01-15: Transport of Gametes Flashcards
What is the status of the graafian follicle at pre-ovulation?
mature graafian follicle
What is the status of the oocyte at pre-ovulation?
oocyte arrested in Diplotene of Prophase I
What causes expansion of the follicle at pre-ovulation?
FSH and LH
What is the status of the oocytes progress through Meiosis I and II at pre-ovulation?
- Meiosis I = complete
- Arrested at Metaphase II
What is the status of the stigma at pre-ovulation?
formation of stigma
What happens pre-ovulation?
1- Mature graafian follicle 2- Oocyte arrested in Diplotene of Prophase I 3- Expansion of follicle by FSH and LH 4- Completion of meiosis I 5- Arrest at metaphase II 6- Formation of stigma
What happens at ovulation (Day 14)?
1- LH surge from anterior pituitary
2- Increased blood flow to follicle wall
3- Thickening of outer layers of follicle
4- Release of fluid/other compounds from BV
5- Local production of matrix metalloproteinases
6- Secretion of HA from cumulus cells
7- Inflammatory action (rupture of follicle wall)
What are the fluids and other components that are released at ovulation from BV?
- Edema
- Prostaglandins
- Histamine
- Vasopressin
- Plasminogen activator
What do the matrix metalloproteinases do?
degrade extracellular matrix
When does the inflammatory action causing rupture of follicle wall occur during ovulation?
about 24 hours after the LH surge
What is ovulated?
- Ovum at Metaphase II
- ZP
- Corona radiata
- Expanded cumulus oophorus
What happens when the fimbriae of the uterine tube move closer to the ovary and sweeps across the surface?
- Ciliation of tube epithelial cells INCREASES
- Activity of tubal smooth muscle cells INCREASES
What transports the egg through the uterine tube?
contractions of smooth muscle
How long does it take the egg to transport through the ampulla?
72 hours (slow transport)
How long does it take the egg to transport through the isthmus?
8 hours (rapid transport)
What does the rapid transport of the egg through the isthmus require?
progesterone
How many days does it take the egg to arrive at the uterus?
3-4 days
How many days for:
- Implantation
- Blastocyst
- Morula
- Cleavage
- Implantation = 6 days
- Blastocyst = 4 days
- Morula = 3 days
- Cleavage = 1 day
After spermiogenesis, what 3 kinds of transport does the sperm use?
- passive transport (via testicular fluid)
- smooth muscle contractions
- seminiferous tubule cilia
Where does the sperm travel through after spermiogenesis?
- Through Rete testes (network of tubules)
- Through Efferent ductules (Efferent pathway)
- To Head of epididymis (highly coiled)
What are the steps of sperm transport in the male?
1- Passive transport to Epididymis via testicular fluid
2- Maturation in Epididymis (2 weeks)
3- Rapid transit through Ductus Deferens
4- Addition of fluid from Seminal Vesicle
5- Addition of Prostatic fluid
What are the steps of sperm transport in the female?
1- Sperm deposited in upper vagina (increase pH)
2- Cervix
3- Uterus
4- Uterine tubes
5- Up uterine tube by swimming and contractions of the tube
6- Small number of sperm near egg at a given time
What happens during the sperm maturation in the head of the epididymis (12 days)?
Sperm head plasma membrane changes in glycoproteins (incapacitation)
When are sperm capable of fertilization?
by the time they reach the tail of the epididymis
What are the sperm ejaculated through?
Ductus deferens
What are the additional fluid secretions that are ejaculated?
- Fructose
- Prostaglandins
- Citric acid
- Zn
- Mg
- Phosphatase
What secretes Fructose and Prostaglandins?
Seminal vesicles
What secretes Citric acid, Zn, Mg, and Phosphatase?
Prostate
What buffers the acidity of vaginal fluids in the upper vagina?
seminal fluid
What is the pH change in the upper vagina due to sperm transport?
4.3»_space; 7.2
What is the pH in the cervix?
6.0-6.5
Optimal for sperm motility
How does the mucous block in the cervical canal change during mid cycle?
- composition and viscosity of mucous changes
- thick»_space; thin and watery
Some spermatozoa reach the uterine tubes within _________ minutes following ejaculation
5-20 minutes
Initial rapid transport
These sperm = NOT as capable of fertilizing egg
What does the initial rapid transport of sperm rely most on?
muscular movements of the female tract
What does slow sperm transport involve?
sperm swimming through cervical mucous
How fast does sperm move through the cervical canal during slow transport?
2-3 mm per hour
Where is sperm stored during slow transport?
in cervical crypts
How long can it take for the sperm to reach the oviducts during slow transport?
2-4 days
What is the isthmus the site of?
capacitation
What happens to the sperm after release following capacitation?
sperm move up the oviduct by:
- Swimming movements
- Peristaltic contractions
Where does fertilization occur?
ampulla
What happens to the membrana granulosa during the formation of the corpus luteum?
it breaks down
Where do BV grow during the formation of the corpus luteum?
into the cavity of the ruptured follicle
What causes the growth of BV into the cavity of the ruptured follicle?
External thecal cell angiogenic factor release
What causes the leutinization of granulosa cells?
granulosa lutein cells = secrete increasing amounts of progesterone and some estrogen
How does the corpus luteum breakdown in the absence of fertilization late in the menstrual cycle?
- Apoptosis
- Uterine luteolytic factors
How is the corpus albicans formed from granulosa lutein?
the granulosa lutein cells are replaced with collagenous scar tissue
What is the fate of the corpus luteum if pregnancy occurs?
- it is maintained by HCG from future placental tissues
- granulosa lutein cells are replaced by theca lutein cells
- it remains functional until after the 1st trimester
What is capacitation required for?
sperm to undergo acrosomal reaction
Where does capacitation occur?
in the isthmus in the uterine tube
What does capacitation require?
binding of sperm to tubal epithelium
What are the steps of capacitation?
1- Cholesterol removed from sperm surface
2- Glycoproteins from epididymis are removed
3- Period of hyperactivity
4- Release of sperm in small numbers
Removal of cholesterol from the sperm surface inhibits _____________
premature capacitation
