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Endocrine And Reproduction Exam #2 > Fertilization > Flashcards

Fertilization Flashcards

1
Q

When does fertilization occur?

A

Approx day 15-16

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2
Q

Where does fertilization occur?

A

Ampulla of oviduct

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3
Q

2 mechanisms of the female RT propelling sperm

A
  1. Causes cervix to produce watery mucus to help sperm enter uterus.
  2. Activates myometrial contractions to propel sperm.
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4
Q

What is capacitation and where does it occur?

A

Helps seem be capable of fertilizing egg.

Happens in oviduct.

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5
Q

What layers must sperm penetrate to get to the egg?

A

Corona radiata
ZP
PM of egg

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6
Q

What is the sperm-ZP3?

A

The sperm head attaching to the glycoproteins coat of ZP

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7
Q

How does the acrosome reaction occur?

A

Intracellular Ca2+ increases and causes the fusion of acrosomal membrane w/ sperm’s PM leading to exocytosis of acrosomal contents.

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8
Q

What is the cortical reaction? Caused by?

A

Caused by increased IC Ca2+ in oocyte. Leads to release of granules w/ enzyme that cause ZP to harden —> blocks polyspermy.

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9
Q

What happens after the cortical recitation?

A

The 2nd meiosis division (due to high Ca2+) and formation of 2nd polar body.

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10
Q

What marks the end of fertilization and start of embryonic development?

A

M and FM DNA replicates as 2 pronuclei join.

When they join, the membranes breakdown, chromosomes align at metaphase plate and first cleavage occurs.

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11
Q

1st wk occurs where?

A

Lumina of oviduct and uterus

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12
Q

16 cell morula by day:
Blastocyst:
Implantation:

A

16 cell morula by day: day 3
Blastocyst: days 4-5
Implantation: days 6-7 post ovulation

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13
Q

How are the outer cell bound?

A

By desmosomes and gap junctions = compaction

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14
Q

How is the blastocyst cavity formed?

A

Active transport of Na+ from trophos and osmosis

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15
Q

ICM is:

A

Pluripotent

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16
Q

Trophoectoderm becomes:

What is it?

A

Placenta and extra-embryonic tissues.

The outer layer of blastocyst.

17
Q

What are pinopods?
When do they appear?
What +, what -?
What is their function?

A

Projections of endometrial cells that appear between days 19 - 21 for a couple days only.
+ by progesterone, - by estrogen
In early stages of implantation, they endocytose fluids in the uterus.

18
Q

What does the blastocyst secrete to facilitate implantation?

A

Immunosuppressive agents to avoid rejection.

HCG which inhibits menstruation by keeping the CL.

19
Q

What is hCG?

A

Related to LH.
Sustains CL.
Promotes trophoblast growth and placental development.

20
Q

What are cytotrophoblasts?

A

Rapidly dividing cells that provide a feeder layer.

21
Q

Syncytiotrophoblasts do what?

A

Activates adhesion of embryo to uterine epilethia.
Causes “interstitial implantation”.
Secrete hCG at onset on implantation.
Makes tons of progesterone.
As pregnancy ensues, they have phagocytic functions, transfer wastes, nutrients, etc.

22
Q

What is hatching? What causes it?

A

Degeneration of the ZP about 6-7 days post ovulation.

Lyric factors like plasmin.

23
Q

3 stages of implantation

A

Apposition
Adhesion
Invasion

24
Q

Apposition

A

Earliest contact between ICM/trophoblasts/endometrial epithelium.
Occurs at crypts in endometrium.

25
Q

What is MUC1?

A

Transmembrane proteins on endometrium that may be involved in apposition phase.

26
Q

Adhesion

A

Microvilli of trophoblasts attach to uterine wall.
Likely ligand-receptor interactions (integrins).
Adhesion causes a dislodging of decidual cells —> further invasion

27
Q

Invasion (simple)

A

Trophoblasts contact cytotrophoblasts and syncytiotrophoblasts once blastocyst attaches.

28
Q

What do extensions of syntioitrophoblasts do during Invasion?

A

Dissociate endometrial epithelial cell by secreting TNF-a which damages the cell-to-cell adhesions.

29
Q

What do trophoblasts secrete during invasion?

A

Auto rinse factors and protease that further promote invasion.

30
Q

Metalloproteases and serine protease function

A

Degrade the ECM

31
Q

What does the blastocyst implant in within the endometrium? What is it embedded in?

A

Implants in zone compacta and is embedded in deciduas.

32
Q

Decidualization

A

Occurs in response to progesterone (which converts stromal cells).
Decidua forms junctions that do not allow movement of the implanting embryo.

33
Q

In what order does the invading syntiotrophoblasts invade the endometrial Vasculature? What does it allow for?

A

Veins first them arteries. Direct communication between between lacunae and mom’s BVs.

34
Q

Formation of primary, secondary and tertiary chorionic villi?

A

Proliferation of cytotrophoblasts —> primary chorionic villi.
Mesenchymal cells from mesoderm invade the primary CV —> secondary CV.
Eventually the mesenchymal cells form fetal BVs de novo form tertiary CV.

Endocrine And Reproduction Exam #2 (6 decks)

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