21 - Sperm in the Female Tract

Question 1

Slide 5

Answer 1

look

Question 2

Role of vagina wrt sperm

Answer 2

• retrograde loss of sperm
• phagocytosis
• entrance into cervix

Question 3

Role of cervix wrt sperm

Answer 3

• “privileged pathways” of sperm movement
• removal of non-motile and abnormal sperm

Question 4

Role of uterus wrt sperm

Answer 4

• capacitation initiated
• phagocytosis

Question 5

Role of oviduct wrt sperm

Answer 5

• capacitation completed
• phagocytosis

Question 6

Steps in fertilization

Answer 6

1. Acrosome reaction
2. Sperm binds and penetrates oocyte
3. Male and female pronuclei develop
4. Zygote formed

Question 7

Estrogenic effect on hypothalamus? Brain?

Answer 7

Hypo/pit: increase GnRH = LH surge

Brain: mating behaviour (lordosis), phonation (vocalization)

Question 8

Estrogenic effects on reproductive tract

Answer 8

Increased:
- blood flow
- leukocytes
- mucosal secretion (lubricate, pheromones)
- growth uterine glands
- smooth muscle tone (contract to help sperm move to fert site)
- genital swelling

Question 9

Role of leukocytes in fem repro tract? When does it occur

Answer 9

• prevent infection
• protect against foreign materials

Within 6-12h after intro of sperm into uterus

Question 10

Control vs phenylephrine/ergonovine effects on sperm transport

Answer 10

Control: saline injection, 90,000 sperm AI, fertilization = 16%

Phenylephrine injection causes muscle contraction led to an increase in fertilization rate (52%)
Ergonovine = 63% fertilization rate
90,000 sperm AI

Question 11

Two types of cervical mucus forms/functions

Answer 11

1. Sialomucin: low viscosity mucus found within cervical crypts (folds). Sperm are able to move through it towards the uterus
2. Sulfomucin: high viscosity mucus found at the ends of the cervical folds. Sperm that remain in cervical lumen are stuck to sulfomucin and do not enter uterus

Slide 11

Question 12

What types of sperm move through the cervix

Answer 12

Viable sperm (ie motile & morphologically normal) are better able to gain access to this “privileged pathway”

Question 13

Slide 12

Answer 13

Characteristics of copulation in diff species**

Question 14

Two types of AI in cattle? Effectiveness?

Answer 14

Insert as soon as gun passes cervix (into uterine body) or go into uterine horn (using ultrasound scanner)

Uterine body deposition is just as efficient as cornual. Cervical deposition not effective (sperm is expelled)

Slide 13, 14

Question 15

How does AI work in pigs

Answer 15

Semen deposition into cervix
AI gun/syringe needs to have a tip that can enter cervix (spiral tip)

Needs to be fresh semen (not frozen) and a high volume to achieve fertilizations (far distance to oocytes, multiple oocytes)

Slide 15

Question 16

How does AI work in horses

Answer 16

Finger to help insert AI gun
Cervix can be tricky, unexperienced technician can cause damage

Slide 16

Question 17

How does AI work in dogs

Answer 17

Repro tract goes upwards towards dorsal part of body
Use fingers to accommodate AI gun/access vagina

With AI, low volume of semen doses deposited, much will be lost due to gravity or lost to leukocytes
Try to go as close to or past the cervix if possible

Slide 18

Question 18

Slide 18

Answer 18

Ai in sheep

Question 19

What is sperm capacitation

Answer 19

The process whereby sperm acquire fertility through interactions w the female repro tract

Ejaculated sperm not yet able to fertilize oocyte. Gain full ability once exposed to appropriate factors

Question 20

Sperm decapacitation / capacitation steps

Answer 20

In epididymus, egg-binding proteins added to sperm head membrane
Heads of ejaculated sperm then coated with de-capacitation factor that masks EBP

Capacitation factors produced by fem repro tract remove decapacitation factors
Exposed EBP interact w oocyte to initiate fertilization (acrosome reaction)

Question 21

Events leading to fertilization ** (sperm in oviduct)

Answer 21

1. Hyperactive motility (change from linear to rapid “figure-8” like movement
2. Binding to zona pellucida
3. Acrosome reaction

(only capacitated sperm do this)

Question 22

Three glycoproteins of the zona pellucida

Answer 22

ZP1 (structural)
ZP2 (structural)
ZP3 (binds to proteins on sperm membrane)

Question 23

2 zona binding sites on sperm’s oocyte binding proteins

Answer 23

1. Primary zona binding region (ZBR)
2. Acrosome reaction promoting region (ARPR)

Question 24

Slides 23, 25

Answer 24

Zona pellucida binding, acrosomal reaction**

Question 25

What is the acrosome?

Answer 25

Membrane-bound lysosome containing hydrolytic enzymes required for penetration of the oocyte zona pellucida at fertilization
Acrosomal enzymes: acrosin, zona lysin, esterases

Question 26

What is the acrosome reaction

Answer 26

Plasma membrane overlying the acrosome fuses with the outer acrosomal membrane
Fusion of the 2 membranes leads to vesiculation that allows for the release of the acrosomal enzymes

Question 27

Steps 1 and 2 in sperm-oocyte interaction (fertilization)

Answer 27

1: acrosome-reacted sperm penetrates the zona pellucida

2:
- sperm enter the perivitelline space & bind to the vitelline membrane
- zona pellucida undergoes biochemical changes to prevent other sperm from penetrating (ZONA BLOCK)

Question 28

Steps 3 and 4 in sperm-oocyte interaction (fertilization)

Answer 28

3:
- sperm is engulfed by oocyte cytoplasm and passes through the vitelline membrane
- additional alteration in oocyte membranes (vitelline block) is evoked to prevent other sperm from entering

4:
- cytoplasm shrinks
- second polar body pushed into perivitelline space
- DNA decondenses to form the male and female pronuclei

Question 29

Steps 5 and 6 in fertilization

Answer 29

5: syngamy occurs (male and female pronuclei merge)

6: single diploid (2N) nucleus forms and fertilization is complete to give a zygote

Question 30

Slides 26, 29, 31, 32

Answer 30

Oocyte, embryo