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Block A - Molecules to Global Health > Embryology > Flashcards

Embryology Flashcards

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Organic Chemistry 101 flashcards
1
Q

Define phases of development

A
  1. Embryonic phase (60 days): formation of cells, tissues and organs –> vulnerable phase
  2. Foetal development
  3. Neonate (1 month)
  4. Infant (1 year)
  5. Child
  6. Puberty
  7. Adolescence
  8. Adult
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2
Q

List the 5 significant mechanisms of development

A
  1. Mitosis
  2. Cellular interactions
  3. Cell and tissue migration
  4. EMT-MET
  5. Apoptosis
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3
Q

What happens in the pre-implantation phase (days 1-6)

A

Develops in the fallopian tube to form a TOTIPOTENT ZYGOTE to a blastocyst, in the zona pellucida. It is an independent growth where there is apoptosis to remove chromosome defects. If not fertilized in 24-48h, it degenerates. Steps:

  1. the secondary oocyte is inhibited at secondary meiotic division.
  2. Sperm binding to ZP3 receptor and release acrosin to enter the oocyte. Once it’s there, there’s : (1) prevention of polyspermy by depolarization of membrane and (CA 2+) and (2) completion of the meiosis II
  3. DNA synthesis in pronuclei: the two pronucleus (male and female) will move toward each other and form a single spindle = SYNGAMY
  4. Zygote undergoes mitosis and there is continued equal division of cytoplasm = formation of blastomere up to 16
  5. Compaction phase: the outer and inner microenvironments establish, development of gap junctions and basement membrane. INSIDE-OUT HYPOTHESIS
  6. Blastocyst formation: trophectroderm (forms placenta) + inner cell mass (ICM, forms embryo) = CONCEPTUS
  7. Then the primitive endoderm is formed. We now have the first three lineages and they undergo rapid conceptus changes
  8. An amniotic cavity is formed in the ICM as the endoderm lines the trophoblast to form yolk sac. We now have a bilaminar embryo (primitive ectoderm and primitive endoderm), the amniotic epithelium and the yolk sac
  9. Newly-formed extra-embryonic mesenchyme separates from trophoblast layer from bilaminar embryo, yolk sac and amniotic cavity
  10. extra-embryonic coelum form super fast and formation of connecting stalk : The bilaminar embryo seen with newly formed mesenchyme associates with the placental tissue and will form blood and vessels
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4
Q

What happens in the implantation phase (days 6-10)

A

IMPLANTATION IS AN ACTIVE INVASION OF THE ENDOMETRIUM BY THIS CYTOTROPHOBLAST FORMING SYNCYTIO-TROPHOBLAST AND GOING INSIDE THE ENDOMETRIUM

  1. Cytotrophoblasts and syncyto-trophoblast derived from trophoblast
  2. Lacunae with maternal blood (the syncyto, as it erodes, will break down the mama blood vessels)
  3. Utero-placental circulation established: pregnancy initiated by hormonal maintenance of glandular endometrium = initiation of pregnancy
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5
Q

What happens in the post-implantation phase (implantation until birth)

A

Bilaminar embryo and becomes trilaminar embryo trough gastrulation.
Gastrulation: formation of 3 embryonic germ cell layers (primitive ectoderm, primitive mesoderm and definite endoderm)
1. Primitive node and streak represents sites of active gastrulation
2. Primitive streak reduit as new mesenchyme cells migrate cranially
3. As the primitive streak recedes, the cranial region elongates
4. Induction of primitive ectoderm to form the neural plate (neurectoderm)

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6
Q

gestational period

A

from fertilization to birth (also called prenatal period)

- include embryonic phase (- 60 days) and fetal phase (60-266 days)

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7
Q

different phase of postnatal development

A

neonate, infant, childhood, puberty, adolescence, adulthood

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8
Q

histogenesis

A

organisation of cells into functionnal tissues

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9
Q

organogenesis

A

interactions between tissues to from an organised functionnal organ

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10
Q

fetal development

A

phase in which active differentiation and formation of organs and system progress in preparation for birth

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11
Q

ontogeny

A

study of the continuous changes from fertilization to death

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12
Q

During migration of single cell, there’s 3 categories of single cells that are gonna migrate for distances in embryo. What are they ?

A
  1. neural crest cells
  2. primordial germ cells
  3. hemopoietic cells
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13
Q

what are neural crest cells ?

A

pluripotent cells from margins of central nervous system to body target tissue

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14
Q

what are primordial germ cells

A

primitive ectoderm to yolk sac. It forms early than migrated away from the embryo and it’s gonna come back to form the gonads

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15
Q

what are hemopoietic stem cells

A

migrate into intra and extra-embryonic mesenchyme (yolk sac and other extra and intra-embryonic/placental sites)

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16
Q

on what is dependant tissue migration ?

