Midterm 2 - Lecture 18 Flashcards
3 major structures of the sperm head
- nucleus
- oval and flattened
- DNA is highly condensed - Acrosome
- membrane-bound lysosome containing hydrolytic enzymes required for penetration of the oocyte zona pellucida at fertilization - Post-nuclear cap
- lower portion of sperm head not covered by acrosome
What is the tail axoneme responsible for?
- 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
Sperm metabolism
- sperm motility indicates its metabolic state
- energy required for motility is derived from substrates in the seminal fluid
For how long is sperm viable in the epididymus vs ejaculation?
Epididymus
- no O2 or energy substrates
- sperm is viable for DAYS
Ejaculation
- O2 and energy available
- sperm is viable for HOURS
What is sperm capacitation?
- the process whereby sperm acquire fertility through interactions with the female reproductive tract
Why is sperm capacitation necessary?
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
What events occur during sperm capacitation?
- 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
What is the acrosome reaction?
- 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
During a macroscopic evaluation, what components of the semen are evaluated?
- semen volume
- color
- odour
- viscosity
- pH
- semen concentration
- debris
During a microscopic evaluation, what components of the semen are evaluaton?
- motility: percent motile, motility rating, motility pattern
- morphology
What is the optimal motility rating and motility pattern for semen?
Motility rating = rapid progression
Motility patterns = linear progression
What is the fxn of accessory sex glands?
Glands of the male reproductive tract that contribute the seminal plasma (fluid) to semen
What are the 4 accessory sex glands?
- ampulla
- vesicular gland
- prostate gland
- bulbourethral gland
Ampulla
- enlargement of the ductus deferes that connects to urethra
- doesn’t contribute any fluid but helps with mixing
Vesicular gland (seminal vesicles)
paired dorsal cranial glands that empty directly into urethra
Prostate gland
- 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
Bulbourethral gland (cowpers)
paired glands located on either side of the urethra, which are composed of connective tissue
In what 3 animals are all 4 male accessory glands present in?
bull, ram, stallion
What animal only has a prostate?
dog
What accessory sex gland does the boar NOT have?
ampulla
What 2 accessory sex glands does the cat have?
- prostate
- bulbourethral gland
What does the ampulla contribute to seminal plasma?
- nothing; serves as pre-ejaculate reservoir
What do the vesicular glands contribute to seminal plasma?
- produces most the fluid to the ejaculate
- contributes energy substrate and buffers the semen
What does the prostate gland contribute to the seminal plasma?
- produces fluid
- contributes inorganic ions- buffers the semen
What do the bulbourethral glands contribute to the seminal plasma?
- produces fluid pre-ejaculate that flushes urine residues from urethra in most species
- produces gel-fraction in boars
What are the 5 functional components of seminal plasma?
- energy substrates
- sperm need energy - sperm membrane maintenance
- eliminate free radicals to maintain integrity of plasma membrane - Semen pH (slightly acidic)
- created by citric acid - buffering capacity - osmolarity
- to control pH - proteins
- various forms, various fxns
Is the composition of seminal plasma the same for every species?
No!
- there is variation and unique characteristics that affect the sperm in different ways
What type of proteins is seminal plasma rich in?
- low molecular weight proteins = spermadhesins (adhere to the head of the sperm)
What are the 3 important roles of seminal plasma proteins?
- decapacitation factors
- protease inhibitors
- immune suppression
