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IMS 1 > S5- Embryology > Flashcards

S5- Embryology Flashcards

1
Q

2 causes of human birth defects:

A

Genetic= monogenic mutations/ chromosomal mutations (numeral/ aneuploidy or structural)

Environmental= teratogens

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2
Q

5 types of teratogens:

A
  1. Infectious (TORCH)= 5 examples
  2. Chemical= thalidomide and alcohol
  3. Physical= radiation
  4. Maternal disease= diabetes
  5. Deficiency= folic acid
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3
Q

Highest Risk of birth defects in embryonic period is around…

A

5 weeks

(3-8 weeks)

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4
Q

Infectious teratogens can…

A

Cross the placenta and cause birth defects

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5
Q

Folic acid deficiency (vitamin B) causes malformations in…
OTC supplements…risk by…

2 congenital malformations are:

A

Central nervous formations
Reduce, 60%

  1. Spina bifida (gaps in spinal cord/ doesn’t develop fully)
  2. Anencephaly (born without parts of brain or skull)
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6
Q

Diabetes can cause…

4 congenital malformations:

A

Cellular structural defects and changes in cellular physiology

  1. Macrosomia (larger than average0
  2. Ventricular septal defect
  3. Spina bifida
  4. Renal agenesis
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7
Q

Trophoblasts are the….cells of zygote and they differentiate into…

A

outside
Cytotrophoblasts and syncytiotrophoblasts (membranes break down/ have no defined membranes)

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8
Q

Embryoblasts are…and they differentiate into…

A

Cells in the middle
Hypoblast and epiblast

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9
Q

the terminology used to describe an embryo

A

Cranial= head region
caudal= tail region
ventral= front
dorsal= back

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10
Q

the planes used to describe an embryo

A

transverse= cutting across waste
sagittal= cutting through midline
coronal= divide into ventral and dorsal

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11
Q

the 2 techniques used to date a pregnancy

A
  1. menstrual age (clinicians)= from last mentrual cycle (1st day of bleeding) + 3 equal trimesters
  2. Fertilisation age (embryologists)= more specific + 3 unequal trimesters
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12
Q

the 3 trimesters of fertalisation age

A
  1. early development (includes cell division + pre-embryonic) 0-3 weeks
  2. Embryonic + organ development (organogenesis) 3-8 weeks
  3. foetal period 8-38 weeks
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13
Q

radiation can cause…and make the CNS more…
it is most sensitive in…trimester
3 congenital malformations are:

A

cell death or chromosomal changes
Sensitive
First
1. Microcephaly
2. mental and congnitive disabilities
3. haemopoietic malignancies (cancers in blood-forming tissues such as bone marrow) and leukemia (cancers of the blood)

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14
Q

two chemical teratogens

A
  1. thalidomide= prescribed for morning sickness and causes shortened or absent limbs (now used to treat leprosy and HIV)
  2. foetal alcohol syndrome= prenantal and postnatal growth retardation (doesnt grow at normal rate), intellectual disability, impaired motor ability and coordination
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15
Q

TORCH infectious teratogens and zika virus

A

1.toxoplasmosis= parasite in cat faeces and undercooked/ raw meat= asymptomatic
2. Other (hipatitis B, syphilis)
3. rubella (german measles)= rubella virus, use MMR vaccine= rash
4. cytomegalovirus (CMV)= via bodily fluids= asymptomatic
5. Herpes simplex virus (HSV)= varicella zoster virus- chickenpox
6. zika virus= mosquito, bodily fluids, fever/rash/ red eyes/ joint pain

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16
Q

outline the steps in the hormone cycle

A
  1. hypothalamus= GnRH (gonadotropin releasing hormone)
  2. stimulates gonadotropes in pituitary gland to release FSH and LH
  3. FSH and LH stimulate follicular phase and production of oestrogen
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17
Q

names of cells and follicles as they develop in hormone cycle

A
  1. oogonia (diploid 2n cell)
  2. primordial follicle (2n)= frozen in prophase 1
  3. primary follicle (2n)
  4. early secondary follicle (2n)
  5. late secondary follicle (2n)
  6. graafian follicle (n)- frozen in metaphase 2- contains antrum
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18
Q

once oestrogen reaches a critical level as oocytes mature in ovary, oestrogen exerts….feedback on…

follicle notices rise in oestrogen= produce…to inhibit pituitary from producing FSH
this results in…

A

Positive
hypothalamus= more GnRH= more FSH and LH
inhibin B
LH surge

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19
Q

the rule of LH in ovulation

ovulation occurs around day…

A
  1. increase blood flow and permeability into second half of follicle (blood vessels local to antrum)= more follicular fluid in antrum
  2. activate proteases enzymes that cleave tissue around graafian follicle= oocyte erupts from graafian follicle (ovulation)
  3. stimulate the remaider of graafian follicle into hormone factory= corpus luteum (produce progesterone)

14-15

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20
Q

if no fertalisation occurs, the corpus luteum….approx…days after…and oestrogen and progesterone…

if fertalisation occurs then cells called…secrete…to stimulate secretion of hormones until….takes over

