Physiology 3120 Lecture Notes - Lecture 67: Fallopian Tube, Ampulla, Semen Analysis
15 May 2018
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Lecture 67 – Fertilization
Window of opportunity – conception
- Sperm is viable for 1-2 days (48 hours) and they can hang around for up to 4 days
- Oocyte is more conservative and can last between 6-24 hours
- Fertilization occurs in the ampulla of the fallopian tubes
- Oocyte stays within the ampulla for a period of time
Gametes – finding each other with chemicals and temperature
- Sperm transport
o Sperm enters from the vagina and rapidly travels through uterus into fallopian
tubes to the ampulla
o Moving further into the reproductive tract, the sperm count diminishes
o Time is very rapid
- Oocyte transport:
o Takes longer than sperm (slow)
o Moves from the fallopian tube → uterus
o Ampulla is where fertilization takes place and it is a slow movement down the
fallopian tube
o Morula is where the fallopian tube enters the uterus
o It takes a couple days before it implants
o Implantation occurs 7 days after fertilization
- Cumulus oocyte complex:
o Oocyte with granulosa cells + corona radiate lying around it
o Cells expelled from the follicule during ovulation
- Under effects of estrogen, fimbrae reach over the ovaries to wave the oocyte into the
fallopian tube
- LOCATION OF GAMETES + RELATIONSHIP WITH TIME!!!
find more resources at oneclass.com
find more resources at oneclass.com
Estrogen and sperm
- Fertilization occurs after ovulation where progesterone rises and estrogen declines
- In the process, estrogen has set things in play to ensure that ovulation works and gametes
get together
- Estrogen actions:
o Ampulla + fimbriae: contraction of cilia to wave oocyte complex into fallopian tube
o Contraction of smooth muscle propels oocyte and embryo into uterus
o Contraction of myometrium (uterus muscular layer)
o At the top of the cervix, it decreases the viscosity of mucous (don’t want it make it
difficult for sperm to move)
o Promotes production of glycogen → when it is metabolized, it produces lactic acid
and reduces in increase in acidity to prevent infection and kill sperm (sperm do not
like acid) → kills nonsuccessful sperm that did not make it to the uterus from cervix
- Sperm with seminal secretions was well protected from the alkaline secretions (this gives it
some protection but it must get into the cervix where mucous is decreased)
- The actions of progesterone are reverse of estrogen
o Viscosity is not reduced (barrier to sperm) (estrogen is important to getting through
and for the sperm to find the oocyte)
- Estrogen changes body fluids and involved in muscular contractions to put sperm and
oocyte together
find more resources at oneclass.com
find more resources at oneclass.com
Getting there – the guys story part
- The trip is also fraught with heavy mortality
- Millions of sperm die and only a few make it the ampullary region
- An average human ejaculate contains over one hundred million sperm, but only a few dozen
(0.002%) complete the journey
- One sperm is successful
Female – tubes tied
- Men: cut vas defens → stops gamete movement from where you want it to go
- Females get tubes tied
o Stop gametes from moving to where you want and from meeting sperm
Capacitation
- Before the sperm can fertilize the egg, it undergoes changes to perform its function
o Sperm matures in epididymis and after ejaculation, once it is in the female
reproductive tract, before it can fertilize it must undergo capacitation
- Completed in the female reproductive tract (little before it leaves male) prior to fertilization
Alters:
- 1. Acrosomal Sperm Head plasma membrane destabilization (prep for fusing, eg; Chol
removal)
o Head undergoes destabilization and becomes porous
o Increase in porosity is through cholesterol removal from the membrane
o Destabilization is associated with increase in Ca influx → promotes cAMP
- 2. Sperm motility (Ca2+ influx (cAMP) = wave like to whiplash motion = hyperactivity)
o Drive mitochondria = hyperactivity of sperm tail
- DESTABILIZATION OF MEMBRANE + INCREASE ACTIVITY IN TAIL = PROPULSION
MECHANISM IS IMPROVED
- CAPACITATION IS NEEDED FOR FERTILIZATION
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Sperm is viable for 1-2 days (48 hours) and they can hang around for up to 4 days. Oocyte is more conservative and can last between 6-24 hours. Fertilization occurs in the ampulla of the fallopian tubes. Oocyte stays within the ampulla for a period of time. Gametes finding each other with chemicals and temperature. Sperm transport: sperm enters from the vagina and rapidly travels through uterus into fallopian tubes to the ampulla, moving further into the reproductive tract, the sperm count diminishes, time is very rapid. It takes a couple days before it implants. Cumulus oocyte complex: oocyte with granulosa cells + corona radiate lying around it, cells expelled from the follicule during ovulation. Under effects of estrogen, fimbrae reach over the ovaries to wave the oocyte into the fallopian tube. Location of gametes + relationship with time!! Fertilization occurs after ovulation where progesterone rises and estrogen declines.
