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Embryology Flashcards

1
Q

Important genes of embryology

A
  1. Sonic hedgehog gene
  2. Wnt-7 gene
  3. FGF gene
  4. Homeobox (Hox) gene
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2
Q

embryology - Sonic hedgehog gene - location and function

A

Produced at base of limbs in zone of polarizing activity

Involved in patterning along AP axis and CNS delopment

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3
Q

Sonic hedgehog gene - mutation –>

A

holoprosencephaly

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4
Q

embryology - Wnt-7 gene - location

A

produced at apical ectodermal ridge (thickened ectodermal at distal end each devolving limb)

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5
Q

embryology - Wnt-7 gene - function

A

necessary for proper organization along dorsal-ventral axis

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6
Q

embryology - FGF gene - location and function

A

Produced at apical ectodermal ridge. Stimulates mitosis of underlying mesoderm, providing for lengthening of limbs

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7
Q

embryology - Homeobox (Hox) genes - location and function

A

involvd in segmental organisation of embryo in craniocaudal direction –> Code for transcription factors

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8
Q

embryology - Homeobox (Hox) genes - mutation

A

appendages in wrong location

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9
Q

The Zone of Polarizing Activity (ZPA) is an

A

area of mesenchyme that contains signals which instruct the developing limb bud to form along the anterior/posterior axis

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10
Q

early fetal development - fetalfertilization occurs at (when and where)

A 
day 0 (within 1 day of ovulation) 
ampulla of the uterine tube (upper end of fallopian tube)
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11
Q

early fetal development - fertilization - mechanism

A

sperm binds zona pellucida of the 2ry oocyte arrested in metaphasis of meiosis II –> triggers acrosome reaction (releasing of acrosomal enzymes (acrosin) that aids the sperm to penetrates the zona pellucida) –> cortical reaction (releasing of lysosomal enzymes that changes the oocyte cell membrane potential –> inactivates sperm receptor (polyspermy block)) fusion of both membranes

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12
Q

early fetal development - zona pellucida??

A

the thick transparent membrane surrounding a mammalian ovum before implantation.

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13
Q

early fetal development - fertilization - mechanism after the fusion of both membranes

A

sperm nuclear –> male pronucleus (and degeneration of tale and mitoch)
nucleus of the ovum –> female pronucleus
THE 2ry oocyte complets meiosis II –> mature ovum
–> Zyngamy

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14
Q

early fetal development - Zyngamy?

A

term that describe the succesful completion of fertilization (zygote formation) –> male and female pronuclei fuse and the cytoplasmic machinery for proper cell division exists

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15
Q

early fetal development -day of zygote formation

A

day 1

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16
Q

early fetal development - zygote life span

A

few hours –> its existence terminates when first cleavage division occurs

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17
Q

early fetal development - mechanism from zygote to morula

A

zygotes –> Cleavage (a series of mitotic divisions) –> blastula formation (consisting of cells called blastomeres) –> morula (a cluster of blastomeres 16-32)

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18
Q

early fetal development - morula formation - day and location

A

day 4. Location: uterine tube - uterine cavity

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19
Q

early fetal development - characteristics of cleavage in humans

A
  1. holoblastic (divide completely through their cytoplasm - tota)
  2. asymmetrical (the daughter cells are unequal in size)
  3. asynchronous (only one cell will divide at a time)
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20
Q

early fetal development - blastocyst formation - mechanism/day/topographical anatomy

A

day 5: occurs when fluid secreted within the morula (blastocyst cavity)
inner cell mass are celled embryoblast (pluripotent cells) –> embryo
outer cell masses are called trophoblast –> placenta

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21
Q

early fetal development - inner vs outer mass of blastocyst

A

inner cell mass are celled embryoblast (pluripotent cells) –> embryo
outer cell masses are celled trophoblast –> placenta

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22
Q

early fetal development - step after blasotcyts formation - mechansim/time/location

A

Implantation (days 6-10): degeneration of zona pelludica –> blastocysts implants within the posterior superior wall of uterus (within the functional layer of the endometrium) –> trophoblast differentiates into cytotrophblast and syncytiotrophoblast

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23
Q

trophoblast differentiates into

A
  1. cytotrophoblast

2. syncytiotrophoblast

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24
Q

hCG secretion begins ….(and by)

A

around the time of implantation of blastocyst (within 1 week) by syncytiotrophoblast

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25
Q

early fetal development - within week 2 events?