A

degrades
10 days
Ovulation
Decrease

syncytiotrophoblasts
hCG
an implanted placenta

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21
Q

the outline/ steps of fertalisation/ week one after ovulation:

A
  1. capacitation of sperm (cleaning up head of sperm= removal of proteins and increase motility) -> pass through corona radiate
  2. acrosome reaction= releases enzymes to penetrate zona pellucida
  3. cortical reaction= impermeable zona pellucida
  4. cleavage= proliferation
  5. formation of morula= 16-32 cells (inner mass and outer mass)
  6. blastulation= morula-> blastocyte (fluid-filled cavity and emryoblasts and trophoblasts)
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22
Q

after sperm joins egg, a….forms and after fusion of….a…forms

A

zygote
pronuclei
embryo

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23
Q

The…sweep the oocyte into the uterine tube/ fallopian tube and fertalisation takes place at the….

A

fimbriae
ampulla

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24
Q

significance of the bilaminar disc

A

establish dorsal/ ventral axis of embryo
epiblast= dorsal/ back
hypoblast= ventral/ front

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25
Q

the small fluid filled ceviity forms in the epiblast layer to form the bilaminar disc is called…

A

amniotic cavity

26
Q

to establish uteroplacental circulation, syncytiotrophoblasts….

A

erode walls of maternal capillaries

27
Q

outline of week 2 (implantation)

A
  1. Amniotic cavity forms in epiblast layer (day 8)
  2. migration of hypoblast to encase blastocyte cavity (important fo yolk sac to form) (day 9)
  3. uteroplacental circulation + primary yolk sac (day 10-11)
  4. new layer of connective tissue forms from yolk sac and cytotrophoblast = extraembryonic mesoderm (10-12)
  5. chorionic cavity forms in extraembryonic mesoderm (12-13)
  6. Hypoblasts migrate again= form secondary yolk sac
  7. end of week 2= amniotic cavity+ secondary yolk sac suspended in chorionic cavity by CONNECTING STALK
28
Q

the cells….secrete hormone….that is used in pregnancy testing
it makes corpus luteum continue to secrete…

A

syncytiotrophoblasts
hCG= human chorionic gonadotrophin (and may play a role in maternal immunotolerance)
progesterone (to maintain endometrium)

29
Q

abnormal implantations (ectopic pregnancy) occurs in..% of prgnancy and causes…% of mother deaths

A

2
9

30
Q

3 types of abnormal implantations

A
  1. placenta previa = placenta blocks cervix/ exit= cause severe bleeding in late pregnancy
  2. tubal implantation= mejority of ectopic pregnancies occur in uterine tube (80% in ampulla)= cramping/ bleeding/ medical emergency diagnosed in weeks6-8
  3. abdominal implantation= egg enter abdomen through gap between ovary and uterine tube
31
Q

lithopaedion occurs in….when it remains…and the foetus dies
the foetus is too…to be…so instead it…
it is thought to protect the mother formt he necrotic tissue of the foetus

A

litho (stone)- paedion (child)
Abdominal pregnancy
undiagnosed
Large
reabsorbed
calcifies

32
Q

hydatidiform mole is

A

a results of abnormal fertilization of the oocyte (egg).
leads to an abnormal fetus.
The placenta grows normally with little or no growth of the fetal tissue.
The placental tissue forms a mass in the uterus

33
Q

2 types of hydatidiform mole

A
  1. complete= egg with no nucleus fertalised by 2 haploid sperms (enucleated oocyte)
    paternal imprinting= trophoblasts develops without embryo
    syncytiotrophoblasts produces hCG= positive pregnancy
  2. Partial= normal oocyte fertalised by 2 sperms (69XXY or 69XXX)= triploid zygote
    development of trophoblasts without embryonic tissue (or malformed embryo)= not compatible with life
34
Q

risks and solutions of hydatidiform moles

A
  1. complete= high hCG results in choriocarcinoma (cancer of placenta)
    require surgical/ medical management (Dand C)
  2. partial= moderately high hCG= moderate risl of choriocarcinoma
    spontaneously aborts (miscarry)
35
Q

in week 3, the…streak is formed
and the…of the embryo are firmly established

A

primitive streak
Cranial/ caudal and right/ left axis

36
Q

the process that transforms bilaminar disc to trilaminar disc is called…

A

gastrulation

37
Q

outline the steps of gastrulation

A
  1. formation of primitive streak (thick layer of epiblast that has cavity in middle/ pit)
  2. epiblasts move through pit and replace hypoblast cells= now called definitive endoderm (day 14-15)
  3. more epiblasts continue to move down (successive migration)= form middle layer= mesoderm (day 16)
  4. remaining top epiblast layer is now= ectoderm (day 16)
38
Q

3 parts of primitive streak

A
  1. primitive groove
  2. primitive node
  3. primitive pit
39
Q

the…plate is thicked portion of…that is in contact with…

A

prochordal
Endoderm
ectoderm

40
Q

derivatives of ectoderm layer

A

epidermis of skin (+ hair/ nails/ glands)
nervous tissue and sense organs
pituitary gland
adrenal medulla
enamel of teeth
lens of eye

