201-205. Week 6 PBL - IUI and IVF Flashcards
What type of epithelium lines the epididymis?
Psuedostratified columnar with stereocilia
What is the muscular composition of the vas deferens?
Inner and outer longitudinal layers with middle circular layer
What epithelium lines the vas deferens?
Pseudostratified columnar
What is the role of the seminal vesicles?
Secretes 85% of seminal fluid volume
Secretes alkaline viscous fluid, high levels of fructose, and produces prostaglandins (aids sperm mobility and stimulates uterine contractions)
What two cell types are contained within seminiferous tubules?
Sertolli cells
Spermatogenic cells
What are the main roles of Sertoli cells?
Forms blood-testis barrier
To produce androgen binding protein to be released into the lumen
Provides nutrients and phagocytoses excess cytoplasm of spermatids
What is the role of myoid cells and where are they located?
Around the seminiferous tubules
Produce peristalsic contractions in tubules
What is the role of leydig cells and where are they located?
Located in interstitial tissue (lies between seminiferous tubules)
Produces testosterone
What causes the production of androgen-binding protein by Sertoli cells?
FSH
What are the 3 types of spermatogonia and what are their functions?
Type A (dark) - reserve stem cells recruited in cases of severe damage to spermatogenesis Type A (pale) - renewing stem cells Type B - differentiating progenitors which form spermatocytes
How long does spermatogenesis take?
64 days approx
At what stage does a primary spermatocyte undergo the 1st meiotic division?
Diplotene spermatocyte (into secondary spermatocyte)
What is formed after the 2nd meiotic division?
Secondary spermatocytes divide into round spermatids which are haploid
At what does the resting primary spermatocyte become before it moves off the basement membrane?
Leptotene spermatocyte
During spermiogenesis, what happens to the following?
a) Golgi apparatus
b) Centrioles
c) Mitochondria
d) Cytoplasm
a) Forms the acrosomal cap
b) Forms the flagellum
c) Rearrange and gather in middle area
d) Redistributes - residual body of cytoplasm is pinched off as a cytoplasmic droplet
What is the functional significance of the following structures of the spermatozoa?
a) Head
b) Midpiece
c) Tail
a) Contains condensed and inactive DNA, surrounded by acrosome which contains enzymes required to penetrate the egg
b) Contains many mitochondria to provide energy
c) Generates movement
FSH stimulates the Sertoli cells to do what?
Promote spermatogenesis and spermiogenesis
Secrete androgen-binding protein
Secrete inhibin in response to factors released by developing spermatozoa
What stimulates testosterone production via the Leydig cells?
LH
What is the function of the prostate gland?
Produces slightly acidic secretions
Citrate - for ATP production
Acid phosphatase and proteolytic enzymes - liquefy coagulated semen
Antibiotic properties to reduce UTIs
What is the function of the bulbourethral gland?
Secretes thick mucus - lubricates glans of penis
Define fertilisation
The fusion of two haploid gametes (23 chromosomes each) to form a diploid zygote (46 chromosomes)
Due to the secondary oocyte being penetrated by a sperm cell
How long is a sperm cell fertile for?
48 hours
How long is an egg fertile for?
12-24 hours
What is capacitation?
When sperm cells gain increasing motility and gain the ability to penetrate the egg (within the female reproductive tract)
In what ways does the reproductive tract aid sperm motility?
Thin cervical mucus
Contraction of uterine muscles
Ciliary currents in fallopian tube
What phase is the secondary oocyte in before it is fertilised?
Metaphase of meiosis II
What enzyme is contained in the acrosomal cap which aids the digestion of the corona radiata?
Hyaluronidase (dozens of sperm must release hyaluronidase before one sperm can reach the oocyte membrane)
What must the sperm do in order to fuse with the oocyte?
Must have enough acrosome
Must bind to sperm receptors on zona pellucida
This then activates the release of hyaluronidase and acrosin to digest a path through the zona pellucida
What enzymes are required to digest through the zona pellucida?
Hyaluronidase and acrosin
How is polyspermy prevented?
1st sperm makes contact with oocyte, causing depolarisation of the oocyte
Na+ permeability of oocyte increases and there is sodium influx
Na+ entry causes Ca2+ release from the smooth ER
Calcium then causes the release of cortical granules which INACTIVATE sperm receptors and HARDEN the zona pellucida
