Physiology 2130 Lecture Notes - Lecture 70: Granulosa Cell, Oocyte, Glycogen
1 May 2018
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Lecture 070: Fertilization and early development
Window of Opportunity for Conception
● Sperm are viable for 1-2 days (48 hours)
○ Sometimes they survive up to 4 days
● Ovum are viable for 6-12 hours
● Fertilization occurs in the ampulla
● Sperm transport
○ Rapidly enter the vagina,
uterus and into the ampulla
of the fallopian tube in about
20 minutes
○ Amount of sperm rapidly
decreases
■ From 250,000,000 in
the vagina to 50 in the
ampulla
○ Trip is fraught with heavy
mortality
○ Average human ejualation
contains over one hunded
million sperm by only about
0.002% complete the journey
○ And only 1 can fertilize an ovum
● Ovum transport
○ Takes much longer
○ Takes about 7 days to move from the ampulla of the fallopian tube to the uterus
after fertilization
○ Morula implants at around day 7 after fertilization
● Cumulus oocyte complex
○ Oocyte with the granulosa cells (corona radiata) around them
○ Expelled from the follicle during ovulation)
○ Under the influence of estrogen the fallopian “waves” the oocyte into the tube
Estrogen Actions
● Promotes actions that are favourable for sperm movement and oocyte binding
● Active in the fallopian tube to promote ciliary actions and contractions of the smooth
muscles (myometrium) that move the oocyte/embryo into the uterus
● Decrease the viscosity of mucus at the cervix
○ Lets the sperm pass
● Increase production of glycogen in the vagina
○ Glycogen metabolism produces lactic acid which decreases the pH (increase
acidity)
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■ This is a method of protection against infection and kills the remaining
sperm in the uterus
■ Most sperm is protected with its alkaline seminal secretions
Progesterone Actions
● Opposite to the actions of estrogen most of the time
● Viscosity of the mucus at the cervix is not reduced
○ Acts are a barrier to the sperm
Sterilization in Females
● Tying tubes
● Prevents the ovum from moving to where it wants to and prevents it from entering into
contact with sperm
Capacitation
● Functional maturation of sperm
● Needed for fertilization
● Majority is completed in the female reproductive tract prior to fertilization
● 2` things occur:
○ Plasma membrane destabilizes in the acrosomal sperm head via
cholesterol removal
● Becomes more porous
■ This is done in preparation for fusing
● Allows it to penetrate the outer layer of the ovum
■ This destabilization is also associated with a Ca2+ influx and an increase
in cAMP
● Drives the mitochondria and channels in the membrane
○ Leads to hyperactivity in the sperm’s tail
■ Propulsion mechanism is greatly improved
● Increase sperm motility
● Wave like to whip like motion
○ Intracellular alkalinization (activation) of the sperm
■ cAMP leads to activation of channels in the membrane
● Increased HCO3- enters the cell (HCO3- was added from the
seminal fluid)
■ Increase sperm metabolism
■ Increase sperm motility
● Recall
○ Fluid added to the sperm by accessory glands dilutes the sperm
Fertilization
● Sperm has to get through the granulosa cells (corona radiata) and zona pellucida
○ Proteolytic enzyme helps break down those layers
■ Hyaluronidase (granulosa cells)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Sperm are viable for 1-2 days (48 hours) Sometimes they survive up to 4 days. Rapidly enter the vagina, uterus and into the ampulla of the fallopian tube in about. From 250,000,000 in the vagina to 50 in the ampulla. Average human ejualation contains over one hunded million sperm by only about. And only 1 can fertilize an ovum. Takes about 7 days to move from the ampulla of the fallopian tube to the uterus after fertilization. Morula implants at around day 7 after fertilization. Oocyte with the granulosa cells (corona radiata) around them. Under the influence of estrogen the fallopian waves the oocyte into the tube. Promotes actions that are favourable for sperm movement and oocyte binding. Active in the fallopian tube to promote ciliary actions and contractions of the smooth muscles (myometrium) that move the oocyte/embryo into the uterus. Decrease the viscosity of mucus at the cervix. Glycogen metabolism produces lactic acid which decreases the ph (increase acidity)
