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Endo/Repro Final > Fertilization And Implantation > Flashcards

Fertilization And Implantation Flashcards

1
Q

When does fertilization occur?

What does this allow for?

A

Day 15-16 of menstrual cycle

Recombination of genetic material and initiation of events that begin embryonic development

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2
Q

Where are do the sperm and the oocyte have to go to be fertilized?

What leads to follicular rupture?

What is ejected into the peritoneum?

What sweeps the oocyte into the oviduct?

A

Ampulla of oviduct

LH surge

Ovum and surrounding corona radiata

Fimbriae

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3
Q

The sperm enter the ____ near the uterus; 200 million reach the ____ of the oviduct.

What are the barriers the sperm face?

Cervical mucus and myometrium contractions are a result of increased ____ near ovulation period. This allows ____ to form to allow motile sperm to pass through; ____ help move sperm through the cervix/uterus.

A

Vagina; ampulla

Distance, immune, secretory, timing

Estrogen; channels; contractions

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4
Q

Sperm undergo ____ in order to fertilize the oocyte.

Where?

What are the modifications of spermatozoan caused by capacitation?

A

Capacitation

Female oviduct

Altered membrane fluidity due to removal of cholesterol

Removal of various proteins, carbs, and glycoproteins from the membrane that may block binding sites

Change in membrane potential that may permit Ca influx and the acrosome reaction

Phosphorylation of various proteins

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5
Q

Incapacitated sperm bind actively to epithelial cells of the ____. They become unbound when they are _____.

Binding slows the capacitation process, extends ___ lifespan, prevents too many sperm from reaching the ____, increased the probability the sperm will be in the ____ when the egg is ovulated; also called sperm ____.

A

Oviductal isthmus; capacitated

Sperm; egg; oviduct; reservoir

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6
Q

Hyperactivation of sperm is caused by what?

Involves a change in _____ motion from wavelike to ____. It is necessary for sperm to detach from the _____ epithelium. It increased the ____ in thick oviductal fluid and helps propel sperm through outer layers of the _____ and _____ of the egg.

A

Sperm capacitation and chemical signals from oocyte

Flagellar; whiplike; oviductal; mobility; cumulus and zona pellucida

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7
Q

Fertilization is a process by which multiple sperm bind to the ____ but only one fertilizes the ____.

What three barriers of the egg must be breached by the sperm?

A

Corona radiate; egg

Expanded cumulus (corona radiata)

Zona pellucida

Plasma membrane of the egg (oolemma)

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8
Q

The cumulus cell matrix is covered with ____; the sperm digest this with membrane bound _____.

A

Hyaluronic acid; hyaluronidase

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9
Q

What glycoproteins comprise the zona pellucida?

The sperm contain ____ receptors.

Binding of ZP3 receptor to ZP3 triggers ______. This causes the inner sperm membrane to fuse with the outer acrosomal membrane to release the contents of ____. The ____ receptors are lost and become ZP2

The enzymes in the acrosomal vesicle digest the _____ and sperm enter.

A

ZP1, ZP2, ZP3, ZP4

ZP3

Acrosome reaction

Acrosomal vesicle

ZP3

Zona pellucida

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10
Q

When the sperm reach the plasma membrane, they are involved with ___ proteins that bind to a sperm protein called ____. The entire ____ enters the edge during fusion, sperm DNA instantly _____.

What forms around the DNA and what is its fx?

A

Tetraspanin; Izumo

Sperm; decondenses

Membrane called pronucleus (stimulates the oocyte to begin its meiosis II process)

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11
Q

What are assisted reproductive techniques?

A

Ovulation induction

Artificial insemination (AI)

Gamete transfer

In-vitro fertilization (IVF)

Intracytoplasmic sperm injection (ICSI)

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12
Q

What triggers the cortical reaction?

What is released during this reaction?

What does this prevent?

What forms the physical barrier?

A

Fusion of sperm and egg

Release Ca, alteration of ZP2 -> ZPf, hyaluronic acid, proteoglycans, and proteinases

Blocks binding of additional sperm, preventing polyspermy

Zona pellucida

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13
Q

___ release stimulates the oocyte’s completion of meiosis II. This breakdowns ___ proteins and _____ is released.

When the egg is activated, ____ condenses. ____ forms around female chromosomes. Male and female chromosomes replicate as _____ move together. Fusion of pronuclei initiates ______.

A

MAPK; 2nd polar body

DNA; pronucleus; pronuclei; first embryonic cleavage (first embryonic development)

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14
Q

Describe the timing of pregnancy:

Day 0?
0-3 weeks?
3-8 weeks?
8 weeks-term?
Total gestation time?
A

Moment of fertilization

Early development

Embryonic period (organogenesis)

Fetal period

38 weeks

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15
Q

What happens during week one of embryonic development?

What happens on day 3?
Day 4?
Days 6-8?

A

Cleavage (cell division without growth)

Embryo reaches 16 cell stage (morula)

Early blastocyst

Implantation

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16
Q

During embryonic cleavage, individual cells become ____.

Mitotic divisions maintain ____ complement.

Blastomeres are ____.

Embryo reaches the 16 cell morula by day ____.

A

Blastomeres

2N (diploid)

Totipotent

3

17
Q

The outer cells of the morula increase cell to cell adhesion via ____ and ____.

They form ____ and increases Na and osmosis to form a _____.

Inner cells become inner cell mass and will form the ____ which is considered ____.

A

Desmosomes; tight junctions

Trophoectoderm; blastocele

Embryo proper; pluripotent

18
Q

What is a dizygotic twin?

