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Medicine yr1 > FOUND-SOM-embryology > Flashcards

FOUND-SOM-embryology Flashcards

1
Q

what event occurs on week 1 day 1?

A

fertilisation

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2
Q

what events occurs on week one day 3?

A

morula (16 cell embryo)

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3
Q

what event occurs on week 1 day 4?

A

blastocyst formation/ entrance into uterine cavity

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4
Q

what event occur week 1 day 5?

A

embryo attaches to uterine wall beginning implantation

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5
Q

when does the differentiation of trophoblast into cytotrophoblast and syncyttiotrophoblast take place?

A

week 1-2

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6
Q

what week does the embryo complete implantation?

A

week 2

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7
Q

which days does the formation of the bilaminar disk occur?

A

days 7/8

week 2

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8
Q

when does gastrulation (formation of trilaminar disk) occur?

A

week 3

days 13-17

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9
Q

when does neurulation occur?

A

week 3 (finished by end of week)

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10
Q

what 2 events occur during week 4?

A
  • primordial heart starts pumping blood

- limb buds appear

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11
Q

which 2 events occur during week 6?

A
  • embryo shows spontaneous movement

- embryo heart can be seen with ultrasound

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12
Q

what is capacitation and when does it occur?

A
  • a conditioning process sperm undergoes 7hrs before fertilisation
  • involves removal of cholesterol, glycoproteins and proteins from plasma membrane around acrosomal region of sperm
  • sperm penetrates corona radiata
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13
Q

describe the acrosome reaction?

A
  • occurs as sperm approaches zona pellucida ( around ovum)
  • enzyme acrosin is released to perforate ZP and digest proteoglycan which make up ZP
  • plasma mem of sperm and ovum fuse so sperm’s genetic info is released into ovum
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14
Q

what remaines outside the ovum during the fusion of ovum and sperm?

A

mitochondria of sperm and everything else of sperm remains outside of ovum

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15
Q

describe the cortical reaction.

A
  • cortical granules undergo exocytosis due to release of Ca2+ and granules further digest ZP
  • ZP hardens
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16
Q

what does the cortical reaction prevent?

A

polyspermy

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17
Q

Where does fertilisation usually occur?

A

in ampulla of fallopian tube

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18
Q

what happens in fertilisation?

A
  • secondary oocyte completes 2nd meiotic division

- haploid sperm + haploid secondary oocyte merge into single diploid nucleus (zygote)

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19
Q

how does the zygote cleave into morula?

A
  • cleavage=rapid mitotic cell division of zygote creating individual blastomeres
  • after 72hrs of repeated division-cluster of 16 called a morula
  • ZP remains intact-does not increase in size
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20
Q

what is a blastocyst?

A

once the cell reaches 32-cell stage

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21
Q

what does the blastocyst reorganise into?

A
  • trophoblast-outer layer, will develop into large part of the placenta
  • embryoblast-inner cell mass, develop into embryo
  • blastocoele-fluid filed compartment. forms the primitive yolk sac. created in the process captivation as the trophoblasts secrete fluid into the morula forming the blastocoele on day 5
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22
Q

what day does the Zona pellucida begin to disintegrate and what is this process called?

A

day 5

embryo hatching

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23
Q

what events occur during implantation?

A
  • blastocyst attaches to endometrial epithelium wall
  • trophoblast will adhere and secrete digestive enzymes and growth factors against endometrial surface
  • trophoblast proliferates and gives rise to 2 layers
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24
Q

which 2 layers does the trophoblast give rise to during implantation?

A

1-cytotrophoblast-inner layer-forms villi

2-syncytiotrophoblast-outer layer that erodes maternal tissues

  • secreted hCG
  • maternal blood flows into lacunae form by syncytiotrophoblasts
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25
Q

which day does the embryo differentiate into hypoblast and epiblast and what does it form?

A

day 8

forms Bi-laminar disc

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26
Q

what does the blastocoel develop into and when?

A

yolk sac

day 9-10

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27
Q

where is the bi-laminar disc positioned?

A

between amniotic cavity and yolk sac

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28
Q

what is the process of gastrulation?

A

process where bi-laminar disc become tri-laminar disc with 3 germ layers

days 13-17

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29
Q

how is the primitive streak formed?

A

epiblasts begin to migrate inward (invaginate) forming a primitive streak

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30
Q

what are the tri-laminar layers and which bi-laminar layers do they form from?

(3 germ layers)

A
  • cells replacing the hypoblast form the—–> embryonic endoderm
  • cells between the epiblast and endoderm (former hypoblasts) form the —>embryonic mesoderm
  • cells remaining in the epiblast form the embryonic ectoderm
31
Q

what are the germ layer derivatives of the ectoderm?

A
  • skin
  • nails
  • hair
  • CNS (brain and spinal cord)
32
Q

what are the germ layer derivatives of the mesoderm?

A
  • musculoskeletal system
  • cardiovascular system
  • excretory system
  • reproductive system
33
Q

what are the 7 germ layer derivatives of the endoderm?

A
  • GI tract
  • lungs
  • liver
  • pancreas
  • bladder
  • thyroid/ parathyroid glands
  • thymus
34
Q

describe the formation of notochordal process.

