201-205. Week 6 PBL - IUI and IVF

Question 1

What type of epithelium lines the epididymis?

Answer 1

Psuedostratified columnar with stereocilia

Question 2

What is the muscular composition of the vas deferens?

Answer 2

Inner and outer longitudinal layers with middle circular layer

Question 3

What epithelium lines the vas deferens?

Answer 3

Pseudostratified columnar

Question 4

What is the role of the seminal vesicles?

Answer 4

Secretes 85% of seminal fluid volume
Secretes alkaline viscous fluid, high levels of fructose, and produces prostaglandins (aids sperm mobility and stimulates uterine contractions)

Question 5

What two cell types are contained within seminiferous tubules?

Answer 5

Sertolli cells

Spermatogenic cells

Question 6

What are the main roles of Sertoli cells?

Answer 6

Forms blood-testis barrier
To produce androgen binding protein to be released into the lumen
Provides nutrients and phagocytoses excess cytoplasm of spermatids

Question 7

What is the role of myoid cells and where are they located?

Answer 7

Around the seminiferous tubules

Produce peristalsic contractions in tubules

Question 8

What is the role of leydig cells and where are they located?

Answer 8

Located in interstitial tissue (lies between seminiferous tubules)
Produces testosterone

Question 9

What causes the production of androgen-binding protein by Sertoli cells?

Answer 9

FSH

Question 10

What are the 3 types of spermatogonia and what are their functions?

Answer 10

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

Question 11

How long does spermatogenesis take?

Answer 11

64 days approx

Question 12

At what stage does a primary spermatocyte undergo the 1st meiotic division?

Answer 12

Diplotene spermatocyte (into secondary spermatocyte)

Question 13

What is formed after the 2nd meiotic division?

Answer 13

Secondary spermatocytes divide into round spermatids which are haploid

Question 14

At what does the resting primary spermatocyte become before it moves off the basement membrane?

Answer 14

Leptotene spermatocyte

Question 15

During spermiogenesis, what happens to the following?

a) Golgi apparatus
b) Centrioles
c) Mitochondria
d) Cytoplasm

Answer 15

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

Question 16

What is the functional significance of the following structures of the spermatozoa?

a) Head
b) Midpiece
c) Tail

Answer 16

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

Question 17

FSH stimulates the Sertoli cells to do what?

Answer 17

Promote spermatogenesis and spermiogenesis
Secrete androgen-binding protein
Secrete inhibin in response to factors released by developing spermatozoa

Question 18

What stimulates testosterone production via the Leydig cells?

Answer 18

LH

Question 19

What is the function of the prostate gland?

Answer 19

Produces slightly acidic secretions
Citrate - for ATP production
Acid phosphatase and proteolytic enzymes - liquefy coagulated semen
Antibiotic properties to reduce UTIs

Question 20

What is the function of the bulbourethral gland?

Answer 20

Secretes thick mucus - lubricates glans of penis

Question 21

Define fertilisation

Answer 21

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

Question 22

How long is a sperm cell fertile for?

Answer 22

48 hours

Question 23

How long is an egg fertile for?

Answer 23

12-24 hours

Question 24

What is capacitation?

Answer 24

When sperm cells gain increasing motility and gain the ability to penetrate the egg (within the female reproductive tract)

Question 25

In what ways does the reproductive tract aid sperm motility?

Answer 25

Thin cervical mucus
Contraction of uterine muscles
Ciliary currents in fallopian tube

Question 26

What phase is the secondary oocyte in before it is fertilised?

Answer 26

Metaphase of meiosis II

Question 27

What enzyme is contained in the acrosomal cap which aids the digestion of the corona radiata?

Answer 27

Hyaluronidase (dozens of sperm must release hyaluronidase before one sperm can reach the oocyte membrane)

Question 28

What must the sperm do in order to fuse with the oocyte?

Answer 28

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

Question 29

What enzymes are required to digest through the zona pellucida?

Answer 29

Hyaluronidase and acrosin

Question 30

How is polyspermy prevented?

Answer 30

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