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COM: MSK (Midterm) > Lecture 7: Fertilization And Gastrulation > Flashcards

Lecture 7: Fertilization And Gastrulation Flashcards

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1
Q

During human development, which trimesters are considered embryonic and which are fetal?

A

The first trimester = embryonic

2nd and 3rd = fetal

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2
Q

What is the first step of fertilization?

A

Capacitation: glycoprotein coat and seminal plasma proteins removed from plasma membrane of sperm

  • Acrosome reaction releases: Hyaluronidase from acrosome of sperm.
  • Passage of sperm through corona radiata
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3
Q

What is the second step of fertilization?

A

Penetration of zona pellucida using estarases, acrosin and neuraminidase

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4
Q

What is the zona reaction?

A

Block to polyspermy

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5
Q

What is the third step of fertilization?

A
  • Fusion of plasma membranes of oocyte and sperm
  • Sperm bind ZP3
  • Head and tail of sperm enter oocyte and cytoplasm
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6
Q

What is the fourth step of fertilization?

A
  • Completion of second meiotic division
  • Formation of male pronucleus
  • Fusion of male and female pronuclei (46 chromosomes)
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7
Q

What are the results of fertilization

A
  • Completion of 2nd meiotic division
  • Restoration of diploid number of chromosomes
  • Determination of chromosomal sex of embryo
  • Metabolic activation of oocyte
  • Initiation of cleavage
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8
Q

What occurs during the cleavage stage of embryonic development?

A
  • Increase in cell number, decrease in cell size
  • Embryo size unchanged
  • Morula development
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9
Q

When in embryonic development does the blastocyst form?

A

Days 5-7

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10
Q

When does the late blastocyst stage occur during embryonic development and what is the significant product of this stage?

A

Week 1; inner cell mass

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11
Q

Where are embryonic stem cells derived from?

A

Inner cell mass

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12
Q

When does the trophoblast form during embryonic development and what 2 things does it give rise to?

A

Week 1

- Gives rise to the cytotrophoblast and syncytiotrophoblast

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13
Q

What is responsible for implantation and initial signal of pregnancy?

A

Syncytiotrophoblast (derived from the trophoblast) - releases hCG

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14
Q

Which derivative of the trophoblast is the stem cell layer that is mitotically active?

A

Cytotrophoblast

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15
Q

Which derivative of the trophoblast contains proteolytic enzymes and chorionic gonadotropin?

A

Syncytiotrophoblast

  • Proteolytic enzymes erode uterine lining for implantation
  • hCG is what causes morning sickness
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16
Q

What clinical presentation arises due to abnormal trophoblastic proliferation, causing excessive amounts of hCG to be produced?

A

Hydatidiform mole

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17
Q

What does the complete mole of a hydatidiform mole result from?

A

Fertilization of an empty oocyte followed by duplication of the sperm

Or

Fertilization of an empty oocyte by 2 spermatocytes

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18
Q

What does a partial mole of a hydatidiform mole result from?

A

Fertilization of a normal oocyte by 2 sperm

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19
Q

What are the clinical features of a hydatifiiform mole?

A
  • Vaginal bleeding
  • Pelvic pressure or pain
  • Enlarged uterus
  • Hyperemesis gravidarum
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20
Q

What are choriocarcinomas?

A

Malignant tumors which develop from hydatidiform moles (rare)

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21
Q

What does the inner cell mass divide into?

A

The epiblast (intraembryonic) and hypoblast (extraembryonic)

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22
Q

What are the derivatives of the epiblast?

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A

Ectoderm
Amnion
Amniotic cavity
Intraembryonic structures

23
Q

What are the derivatives of the hypoblast

Study These Flashcards
A

Endoderm -> prechordal plate, primary and secondaary yolk sac, and extraembryonic mesoderm
Extraembryonic structures -> just a place holder during week 2 then degenerates

24
Q

What is the extraembryonic coelom?

Study These Flashcards
A

Hollow cavity outside of the embryo

25
What is the extraembryonic somatic mesoderm?
Linking of the trophoblast and covering of the amnion
26
What is the extraembryonic splanchnic mesoderm?
Lines the yolk sac
27
What are the 3 derivatives of extraembryonic mesoderm?
Connecting stalk Primitive blood Chorion
28
What type of extraembryonic mesoderm is the connecting stalk derived from?
Extraembryonic somatic mesoderm
29
What type of extraembryonic mesoderm is primitive blood derived from?
Extraembryonic splanchnic mesoderm
30
What type of extraembryonic mesoderm is the chorion derived from?
Extraembryonic somatic mesoderm
31
When during embryonic development does the inner cell mass form?
Week 1
32
When during embryonic development does the epiblast and hypoblast form
Week 2
33
When during embryonic development does gastrulation occur?
Week 3
34
What does vaginal bleeding beyond 20 weeks gestation indicate?
Placenta Previn - Antepartum bleeding should prompt sonography can evaluation BEFORE digital vaginal examination -> palpating of the placenta can cause severe hemorrhage
35
What 3 things make up the primitive streak?
Primitive knot Primitive groove Primitive pit
36
_______________ are rare slow growing aggressive neoplasms of bone
Chordomas
37
What do chordomas arise from?
Remnants of notochord
38
Where do chordomas occur?
In axial skeleton in spheno-occipital region of skull and sacral regions
39
What are the 3 types of mesoderm?
Paraxial Inermediate Lateral
40
What does lateral plate mesoderm give rise to?
CT -> Blood, lymph, mesenteries, cardiovascular
41
How long does fertilization last and where is this occurring?
About 24 hours and occurs in the distal 1/3 of the Fallopian tube, called the Ampulla.
42
Importance of prechordal plate and cloacal membrane having only an endodermal and ectodermal component?
Having no mesoderm or blood supply, they will eventually die/disintegrate and this is good so that we are able to ingest food through the mouth and expel waste from the anus
43
What structures will arise from the ectoderm, mesorderm, and endoderm?
Ectoderm - skin, hair, nails, brain, and spinal cord Mesoderm - heart, blood, bone, and muscle Endoderm - GI, liver, lungs, glands, bladder
44
Function of neural plate and what induces its formation?
- Provides a template for cells to migrate and become the vertebral column. - Induced by Sonic Hedgehog (Shh)
45
Somatopleure takes the _____layer of the lateral plate and ______? Forms?
- Somatic layer of the lateral plate (mesoderm) and the ectoderm. - Forms the body wall
46
Splanchnopleure takes the ______layer of the lateral plate and ______? Forms?
- Splanchnic layer of the lateral plate (mesoderm) and the endoderm. - Forms the circulatory system.
47
Cells forming the notochord migrate from the ______ in a _______ direction. Between the endoderm and ectoderm they form a tube called the ________?
Migrate from the primitive pit in a cephalic direction. Form a tube called the notochordal process.
48
At the time the notochordal plate is forming which two strucutres are in communication?
The amniotic cavity and the primary yolk sac.
49
When does the morula enter the uterus?
Day 4
50
When does the morula develop during cleavage?
Day 3
51
When does the zona pellucid degenerate?
Day 5
52
What does the trophoblast give rise to?
Placenta
53
What cell type secretes human chorionic gonadotropin to maintain pregnancy?
Syncytiotrophoblasts
54
When is the cloacal membrane formed?
Prior to the formation of the primitive streak

COM: MSK (Midterm) (23 decks)

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