Lecture 5 Flashcards
What are the constituents of the ejaculate
- Fructose or sorbitol
- Buffers and coagulator secretions
- Reducing agents
- Prostaglandins
What is the function of fructose or sorbitol
Nutritional support
What is the function of buffers and coagulator secretions
Neutralize acidic pH of vagina and facilitate gel formation/clotting of ejacuate
What is the function of reducing agent
protect against oxidation
What is the function of prostaglandins
may stimulate contraction of female tract
What are the steps of sperm transport (5)
- Vaginal, cervical or uterine insemination
- Pass cervic/mucus barrier
- Traverse uterus
- Pass UTJ barrier and initiate capacitation and hyper mobility
- acrosome react and fertilise oocyte
What does the prostigladins in semen stimulate
Uterine contractions
Where does a lot of sperm get trapped
Crypts and glands
What is the function of vaginal plugs in rodents (4)
- facilitates passage of sperm and seminal proteins into uterus shortly after coitus
- Prevents sperm loss from vagina
- prevents mating by other animals
- Plug lost within a few hours of mating
Where is the sperm reservoir
In the isthmus
Where do sperm attach to in the oviductal isthmus
Epithelial cells
Can sperm immediately fertilise an egg
No, they need to spend time in the female reproductive tract to trigger hyperactive motility
What is the process involved in getting hyperactivity (2)
- Removal of protein coating acquired in epididymis
2. Reorganization of plasma membrane to expose binding sites
What is the acrosome reaction
Swelling of acrosome and fusion of outer acrosomal membrane with overlying plasma membrane
What is the calcium dependent event in the autosome reaction
Increase intracellular Ca2+ and cAMP
Explain the process of fertilisation
- A sperm reach perivitelline space and fuses with oocyte plasma membrane
- Fusion triggers Ca2+ waves causing cortical granule release
- Meiosis resumes -> 2nd polar body extruded and sperm nucleus decondenses
- Male and female pronuclei breakdown and chromosome combine -> syngamy
Why are there changes to to zona pellucid after penetration of a sperm
Prevents entry of more sperm
What are released into the perivitelline space that harden the zona
Cortical granules
What happens when sperm attach to epithelial cells
Form a sperm reservoir
What enzymes are released by acrosome (2)
- Hyaluronidase
2. Acrosin
What is the function of hyaluroidase
Cumulus cell penetration
What is the function of acrosin
Zona pellucida digestion
What do seminal vesicle proteins mix with to form clotting
Transglutaminase
Describe the process of fertilisation
Sperm enter the oviduct and the isthmus and sperm attach to the epithelial cells at the isthmus and form a collection. The sperm is the stripped of proteins and gain hyperactivity where it moves to the ampulla and it undergoes an acrosome reaction in order to fertilise the egg
