Copulation and Fertilisation Flashcards
lifespan of stored sperm?
they have a shorter lifespan - especially after freezing
what are the two main important behavioural factors for copulation?
Libido of male - physically capable?
Oestrus behaviour - ability to detect?
behaviour of male that is important for copulation?
physically capable, the drive to copulate, able to detect the female being in oestrus, functional sperm
what are the cues called that the males rely on to know when to copulate?
psychogenic stimulation
psychogenic stimuli - leads to erection of penis, how?
visual + olfactory cues from female
sensory nerves stimulate reproductive behaviour centre in hypothalamus
parasympathetic nerves fire (non adrenergic, non cholinergic NANC fibres - release NO)
Vasodilation of arterioles to penile corpora cavernosum penis
Erection
How is semen emitted?
signals being passed down sympathetic nerves (hypogastric in particular)
Leads to contraction of vas deferens
- sperm to urethra
Then contraction of male accessory glands
- Sperm mixed w/ seminal plasma
Semen to urethra
penis in vagina - what happens in order for ejaculation to occur?
sensory stimulation so signal back to nervous system - leads to spinal cord, there is a local reflex arc which is also sent up to the brain
Then contractions of muscles (urethralis, bulbospongiosus and ischiocavernous muscle)
Pulse like contractions
Wave of increasing pressure moves along penis pushing everything out of urethra - so pulses of ejaculation into female reproductive tract
Once sperm has been ejaculated - what are the 6 stages that have to happen?
Pass through cervix
Move through the uterus to reach the oviduct
Capacitate & hyperactivate
Traverse the cells of the corona radiate - to get to oocyte
Penetrate & bind the Zona pellucida
Fuse with the ovum
Immediate transport of sperm - some is lost - how?
retrograde loss - exit straight back out
phagocytosis - foreign
entrance into cervix/uterus
What is sperm retention promoted by?
Direct insemination - bitch, mare, sow
Maintain position - bitch
Viscous ‘gel’ like ejaculate fraction - stallion, boar, rodent
How is the window for fertilisation extended?
rapid transport - reach oviduct in minutes
Sustained transport
Cervical storage
Describe cervical storage?
sperm held in cervical crypts
Cervix only releases sperm in the absence of progesterone
Cervix selects against morphological abnormalities
storage time of sperm - in different species - pig, human, horse, bat?
*Pig –6days
*Human –4days
*Horse –6days
*Bat –1year
Capacitated sperm?
head of sperm coated in protein and carbs when in epididymis
some of these p&c coated - once sperm in female reproductive tract and capacitation triggered, these molecules are released and revealed to receptors found in Zona pellucida
Capacitation is necessary in order to fertilise oocyte
Capacitated sperm can?
is hyperactive and can fertilise
The fertilising sperm initiate what?
the ACROSOME reaction
What does the acrosome contain?
Hyaluronidase, Acrosin
‘Digest’ path through Zona pellucida
Acrosomal reaction?
release nucleus of sperm and fusion proteins
Fertilised oocyte?
ootid
how many polar bodies in ootid?
2
if 2nd polar body is forming it tells that fertilisation has occurred
Syngamy?
Formation of a zygote - individual has formed
Blastomeres?
2-celled embryo
4 –> 8 cells - now called?
Morula
All cells in morula are?
totipotent