41
Q

derivatives of mesoderm (lots of epithelia)

A

dermis of skin
epithelial lining of vessels/ lymph/ cavities
connective tissue (bone, cartilage etc)
adrenal cortex
Heart
kidneys and ureters
internal reproductive organs
spleen

42
Q

derivatives of endoderm (lots of glands)

A

epithelial lining of respiratory tract/ GI tract/ urinary bladder/ urethra
Gallbladder
Pancreas
thyroid gland
parathyroid gland

43
Q

2 conditions due to abnormal gastrulation

A
  1. sirenomelia= mermaid syndrome (due to lack of mesoderm tissues in caudal regions of embryo)= abnormalities of urogenital system and lower limbs
  2. Sacrococcygeal teratoma (most commone tumour in newborns)= when remainders of primitive streak give rise to tumour (most are benign and 80% in females)= resection to remove it
44
Q

abnormal gastrulation can also lead to….
2 types of inversus in patients

A

right to left asymmetry of body is reveresed= situs inversus
1. complete= harmless but 20% suffer from kartagener syndrome
2. partial= is much rarer and associated with other malformations ie: dextrocardia (isolated right sided heart)

45
Q

…is the first event in the development of the…
it is initiated by…from…to cause ectoderm to thicken and form the…from (neuroectoderm)

A

neurulation
CNS
signals
notochord
neural plate (induction)

46
Q

the steps of neurulation

A
  1. ectoderm proliferation (layer thickens)
  2. form neural plate
  3. neural fold (lateral edges of neural plate elevate), crest, groove form
  4. fusion to lateral sides to form nueral tube
47
Q

when the neural folds…, the neural tube is formed (day 22)
the…starts in…and continues…
the tube…from the surface ectoderm

A

fuse together
fusion, cervical (neck) region, cranially and caudally (both directions)
seperates

48
Q

the anterior (front/top) neuropore fuses on day…
the posterior neuropore fuses on day…
the cranial end of neural tube will form…
the caudal end will form…

A

25
28
brain
spinal cord

49
Q

failure of anterior neuropore to fuse causes…
failure of posterior neuropore to fuse causes…

A

anencephaly (brain does not form but a brainstem is present- heart/ lungs and some reflexes are present)

spinal cord does not form properly- paralysis
open neural tube prevent formation of vertebrae (spina bifida)
plate of neural tissue expoased at birth- infection

50
Q

as neural folds elevate and fuse, the neural crest cells…from the neural tube
they…laterally and ventrally and…into a variety of structure
sometimes refered to as…

A

Separate
migrate
differentiate
4th germ layer

51
Q

during 4th week, the embryo goes through…
the 2 directions are..

this is due to…

A

folding in 2 directions
1. craniocaudal folding
2. lateral folding

the differntial growth of amniotic sac and yolk sac (amniotic sac grows rapidly while yolk sac stays the same size)

52
Q

the….mesoderm starts dividning into blocks called…on day…
this beings in…and progresses towards…at rate of 3 or 4 pairs a day until 42-44 pairs form
it is a…process which helps with estimating…

A

Paraxial
somites
20
Cranial region
caudal region
predictable
age of embryo

53
Q

When the primitive streak closes up, the…forms
it then…with endoderm to form…
the plate then…and…to form a notochord (initiates neurulation)

A

notochordal process (hollow tube)
fuses, flattened notochordal plate
seperates from endoderm and fuses together

54
Q

2 roles of notochord:

A
  1. initiates neurulation (induction)
  2. initiates and organises formation of vertebrae from somites= induces differentiation of somites into 3 parts:
    - sclerotome (bone and cartilage)
    - myotome (skeletal muscle)
    - dermatome (dermis)
55
Q

notochord also organises the sclerotome cells as they form…
the notochord then….as the vertebrae form and its remains persist as…

A

the vertebral body and surround the neural tube to form certebral arch
Degenerate
nucleus pulposus of intervertebral discs

56
Q

abnormal induction of sclerotomes leads to…

A

spinal defects such as:
spina bifida (gap in spine)
Meningocele (cerebrospinal fluid fills the gap)
myolomeningocele (spinal cord and spinal nerves in the meningeal sac- with the fluid)

57
Q

…acid reduces neural tube defects (NTDs) such as…by…%

A

folic
Anecephaly, rachischisis, spina bifida
50-70%

58
Q

defects in neural crest cell development is:

A

neurofibromatosis- genetic disorder
mutation in neurofibromas 1 (NF1) gene which is a tumour suppressor (now switched off)= increased cell division
cause: benign tumours of nervous system, skin and cranial bones

59
Q

the connecting stalk is the future…

A

umbilical cord

60
Q

allantois is a…

A

sac connected to fetal bladder

61
Q

vitelline duct

A

Duct/ tube providing connection between yolk sac and midgut

62
Q

2 Ventral/ front body defects

A

ectopia cordis = lateral fold fails to fuse in thoracic region (chest) leaving the heart outside the body

Gastroschisis = lateral fold fails to fuse in abdominal region (intestine outside the body wall)

IMS 1 (14 decks)

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