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

Lecture 7: Fertilization And Gastrulation Flashcards

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?

A

Ectoderm
Amnion
Amniotic cavity
Intraembryonic structures

23
Q

What are the derivatives of the hypoblast

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?

A

Hollow cavity outside of the embryo

25
Q

What is the extraembryonic somatic mesoderm?

A

Linking of the trophoblast and covering of the amnion

26
Q

What is the extraembryonic splanchnic mesoderm?

A

Lines the yolk sac

27
Q

What are the 3 derivatives of extraembryonic mesoderm?

A

Connecting stalk
Primitive blood
Chorion

28
Q

What type of extraembryonic mesoderm is the connecting stalk derived from?

A

Extraembryonic somatic mesoderm

29
Q

What type of extraembryonic mesoderm is primitive blood derived from?

A

Extraembryonic splanchnic mesoderm

30
Q

What type of extraembryonic mesoderm is the chorion derived from?

A

Extraembryonic somatic mesoderm

31
Q

When during embryonic development does the inner cell mass form?

A

Week 1

32
Q

When during embryonic development does the epiblast and hypoblast form

A

Week 2

33
Q

When during embryonic development does gastrulation occur?

A

Week 3

34
Q

What does vaginal bleeding beyond 20 weeks gestation indicate?

A

Placenta Previn

  • Antepartum bleeding should prompt sonography can evaluation BEFORE digital vaginal examination -> palpating of the placenta can cause severe hemorrhage
35
Q

What 3 things make up the primitive streak?

A

Primitive knot
Primitive groove
Primitive pit

36
Q

_______________ are rare slow growing aggressive neoplasms of bone

A

Chordomas

37
Q

What do chordomas arise from?

A

Remnants of notochord

38
Q

Where do chordomas occur?

A

In axial skeleton in spheno-occipital region of skull and sacral regions

39
Q

What are the 3 types of mesoderm?

A

Paraxial
Inermediate
Lateral

40
Q

What does lateral plate mesoderm give rise to?

A

CT -> Blood, lymph, mesenteries, cardiovascular

41
Q

How long does fertilization last and where is this occurring?

A

About 24 hours and occurs in the distal 1/3 of the Fallopian tube, called the Ampulla.

42
Q

Importance of prechordal plate and cloacal membrane having only an endodermal and ectodermal component?

A

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
Q

What structures will arise from the ectoderm, mesorderm, and endoderm?

A

Ectoderm - skin, hair, nails, brain, and spinal cord
Mesoderm - heart, blood, bone, and muscle
Endoderm - GI, liver, lungs, glands, bladder

44
Q

Function of neural plate and what induces its formation?

A
  • Provides a template for cells to migrate and become the vertebral column.
  • Induced by Sonic Hedgehog (Shh)
45
Q

Somatopleure takes the _____layer of the lateral plate and ______? Forms?

A
  • Somatic layer of the lateral plate (mesoderm) and the ectoderm.
  • Forms the body wall
46
Q

Splanchnopleure takes the ______layer of the lateral plate and ______? Forms?

A
  • Splanchnic layer of the lateral plate (mesoderm) and the endoderm.
  • Forms the circulatory system.
47
Q

Cells forming the notochord migrate from the ______ in a _______ direction. Between the endoderm and ectoderm they form a tube called the ________?

A

Migrate from the primitive pit in a cephalic direction. Form a tube called the notochordal process.

48
Q

At the time the notochordal plate is forming which two strucutres are in communication?

A

The amniotic cavity and the primary yolk sac.

49
Q

When does the morula enter the uterus?

A

Day 4

50
Q

When does the morula develop during cleavage?

A

Day 3

51
Q

When does the zona pellucid degenerate?

A

Day 5

52
Q

What does the trophoblast give rise to?

A

Placenta

53
Q

What cell type secretes human chorionic gonadotropin to maintain pregnancy?

A

Syncytiotrophoblasts

54
Q

When is the cloacal membrane formed?

A

Prior to the formation of the primitive streak

COM: MSK (Midterm) COPY (23 decks)

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