormone stimulates sertoli cells to do spermatogenesis?
i) androgen levels increase at puberty and this allows spermatogenesis to commence
ii) testes will shrink and spermatogen will arrest
iii) LH stim leydig cells to prod androgens
iv) FSH stimulates sertoli cells to make sperm
SEMINIFEROUS TUBULES
i) approx how long are they?
ii) which cells surround them?
iii) which two cell types are found within the tubules?
iv) which two types of junctions between sertioli cells creates physiological compartments?
v) which two compartments are formed?
i) 30-80cm
ii) surrounded by myoid cells then a basement membrane
iii) sertoli cells and spermatogenic cells
iv) tight and gap juncs between sertoli cells
v) basal compart and adluminal compart
SPERMATOGENESIS STAGES
i) what are the three stages?
ii) how many spermatozoa are produced per gram of testis per second?
i) 1) mitotic proliferation to produce lots of cells
2) meiotic division to gen genetic diversity
3) cell modelling to pakcage chromos for delivery to oocyte
ii) 300 to 600 per sec
SPERMATOGENESIS STAGE 1 - MITOSIS
i) which cells are reactivated at puberty?
ii) which compartment of the SNT does mitosis happen?
iii) which cells emerge from this that then undergo more division into more clones?
iv) after the last division = what do the clones divide to form? where do these cells inhabit in which cell?
v) is cytoplasmic division complete at this point?
i) germ cells of immature testis (prospermatogonia)
ii) basal compartment
iii) A spermatogonia emerge then divide more
iv) clones divide to form resting primary spermatocytes
- these inhabit cavities formed in sertoli cell cytoplasm
v) no - spermatocytes are linked by cytoplasmic bridges
SPERMATOGENESIS STAGE 2 - MEIOSIS
i) where do primary spermatocytes push through to get to which compartment?
ii) which phase do they then enter? what are they protected by?
iii) what happens to paired homologous chromos? (3) what are they sensitive to at this time?
iv) what happens to the homologous chromos at the end of the first division? where do they travel to?
v) which process happens to form short lived secondary spermatocytes? what do they quickly divide to become?
i) primary spermatos push through sertoli cell junctions to get to the adluminal compartment
ii) then enter meiotic prophase
- protected by the physiological barrier
iii) paired homo chromos undergo break and swapping segments then rejoining
- sensitive to damage at this time
iv) end of first div the homo chromos are seperated and move to opp ends of the meiotic spindle
v) cytoplasm then divides which forms secondary spermatocytes
- 2nd spermatos then quickly divide and form haploid spermatids
SPERMATOGENESIS STAGE 3 - PACKAGING
i) label 1-5
ii) what is the function of each?
1) acrosome - penetrates the oocyte
2) cap region - forms for sperm oocyte fusion
3) nucleus - packed with chromosomes
4) midpiece - contains mitochondria
5) tail - for motility and forward propulsion
THE SPERMATOGENIC CYCLE
i) how often does spermatogenesis occur?
ii) how many days is the inerval between the spermato process starting and the new stem cells at the same location starting to generate new clones?
iii) how many days does it take to complete spermatogenesis? (four stages of how many days?)
iv) what happens to allow continuous fertility?
i) continuously
ii) 16 days between new generations starting to be produced
iii) days 64 days to complete
- four rounds of 16 days
iv) small regions of the SNT are activated together and adjacent synchronised clones of spermatogenesis are seen
- the spermatogenic wave
FINAL STAGES OF MATURATION
i) where do spermatozoa travel to once made?
ii) what do they then pass to to get to the epididymis? what happens here? (2)
iii) at what point can sperm twitch and at what point can they swim
iv) what is this process dependent on?
i) sperm travel to the rete testes
ii) then pass through vasa efferntia (efferent duct) to the epididymis
- in epidid - fluid is absorbed and sperm is concentration
iii) sperm can twitch in the rete testes and can swim by cauda epididymis
iv) process is dependent on androgens
SEMEN
i) what two main things does it contain?
ii) name three glands that contribute to the secretion at the time of ejaculation
iii) what is the avg volume of ejaculate?
iv) name four cellular components of semen
v) name three roles of the fluid component
i) spermatozoa mixed with secretions
ii) prostate, bulbourethral and seminal vesicles
iii) 3ml
iv) cellular components = spermatozoa, epithelial cells, spermatogenic cells and leucocytes
v) nutrition (fructose/sorbitol), buffer (protects against vaginal acidity), antioxidants
ENDOCERVIX/CERVICAL MUCUS
i) what does it secrete?
ii) what does it contain a network of? what is the role of this?
iii) which hormone stimulaes watery mucus
iv) which hormone inhibits secretory activity?
v) name three properties that can be used to assess cervical mucus
i) mucus
ii) network of mucin fibrils that help guide the spermatozoa
iii) oestrogen stimulates watery mucus
iv) progesterone inhibits secretions
v) consistency, elasticity/thickness, ferning (crystallisation on glass surface)
ENDOCERVIX AND SPERM
i) when is the cervix most receptive to sperm?
ii) what does it protect the sperm from?
iii) which two things may it select sperm on?
iv) which next stage of sperm maturation does it initiate?
i) most receptive at ovulation
ii) protects sperm form hostile vagina
iii) selects sperm motility and morphology
iv) initiates capacitation
SPERM CAPACITATION
i) what is it?
ii) what does it cause?
iii) what does it allow
i) stripping of glycoprotein from the surface of the sperm which accumulates in the epididymis
ii) causes hyperactive motlilty
iii) makes sperm responsive to signals from the oocyte
