Prefertilisation sperm events Flashcards
(45 cards)
Where is sperm deposited in the ewe?
Vagina
Where is sperm deposited in the cow?
Vagina
Where is sperm deposited in the mare?
Uterus
- Initially deposited in cranial vaginally but will flow through open cervix to uterus
Where is sperm deposited in the sow?
Cervix/uterus
- Corkscrew penis and counter-corkscrew cervix, engage during copulation, long tract
Where is sperm deposited in camelids?
Uterine/cervix/vagina
Where is sperm deposited in the bitch?
Vagina (a lot will end up in uterus due to open cervix)
Describe structure and function of the head of spermatozoa
- Contains nucleus/DNA
- Acrosomal enzymes
Describe structure and function of the middle piece of spermatozoa
- Full of mitochondria
- ATP generation
- Microtubules
Describe the structure and function of tail of spermatozoa
- Propels sperm/movement
- 3mm minimum
- Allows for directional movement
What features develop as part of the maturation process in the epididymis?
Develop the ability to be motile
- The ability to fertilise
- cytoplasmic droplets
What features are acquired in the head of the epididymis?
The ability to move and fertilise
Where does the cytoplasmic droplet develop?
Throughout the migration of the sperm through the epididymis
Explain the importance of the epididymal tail
- Can store a large number of spermatozoa
- Allows more frequent ejaculation
How do sperm move?
- rotation of head
- Tail moving in wave like motion top to bottom
- Low amplitude initially
Describe the structure of the flagella of sperm
- Dentral axoneme with dyneins running length of flagellum
- Outer dense fibres surrounding axoneme in midpiece and central piece
- Fibrous sheath in principle piece
- Mitochondrial sheath in midpiece
Describe the structure of the central axoneme
- Anchored in centriole
- has pair of central microtubules
- Outer ring of 9 pairs of outer microtubules (symmetrical)
- Dyneins bound to each outer doublet
Explain how the dyneins work to make the flagellum move following ejaculation
- Bind to each outer double
- Extend motor domains towards adjacent outer doublet
- Outer doublets slide over each other
- Leads to bending of axoneme
Describe hyperactivated movement of spermatozoa
- Moves asymmetrically, high amplitude, straight in oviductal mucus, whiplash
- Facilitates sperm-oocyte contact
- Go in circles
When does hyperactivated movement of the sperm occur?
After capacitation
What is the function of the seminal plasma?
- Not essential for fertilisation
- Aids transport of sperm through urethra of male and then female tract
How does seminal plasma carry out its function?
- Nutritional support (fructose, glucose in horse)
- Buffering capacity
- Antioxidants (ascorbic acid)
- Prostaglandins
What is the function of the prostaglandins in the seminal plasma?
- Stimulates muscuar activity in female tract
- May help move sperm towards uterus
- Cervix may filter out some PGs
Give an overview of the journey taken by the spermatozoa following copulation
- Immediate transport
- Cervix
- Tansport through uterus
- Oviduct
- Fertilisation
How can spermatozoa be lost following copulation?
- Retrograde transport
- Phagocytosis after period of time
- Loss through vagina and vulva
- Once sperm enters uterus, recognised as foreign so induces immune response
- Neutrophil infiltration into uterus following insemination rapid