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What are the female Gonadotropins?
Lutenizing Hormone (LH) and Follicle Stimulating Hormone (FSH)
What effect does the production of estrogen have?
stimulates the endometrium to enter the Proliferative Phase
How soon before ovulation does the Secondary oocyte arrest its meiotic division?
3 hours
How is the oocyte removed from the ovary in ovulation
Follicular sweeping and contractions in the ovarian wall
After ovulation, what is the fate of the Granulosa Cells of the Oocyte?
they become vascularized and are transformed into yellow Lutein Cells.
What structure do Lutein Cells become?
Corpus Luteum
What constitutes the large size of the Corpus Luteum?
hypertrophy and accumulation of lipids
What is the function of the Corpus Luteum?
Secretion of estrogen and progesterone
What is responsible for the production of progesterone by the oocyte?
Corpus Luteum
When do females begin to undergo monthly cycles?
At puberty
What controls female reproductive cycles?
The Hypothalamus
What role does the hypothalamus play in female reproductive cycles?
It releases GnRH, which stimulates the pituitary gland to release Gonadotropins
What do gonadotropins do?
they stimulate and control changes in the ovary
What is the role of FSH in the ovary?
it stimulates 15 - 20 follicles to grow and mature
How many follicles reach full maturity and are released from the ovary?
1
What hormone is produced from a growing follicle?
Estrogen
What effect does the surge of LH have?
Causes primary oocyte to complete meiosis I and begin meiosis II
Causes progesterone to be produced
Causes ovulation
What triggers Progesterone to be produced?
surge in LH
What triggers ovulation?
surge in LH
What phase of Meiosis II is the secondary oocyte arrested in before ovulation?
Metaphase II
What causes the endometrium to enter the Secretory Phase?
Progesterone production
At what Phase is the uterus at the time of ovulation?
Secretory Stage
When does a fertilized oocyte reach the uterine lumen?
3-4 days
What is the fate of the Corpus Luteum if no fertilization occurs?
it shrinks after 9 days and becomes scar tissue
What is the scar tissue that is formed on an unfertilized oocyte?
Corpus Albicans
What is the fate of the endometrium if no fertilization occurs?
it enters the Menstrual Phase due to the decrease in progesterone.
What causes the decrease in progesterone of an unfertilized oocyte?
Shrinking of the Corpus Luteum, which secretes progesterone
What is the fate of the Corpus Luteum if fertilization occurs?
it is prevented from shrinking by Human Chorionic Gonadotropin
What secretes Human Chorionic Gonadotropin?
syncytiotrophoblast
What does the maintained Corpus Luteum develop into?
Corpus Luteum of Pregnancy
What is the function of the Corpus Luteum of Pregnancy?
to produce progesterone until the fourth month
What produces progesterone after the fourth month of pregnancy?
The trophoblastic component of the placenta
What occurs of the Corpus Luteum of Pregnancy is removed before the fourth month?
Abortion
Where does fertilization occur?
Ampulla
Why is the ampullay tube the most suitable region for fertilization?
it is the widest part of the tube and closest to the ovary
How do sperm move from the cervix to the uterine tube?
the are moved by uterine muscle contractions
How long does the trip from the cervix to the uterine tube usually take?
30 minutes to 6 days
When do sperm become less motile?
At the isthmus
How do sperms become motile again after leaving the Isthmus
Chemoattractants make them motile and swim to the ampulla
What are the key processes for sperm to undergo before being able to fertilize an oocyte?
Capacitation
Acrosomal Reactions
How long does the process of Capacitation last?
7 hours
What occurs during capacitation?
Glycoprotein coat and Seminal plasma proteins are removed from the plasma membrane
Where does capacitation occur?
uterine tube
When does the Acrosome Reaction Occur?
After binding to Zona Pellucida
What induces the Acrosome reaction?
Zona Proteins
What occurs during the Acrosome Reaction?
Enzymes, Acroson and Trypsin like substances are released
What is the Zona Pellucida?
the glycoprotein shell surrounding plasma membrane of an oocyte
What is the function of the Zona Pellucida?
facilitates the binding of sperm and the acrosome reaction
What mediates the binding of sperm and triggers the acrosome reaction?
ZP3 ligand
What allows the sperm to penetrate the Zona Pellucida and make contact with the oocyte plasma membrane?
Acrosomal Enzymes
What occurs when the head of the sperm contacts the oocyte surface?
the permeability and composition of the zone pellucida changes
lysosomal enzymes are released from cortical granules and prevents sperm penetration and receptor inactivation
What are the three phases of fertilization?
Penetration of the Corona Radiata
Penetration of the Zona Pellucida
Fusion of the Membranes
What mediates the adhesion of the sperm to the oocyte?
Integrins on the oocyte and disintegrins on the sperm
What occurs after the sperm adheres to the oocyte?
plasma membranes fuse
How does the oocyte respond to the entering of sperm?
Cortical and Zonal Reactions
Resumption of Meiosis II
Activation
What important event of fertilization prevents Polyspermy?
the Coronal and Zonal reactions
What is the result of the oocyte's second meiotic division?
a second Polar Body and a definitive oocyte
the female pronucleus is also produced
What are the three main results of fertilization?
restoration of the diploid chromosome number
determination of sex
initiation of cleavage
What is cleavage?
a series of mitotic divisions where the zygote increases its number of cells
What kind of cells increase in number via mitosis and become smaller with each division?
Blastomeres
What is Compaction?
the process of blastomeres forming a compact ball and maximize contact with one another
What holds compact cells together?
tight junctions
What is a morula?
a 16-cell embryo
when is a morula formed?
3 days after fertilization
When does a morula become a blastocyst?
as it enters the uterine cavity
What is the blastocoel?
the fluid-filled cavity in the blastocyst.
What are the inner cells of the Blastocyst called?
the Embryoblast
What are the outer cells of the Blastocyst called?
the Trophoblast
When does the zona pellucida disappear?
day 6
When can implantation begin?
When the Zona Pellucida disappears and allows the trophoblastic cells to penetrate the uterine epithelial cells
What mediates the attachment of the trophoblast to the epithelium?
L-Selectin on the trophoblast and the carbohydrate receptors on the oocyte
What further allows the attachment and invasion of the Blastocyst?
Integrins
What Phase is the endometrial wall in during implantation?
Secretory Phase
What are the three Uterine Layers?
Endometrium
Myometrium
Perimetrium
What are the three phases the Endometrium goes through during the Menstrual Cycle?
Proliferative Phase
Secretory Phase
Menstrual Phase
When does the Proliferative Phase occur?
after the Menstrual Phase
What occurs during the Proliferative Phase?
Follicle growth due to Estrogen
regeneration of glands and arteries
What Initiates the Secretory Phase?
Progesterone
Under what conditions does the Menstrual Phase occur?
only if there is no fertilization
When does the Secretory Phase occur?
2-3 days after ovulation
What are the 3 endometrial layers?
Compact Layer
Spongy Layer
Basal Layer
When does the Menstrual Phase occur?
3-4 days after ovulation
What occurs during the menstrual phase?
the compact and spongy layers of the endometrium are shed
there is diapedesis of blood from venues and superficial arteries which are expelled
glands and storm are expelled
What regenerates after menstruation?
the basal layer of the endometrium during the proliferative phase
What is the role of the endometrium when fertilization occurs?
Assists with implantation and the formation of the placenta.
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