Midterm 2 - Lecture 18

Question 1

3 major structures of the sperm head

Answer 1

1. nucleus
   - oval and flattened
   - DNA is highly condensed
2. Acrosome
   - membrane-bound lysosome containing hydrolytic enzymes required for penetration of the oocyte zona pellucida at fertilization
3. Post-nuclear cap
   - lower portion of sperm head not covered by acrosome

Question 2

What is the tail axoneme responsible for?

Answer 2

• sperm motility
• outer pairs of microtubules of the 9+9+2 pattern generate the bending waves of the tail as adjacent pairs slide past one another in a coordinated movement

Question 3

Sperm metabolism

Answer 3

• sperm motility indicates its metabolic state
• energy required for motility is derived from substrates in the seminal fluid

Question 4

For how long is sperm viable in the epididymus vs ejaculation?

Answer 4

Epididymus
- no O2 or energy substrates
- sperm is viable for DAYS

Ejaculation
- O2 and energy available
- sperm is viable for HOURS

Question 5

What is sperm capacitation?

Answer 5

• the process whereby sperm acquire fertility through interactions with the female reproductive tract

Question 6

Why is sperm capacitation necessary?

Answer 6

ejaculated sperm are not yet able to fertilize an oocyte; they only become able to fertilize once they have been exposed to appropriate factors/environment experience appropriate modifications

Question 7

What events occur during sperm capacitation?

Answer 7

• in the epididymus “Egg-binding proteins” are added to the sperm head membrane that allow them to bind to an oocyte
• heads of ejaculated sperm are coated with de-capacitation factors that mask egg-binding proteins
• capacitation factors produced by the female repro tract remove decapacitation factors
• exposed egg-binding proteins able to interact with oocyte to initiate fertilization

Question 8

What is the acrosome reaction?

Answer 8

• fusion of the sperm plasma membrane with outer acrosomal membrane
• allows for the release of acrosomal enzymes that allow the sperm to penetrate the oocyte zona pellucida

Question 9

During a macroscopic evaluation, what components of the semen are evaluated?

Answer 9

• semen volume
• color
• odour
• viscosity
• pH
• semen concentration
• debris

Question 10

During a microscopic evaluation, what components of the semen are evaluaton?

Answer 10

• motility: percent motile, motility rating, motility pattern
• morphology

Question 11

What is the optimal motility rating and motility pattern for semen?

Answer 11

Motility rating = rapid progression
Motility patterns = linear progression

Question 12

What is the fxn of accessory sex glands?

Answer 12

Glands of the male reproductive tract that contribute the seminal plasma (fluid) to semen

Question 13

What are the 4 accessory sex glands?

Answer 13

1. ampulla
2. vesicular gland
3. prostate gland
4. bulbourethral gland

Question 14

Ampulla

Answer 14

• enlargement of the ductus deferes that connects to urethra
• doesn’t contribute any fluid but helps with mixing

Question 15

Vesicular gland (seminal vesicles)

Answer 15

paired dorsal cranial glands that empty directly into urethra

Question 16

Prostate gland

Answer 16

• gland found at the jxn of the urinary bladder and urethra
• 2 prostate forms
  1. Corpus Prostate = lies outside the urethral m. and is visible as a distinct structure
  2. Disseminate Prostate = gland tissue is distributed along the walls of urethra and is not distinct

Question 17

Bulbourethral gland (cowpers)

Answer 17

paired glands located on either side of the urethra, which are composed of connective tissue

Question 18

In what 3 animals are all 4 male accessory glands present in?

Answer 18

bull, ram, stallion

Question 19

What animal only has a prostate?

Answer 19

dog

Question 20

What accessory sex gland does the boar NOT have?

Answer 20

ampulla

Question 21

What 2 accessory sex glands does the cat have?

Answer 21

• prostate
• bulbourethral gland

Question 22

What does the ampulla contribute to seminal plasma?

Answer 22

• nothing; serves as pre-ejaculate reservoir

Question 23

What do the vesicular glands contribute to seminal plasma?

Answer 23

• produces most the fluid to the ejaculate
• contributes energy substrate and buffers the semen

Question 24

What does the prostate gland contribute to the seminal plasma?

Answer 24

• produces fluid
• contributes inorganic ions- buffers the semen

Question 25

What do the bulbourethral glands contribute to the seminal plasma?

Answer 25

• produces fluid pre-ejaculate that flushes urine residues from urethra in most species
• produces gel-fraction in boars

Question 26

What are the 5 functional components of seminal plasma?

Answer 26

1. energy substrates
   - sperm need energy
2. sperm membrane maintenance
   - eliminate free radicals to maintain integrity of plasma membrane
3. Semen pH (slightly acidic)
   - created by citric acid
4. buffering capacity - osmolarity
   - to control pH
5. proteins
   - various forms, various fxns

Question 27

Is the composition of seminal plasma the same for every species?

Answer 27

No!
- there is variation and unique characteristics that affect the sperm in different ways

Question 28

What type of proteins is seminal plasma rich in?

Answer 28

• low molecular weight proteins = spermadhesins (adhere to the head of the sperm)

Question 29

What are the 3 important roles of seminal plasma proteins?

Answer 29

1. decapacitation factors
2. protease inhibitors
3. immune suppression