A 
PCP genes (planar cell polarity genes) that confers polarity on individual cells within an epithelium and also initiates oriented movements of groups of cells within tissue 
- no PCP = no polarity = genetic defects
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17
Q

what is conversion-extension (CE) ?

A

oriented movements of groups of cells within tissue to end polarized and in lines

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18
Q

gap junctions

A

proliferating cells form an aggregation of cells and communicate via gap junctions (they can influence whole populations of cells, signaling all the cells to form certains numbers of proliferation and stop). GAP JUNCTION KEEP THIS CRITICAL CELL MASS (IMPORTANT)

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19
Q

how is the transition between EMT-MET

A

HOW EPITHELIUM BECOMES MESENCHYME

  1. loss of apico-basal polarity
  2. breakdown of adhesion devices and cytoskeletal reorganisation (BM starting to breakdown)
  3. the middle cell can now migrate outside of the cell structure , out to the B, that becomes the mesenchymal cells
20
Q

does apoptosis occur during pre or post-natal development ?

A

BOTH

  • pre : facilitates sculpturing/shaping of organs
  • post : maintains optimal cell numbers in renewing tissues
21
Q

goal of the pre-implantation development ?

A

zygote is going to form the embryo before it implants in the uterus. Develops within the Fallopian tube to form a blastocyst (INDEPENDANT DEVELOPMENT)

22
Q

what are the 3 prenatal phases of development ?

A
  1. pre-implantation phase (1-6 days)
  2. implantation phase (day 6-10)
  3. post-implantation phase (day 10 - birth)
23
Q

goal of the implantation phase ?

A

active embedding/erosion into the endometrium and establishment of early placenta to become dependant of the mother’s blood for nutrition

24
Q

goal of the post-implantation phase ?

A

fully dependant on the mother’s blood for nutrition, excretion and gazeous exchange

25
Q

totipotency

A

potential for a cell to form a conceptus (embryo + placenta)

26
Q

conceptus

A

embryo + placenta

27
Q

pluripotency

A

potential to form multiple cell lineages

28
Q

2 main roles of zona pellucida

A
  1. have a receptor ZP3 that’s gonna combine with the sperm

2. maintaning independance of the secondary oocyte as it divides

29
Q

syngamy

A

male and female chromosome combine all the spindle in the metaphase

30
Q

what happens to the totipotency as the number of blastomeres increase ?

A

it’s reduced (16 = super low)

31
Q

what happens if, during your development, the inner cells mass separates into 2 littles ICMs ?

A

you will have 2 identical embryo within one placenta.

- if separation isn’t complete, you have conjoint twins

32
Q

what will the trophectoderm/trophoblast form ?

A

placenta

33
Q

what will the ICM form ?

A

embryo

34
Q

what are the first 3 lineages ?

A
  1. an outer trophectoderm
  2. a pluripotent inner cell mass (ICM)
  3. a primitive endoderm
35
Q

what’s the connecting stalk ?

A

made of extra-embryonnic mesenchyme, it connects the embryo to the trophoblast and will be the core of the ombilical cord

36
Q

what does the extra-embryonnic mesencgyme contain ?

A
  1. primordial germ cells (PGCs)

2. Hemangioblasts (precursor of blood vessels)

37
Q

what are the two layers of the trophoblast that develop during implantation?

A

cyto-trophoblast (more inside) and syncytio-trophoblast (more outside)

38
Q

how can you detect pregnancy early ?

A

the first hormone that the syncytiotrophoblast produce is called GONADOTROPHIN that will go to the mother’s blood.

39
Q

how is the next menstruation is évité when you are pregnant ?

A

gonadotrophin once in the blood will reach the ovaries and cause that ovarian structure to produce estrogen and progesterone and that will maintain the endometrium for pregnancy

40
Q

which structures designate dorsal/ventral ?

A
  • DORSAL : primitive ectoderm

- VENTRAL : primitive endoderm

41
Q

which structures designate midline and symmetry ?

A
  • where the notochord and precordal plate is
42
Q

which structures designate cranial - caudal ?

A
  • CRANIAL = precordal plate and buccopharyngeal membrane

- CAUDAL - cloacal membrane

43
Q

neural crest cells ?

A

when the primitive streak is going to be reduce in size as the primitive node increases in lenght, the margin between the surface ectoderm and the neural plate is a layer of cells called the neural crest (pluripotent cells that can form any cells layers)

44
Q

what each of the lineage will form ?

A
  1. ECTODERM : neural crest, CNS, skin epithelium and glands
  2. MESODERM : connective tissues, cartillage, cardiovasculatoir system, cavities
  3. ENDODERM : lining of GI system and gland and lining of epithelium in respiratory system
45
Q

Sacrococcygeal teratoma

A

form by ectopic stem cell that hasn’t migrated. If you make histological sections of this terratoma, it’s possible to see every possible tissue of the body (because the original cells are pluripotent)

Block A - Molecules to Global Health (8 decks)

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