Copulation and fertilisation Flashcards
What is the first step in penile erection?
Visual/ Olfactory cues from the female
What do the parasympathetic nerve fibres fire?
NANC fibres that release NO
What does Nitrous oxide do?
Relaxes smooth muscle which causes vasodilation which then causes erection
What does the ischiocavernous muscle do?
prevents drainage of the blood entering the penis
What does the vas deferens do?
Contracts to move sperm to the urethra
What does contraction of the male accessory glands do?
Releases fluids/ plasma that then mix with the sperm
What does the Bulbospongiosus muscle do?
contracts to expel sperm/ urine
What are some adaptations to maintain sperm?
Direct insemination to the uterus, Maintaining position (bitch) and using a viscous ‘gel-like’ ejaculate
What is the cervixes adaptation to hold onto sperm?
They have crypts that sperm can be held in then released periodically
What is an adaptation of the uterus to move sperm along?
release of sperm causes release of oxytocin which stimulates contraction of the smooth muscle in the uterus
What is the entrance to the oviduct referred to?
Uterotubal junction
What is capacitation?
Final Maturation of the sperm
What is the acrosome reaction?
A series of changes where the acrosomes on the sperm (enzymes) break down the outer layer of the sperm allowing it to fuse with the zona pellucida
What does the sperm release once it has entered the zona pellucida and attached to the microvilli?
Cortical granules, these form a layer which prevents any more sperm from entering the oocyte
What occurs in the oocyte after fertilisation?
Another polar body is formed containing half of the genetic information so the oocyte becomes haploid
What is syngamy?
Fusing of the male and female genetic information so that it becomes a zygote
What reaches out from the oocyte to fuse with the semen?
Microvilli
fuses with inner acrosomal membrane once it has been revealed
What part of the penis will the blood enter?
corpus cavernosum (spongy/air filled)
Why is sperm motility important?
Helps drive the sperm through the zona pellucida
When will the cervix release sperm from the crypts?
only In the absence of progesterone
What hormone will cause the uterus to contract?
Oxytocin, after being released from the posterior pituitary
Describe capacitation
1) epididymal proteins and carbs are added to the outer membrane of the sperm
2) seminal plasma from accesory glands coats the zona pellucida receptors
3) proteins and seminal plasma is lost therefore the zona pellucida receptors are revealed
When does seminal plasma cover the sperm head?
at what point during ejaculation
post-ejaculation
When are the proteins lost from the head of the sperm?
Once the sperm has entered the uterus
What is the corona radiata?
outer layer of the oocyte
helps to provide protection
How do bitches, Mares and Sows improve sperm retention?
The sperm is directly inseminated into the uterus
What is one adaptation that bitches have to improve sperm retention?
They maintain their position
What is one adaptation to ejaculate in stallions, boars and rodents?
Their ejaculate is a ‘viscous gel’
What is the sperm storage time in the cervix for different species?
- Pig – 6 days * Human – 4 days * Horse – 6 days * Bat – 1 year
What is the function of polyspermy?
To prevent/ block polyploidy
What is the oestrus length for a mare?
7 days
What is the oestrus length for a cow?
18 hours
What is the oestrus length for a bitch?
9 days
What is the oestrus length for a pig?
50 hours
What is the oestrus length for a sheep?
30 hours
What is the function of the bulbospongious muscle in penile erection?
aids to maintain erection by increasing pressure in the bulb of the penis
What is the function of the ischiocavernhous muscle in penile erection?
Contracts to push blood from the crura into the cavernous muscle
