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Title: Sperm Transport Fertilisation.
Description: University notes on Sperm Transport Fertilisation.
Description: University notes on Sperm Transport Fertilisation.
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Sperm transport, fertilisation and
early embryo development
Sperm Transport
•
Humans
•
Most are lost via
_______________
– _____________
Lecture Overview
• Sperm Transport
• Fertilization
• Early Embryonic
Development
Ovulation
• Under the influence of oestrogen
• Fimbria surrounds the ovary
– ______________________
• Fingerlike projections in ___________________
– Contract rhythmically- oocyte drawn into _____________
• Sperm and oocyte unite here
– Post fertilisation zygote moves into isthmus & into uterus
1
Sperm transport
3 stages of sperm transport
1
...
Colonization of reservoirs
•
•
_________________
Endometrium
•
_______________
3
...
tract for at least _____ hours –
_____________________
Capacitation of Sperm
• __________________coats sperm’s plasma membrane
– From accessory gland secretions
– Stabilises sperm on journey
• Prevents premature acrosome reaction
– But interfere with fertilisation if present
• Biochemical event
– The uterus aids in the steps of capacitation
– Uterine fluids contain
• Albumin which binds cholesterol
• Lipoproteins
• Proteolytic and Glycosidasic enzymes
Sperm transport in the female tract
Pathways to Pregnancy and Parturition; Senger 2005
3
Hyperactivation
•
Removal of cholesterol
–
Rapid influx of Ca2+
1
...
Enable sperm to move _________________________
3
...
Fast Block to Polyspermy
• When fertilising sperm
contacts plasma membrane
• ____________________
– change in potential difference
across cell membrane
– rapid influx of sodium
Source: Google images
– blocks entry of other sperm
2
...
____________________
5
•
blocking entry of extra sperm
2
...
3 -4 days after fertilization the conceptus enters uterus
•
During this period it is nourished by secretions of uterine glan ds
–
The blastocyst remains unattached until after it hatches from ZP
•
Human – Day 5
•
Sheep – Day 6
•
Cattle – Day 7
Implantation/attachment
•
Implantation in rodents and humans invasive
– Blastocyst penetrates uterine mucosa
Implantation
•
Begins 6-7 days after fertilisation (in humans)
•
Cells of trophoblast contact uterine wall and adhere to it
•
This will only happen if a hospitable uterine environment is pre sent
– Correctly primed by oestrogen and progesterone
– Healthy – no disease process eg
Title: Sperm Transport Fertilisation.
Description: University notes on Sperm Transport Fertilisation.
Description: University notes on Sperm Transport Fertilisation.