Embryology Flashcards

1
Q

What occurs within the first week of embryology

A

Ovulation
Fertilisation
Implantation

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2
Q

Roughly when does implantation occur

A

5 1/2 - 6 days

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3
Q

What is a zygote

A

A fertilised ovum

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4
Q

What is a morula

A

A mass of cells resulting from division or a fertilised ovum

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5
Q

What is a blastocyst

A

A hollow ball of cells:
-Inner cell mass
-Trophoblast

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6
Q

What is the purpose of the placenta

A

A way to transfer nutrients and waste to and from the mother

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7
Q

When might a baby and mother’s circulatory system interact

A

During birth

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8
Q

Is the placental barrier permeable

A

Yes to most molecules but not cells

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9
Q

What is an embryological difference between identical and fraternal twins after implantation

A

Fraternal twins each have a placenta while identical twins share a placenta

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10
Q

When does the implanted trophoblast contain a bilaminar embryo

A

10-12 days

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11
Q

What layers does the bilaminar embryo have

A

Epiblast layer
Hypoblast layer

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12
Q

What does the epiblast layer give rise to

A

Embryonic ectoderm
Mesoderm
Endoderm
Mesendoderm?

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13
Q

What does the hypoblast layer participate in

A

Formation of endoderm and extraembryonic mesoderm

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14
Q

What does the embryo develop during gastrulation

A

An axis (becomes bilaterally symmetrical)
The three embrionic cell layers

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15
Q

What is the key stage of gastrulation

A

Formation of a groove, the primitive streak

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16
Q

What does organogenesis mean

A

Generating an organ

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17
Q

What forms the mesoderm

A

Ectodermal cells induced to differentiate and migrate through the primitive streak towards the hypoblast

18
Q

What forms the third layer to form the trilaminar embryo

A

The mesodermal cells push through the primitive streak and spread out to form a third layer

19
Q

What is one of the first organs to be formed

A

Central nervous system

20
Q

What is developing muscle called

A

Somite

21
Q

When is the neural groove evident

A

19,20 days when the embryo is about 2mm long

22
Q

What is the order of development of the central nervous system

A

Neural fold
Neural groove
Neural tube
Dorsal root ganglion

23
Q

What defects are associated with the neural groove

A

Spina bifida -non closer of neural groove lack of formation of the neural tube

24
Q

When do the cells become a foetus

A

Week 9 as there is development of organs

25
Q

Why is the neural crest also known as ‘ectomesenchyme’

A

Derived from ectoderm but has the characteristics of mesenchyme

26
Q

Approx how long is the embryo at 7 weeks

A

27mm

27
Q

What length is the fetus at weeks 9,14,20

A

44mm
120mm
185mm

28
Q

Where do all body cells originate from

A

3 cell types:
-Ectoderm: outer covering
-Mesoderm: middle
-Endoderm: inner lining

29
Q

When does the face start to form

A

Week 4-7 via migration of cells from posterior to anterior region

30
Q

Which stem cells are totipotent

A

Embryonic inner cell mass - capable of giving rise to any cell type

31
Q

Which embryonic stem cells are pluripotent

A

Cells in the 3 germ layers

32
Q

What does stem cell development involve

A

Genes and various signalling molecules

33
Q

What does the ectoderm compose

A

Skin
TOOTH ENAMEL
Mucous membranes of mouth,anus
Brain, spinal chord

34
Q

What structures are made of mesoderm

A

Most connective tissues
-Dermis, tendons, cartilage, bone
Muscle (most)
Blood vessels
Kidney and urinary system
Reproductive system
Serous membranes

35
Q

What does the endoderm make up

A

Alimentary canal (pharynx - rectum)
Respiratory system
Parts of urogenitakl system

36
Q

What is the ‘fourth’ primary embryonic layer

A

Ectomesenchyme

37
Q

What does the ectomesenchyme give rise to

A

Most of the peripheral nervous system: sensory + autonomic
Melanocytes
Adrenal medulla
Most of the mesenchyme in the head
Dentine, cementum, pulp, periodontal ligament, jaw bones

38
Q

When is the period of greatest sensitivity for development in utero

A

First trimester: weeks 3-12

39
Q

When do teeth begin to form in utero

A

week 6-7

40
Q

When are primary teeth fully formed

A

Around week 9