What is monozygotic twinning and when do the cells usually divide?

What is caused during an early division of totipotent cells?

What is caused when there is a division of the inner cell mass?

What is caused when there is a incomplete division of the inner cell mass?

A

Female ovulates two oocytes and they are both fertilized

From one zygote; type of twinning depends on when there is a division in the cells, usually in the cleavage/blastocyst stage

Early division when the cells are totipotent = two individual embryos, same genetic material, each with own placenta

Division of the inner cell mass within blastocoele = share chorion, individual amniotic sacs or share sacs

Incomplete division of the inner cell mass = conjoint twins

19
Q

Embryo hatches from the _____ prior to implantation. ____ secrete proteases that digest the zona pellucida.

Inability to hatch results in _____. Premature hatching resulted in ____.

A

Zona pellucida; trophoblasts

Infertility; abnormal implantation

20
Q

What does the blastocyst synthesize and secrete?

Examples?

A

Molecules that promote the maintenance of pregnancy, promote implantation and placental development

Secretion of immunosuppressive and immunoregulatory factors, hCG

21
Q

What secretes human chorionic gonadotropin (hCG)?

When is this measured?

What is its fx?

A

Trophoblasts and syncytiotrophoblasts

8 days post ovulation

Prevents involution of the corpus luteum therefore preventing menstruation and allowing the corpus luteum to secrete progesterone and estrogen

Autocrine growth factor: stimulates trophoblast growth and development, stimulates placental growth

22
Q

Pre-implantation the blastocyst is bathed in ____. This draws O2 and necessary metabolic substances for ____ and ____. Exchange is via ____.

The blastocyst eventually needs a more intimate association with the uterus therefore develops the ____.

A

Uterine secretions; growth and survival; diffusion (O2/CO2)

Placenta

23
Q

Typical implantation occurs in the posterior wall of the ____.

This is an invasive, interstitial implantation with adhesion-supported invasion and migration of ____ cells. ____ enzymes break down the extracellular matrix.

The attachment of the blastocyst initiates differentiation of the _____. There are rapidly proliferating _____ that initially provide a feeder layer of continuously dividing cells.

A

Uterine fundus

Trophoblastic; hydrolytic

Trophoblast; cytotrophoblasts

24
Q

What are the fx of syncytiotrophoblasts?

They express ____ proteins that initially bind uterine and surface epithelia, then as the embryo implants, they bind to components of the ______.

They breakdown ____ through secretions of _____ and other hydrolytic enzymes.

They secrete ____, which maintains the viability of the corpus luteum for ___ secretion.

They are highly steroidogenic at ___ weeks and make enough ____ to maintain a pregnancy independent of corpus luteum.

As implantation and placentation progress, syncytiotrophoblasts fx in ____ and _____ of gases, nutrients, and wastes.

A

Adhesive (cadherins and intergrins); uterine extracellular matrix

Extracellular matrix; matrix metalloproteases

hCH; progesterone

10; progesterone

Phagocytosis; bidirectional placental transfer

25
Q

What are the stages of implantation?

A

Apposition

Attachment

Invasion

26
Q

What occurs during the apposition stage of implantation?

A

Contact between endometrium and trophoblasts in a crypt in the endometrium

Inner cell mass rotation near endometrial epithelium

27
Q

What occurs during the attachment phase of implantation?

What is decidualization?

A

Trophoblasts cells adhere to luminal endometrial epithelium

Interaction between surface proteins on trophoblasts and epithelial cells

Initiates changes in endometrial stoma (decidualization): increased vascular permeability, intracellular matrix composition, stromal cell morphology

28
Q

What happens during the invasion stage of implantation?

What protrudes through the basement membrane and reaches the endometrial stroma?

A

Degradation of endometrial epithelial cells

Trophoblast fusion and formation of syncytiotrophoblasts which are multinuclear, multicellular syncytium

Syncytiotrophoblasts

29
Q

As the syncytiotrophoblasts secrete _____ and ____ to increase invasion and degrade the matrix.

The primary metabolic substrates of degraded cells/matrix is taken up by the _____.

Finger-like projections reach maternal ____.

_____ becomes restored as the conceptus invades.

A

Metalloproteinases; angiogentic factors

Conceptus

Blood supply

Surface epithelium

30
Q

What decidualizaiton?

The endometrial stroma is transformed into enlarged and glycogen filled ____ cells.

The ____ is ready for the implantation of the embryo.

The decidua forms an epithelial-like sheet with ____ that inhibit the ____ of the implanting embryo.

Production of signals that prevent the embryo from invading the ____ and causing a ____.

A

Response of maternal stromal cells to invasion and progesterone

Decidual

Endometrium (decidua)

Adhesive junctions; migration

Myometrium; postpartum hemorrhage

31
Q

What is an ectopic pregnancy?

Where is it commonly found?

Is there a dicidual response?

A

Implantation somewhere other than uterine fundus

Oviduct

No; invasion is not controlled and can cause a rupture of the tissues and a hemorrhage

32
Q

What is placentation?

When does it occur?

What does it form?

A

Spaces appear within syncytiotrophoblasts

Day 9

Lacunae; break maternal capillaries; filled with endometrial secretions, maternal blood, digested matrix for nutrient transfer

33
Q

What is a primary villi?

Secondary villi?

Tertiary villi?

A

Proliferation of syncytiotrophoblasts and cytotrophoblasts to lacunae

Mesenchymal cells from the extraembryonic mesoderm invade the villi (chorionic membrane)

Mesenchymal cells from fetal blood vessels de novo

Endo/Repro Final (20 decks)

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