A

-mesodermal cells from primitive node migrate toward the rostral end (head end) of the embryo and form a hollow tube of cells in the midline-notochordal process

35
Q

how is the notochord formed?

A

the notochordal process cells will proliferate and detach from the endoderm to from a solid chord of cells-notochord

36
Q

what does the paraxial mesoderm differentiate into?

A

skeleton and muscles

37
Q

what does the intermediate mesoderm differentiate into?

A

gonads and kidneys

38
Q

what does the lateral plate mesoderm differentiate into?

A

heart and blood vessels

39
Q

what does the extraembryonic mesoderm differentiate into?

A

chorion

40
Q

what does the neural tube give rise to?

A

CNS

41
Q

what is neurulation?

A

neural tube formation

42
Q

what is the first step of neurulation?

A

1- neuroectoderm tissues differentiate from ectoderm an thicken into neural plate
-neural plate border separates the ectoderm from the neural plate

43
Q

how is the neural crest formed in the second step of neurulation?

A

2-the neural plate bends dorsally, with 2 ends eventually joining at the neural plate borders which are now referred to as the neural crest

44
Q

what is the 3rd step of neurulation?

A

3-the closure of the neural tube disconnects the neural crest from the epidermis
-neural crest cells differentiate to form most of the peripheral nervous system

45
Q

what happens to the notochord and mesoderm in the final step of neurulation and what do they form?

A

4-the notochord degenerates and only persists as the nucleus pulposus of the intervertebral discs

-other mesoderm cells differentiate into the somites, precursors of the axial skeleton and skeletal muscle

46
Q

where are the pharyngeal arches formed?

A

within cranial region due to growth of mesenchymal tissue

47
Q

what are pharyngeal arches separated by?

A

pharyngeal clefts

48
Q

how many pharyngeal arches are there?

A

6

however the 5th regresses soon after froming

49
Q

what are the 2 types of pharyngeal arch 1 and what cranial nerve are they innervated by?

A
  • maxillary
  • mandibular

-trigeminal nerve (V)

50
Q

what are the muscle derivatives of the PA1 (maxillary)?

A
  • superior oblique
  • abducens
  • oculomotor muscles
51
Q

what are the muscle derivatives of the PA1 (mandibular)?

A
  • muscles of mastication
  • tensor tympanis
  • digastric (anterior abdomen)
52
Q

what are the muscles derivatives of PA2 (hyoid)?

A
  • muscles of facial expression
  • digastric (posterior abdomen)
  • styloid
53
Q

which cranial nerve is PA2 innervated by?

A

facial nerve

54
Q

which cranial nerve is PA3 innervated by?

A

glossopharyngeal nerve

55
Q

which cranial nerve are PA4 and PA6 innervated by?

A

laryngeal branches of vagus nerve

56
Q

what are the muscle derivatives of PA3?

A

Stylopharyngeas

57
Q

what are the muscle derivatives of PA4 and PA6?

A

striated muscles of oesophagus

58
Q

what are the skeletal derivatives of PA1? (maxillary)

A

maxillary, palatine, jugal

trabecular cranii

59
Q

what are the skeletal derivatives of PA1 (mandibular)?

A

incus. ant. lig. of malleus
palatoquadrate
meckel’s cartilage

60
Q

what are the skeletal derivatives of PA2?

A

stapes
hyoid bone
reichert’s cartilage

61
Q

what are the skeletal derivatives of PA3?

A

horns of hyoid

thyroid cartilage

62
Q

what are the skeletal derivatives of PA4 and PA6?

A

cricoid cartilage

63
Q

which germ layer gives rise to the lining of the digestive tract?

A

endoderm

64
Q

on what day does implantation occur?

A

day 6

65
Q

which 2 processes must occur before fertilisation can happen?

A
  • capacitation of sperm

- acrosome reaction of sperm

66
Q

what is the zona pellucida?

A

-expresses specific receptor proteins which bind to proteins expressed in heads of spermatozoa-triggers acrosome reaction

67
Q

what does the formation of the primitive streak in gastrulation do?

A

defines the body axis of the embryo

  • cranial end (head)/ caudal end (tail)
  • left/ right
68
Q

at which end does the neural plate of thickened cells form in neurulation and which way does it grow?

A
  • forms at cranial end

- grow in cranial to caudal direction

69
Q

what occurs as a result of embryo folding?

A

major body plan is established as the 3 germ layers continue to differentiate

70
Q

what is embryonic folding in 2 planes simultaneously a result of?

A

differing rates of growth of the embryonic structures

71
Q

what are 3 parts the gut tube is divided into?

A
  • foregut
  • midgut
  • hindgut
72
Q

give a summary of the events that occur in week 2 of development

A
  • implantation of blastocyst is completed
  • bilaminar embryonic disc is formed-composed of hypoblast and epiblast
  • a number of extraembryonic structures also formed
73
Q

give examples of the extraembryonic structures formed during the 2nd week of development

A
  • amniotic cavity
  • aminon
  • umbilical vesicle (yolk sac)
  • connecting stalk
  • chorion sac

Medicine yr1 (55 decks)

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