A

A. embryoblast differentiates into 2 distinct layers: 1. epiblast (dorsal) 2. hypoblast (ventral) (together are known as bilaminar disc)
B. syncytiotrophoblast continues its growth into endometrium (to contact vessels and glands). It does not divide mitotically. The cytotrophoblast divide mitotically, adding to the growth (primary chorinionic villli protrude into the syncytiotrophoblast)

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26
Q

early fetal development - bilaminar disc function

A
  1. epiblast –> amniotic fluid/also extraembryonic mesoderm

2. hypoblast –> migrate and line cytotrophoblast –> delimit a space –> yolk sac

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27
Q

early fetal development - trophoblast within week 2

A

syncytiotrophoblast continues its growth into endometrium (to contact vessels and glands). It does not divide mitotically. The cytotrophoblast divide mitotically, adding to the growth (primary chorinionic villli protrude into the syncytiotrophoblast)

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28
Q

Extraembryonic mesoderm

A

is a new layer of cells derived from epiblast:

  1. Extraembryonic somatic mesoderm –> lines cytotrophoblast –> forms connecting stalk and covers anion
  2. Extraembryonic visceral mesoderm –> covers yolk sac
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29
Q

early fetal development - week 3 - events

A
  1. Gastrulation

2. notochord formation

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30
Q

Gastrulation - definition

A

is the process that establishes the 3 primary germ layers (ectoder,, mesoderm, endoderm), forming a trilaminar embryonic disc

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31
Q

Gastrulation - mechanism

A

cells from epiblast invaginate –> primitive streak in the midline of epiblast –> 1. endoderm 2. mesoderm
3. endoderm

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32
Q

mesoderm is found between the

A

ectoderm (upp) and the endoderm (down)

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33
Q

Notochord formation (and function)

A

arises from midline mesoderm –> induces overlying ectoderm to differentiate into neuroectoderm and form neural plate

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34
Q

embryonuc period - when

A

weeks 3-8

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35
Q

All major organ systems begin to develop during the …. causing …

A

embryonuc period (weeks 3-8) causing craniocaudal and lateral body folding

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36
Q

during the embryonic period, the basic segmentation of the human embryo in craniocaudal direction is controlled by

A

Homeobox (Hox) gene

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37
Q

early fetal development - Weeks 3-8 (embryonic period) events

A
  1. neural tube formed by neuroectoderm and closes by week 4

2. organogenesis

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38
Q

early fetal development - week 4

A
  1. heart begins to beat

2. upper and loweer limb buds begin to form

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39
Q

early fetal development - week 6

A

fetal cardiac activity visible by transvaginal ultasound

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40
Q

early fetal development - week 8

A

fetal movement starts

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41
Q

early fetal development - week 10

A

genitalia have male/female characteristics

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42
Q

early fetal development - heart begins to beat and viddible in tranvaginal ultrasound - when

A

beat –> week 4

visible in US –> week 6

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43
Q

early fetal development - movement starts, genitalia have male/female characteristics , upper and lower limb buds begin to form - when

A

movement –> week 8
genitalia –> 10
limb buds –> week 4

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44
Q

early fetal development - when is extremely susceptible to teratogens

A

embryonic period (3-8 weeks)

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45
Q

Ectoderm is divided to

A
  1. surface ectoderm
  2. neuroectoderm
  3. Neural crest
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46
Q

Surface ectoderm derivatives

A
  1. epidermis
  2. anenohypophysis (from Rathke pouch)
  3. lens of eye
  4. epithelial lining of oral cavity
  5. sensory organs of ear
  6. olfactory epithelium
  7. anal canal below the pentinateline
  8. parotid
  9. sweet
  10. mammary glands
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47
Q

neuroectoderm derivatives

A
  1. Brain (neurohypophysis, CNS neuros, oligdendrocytes, astrocytes, ependymal cells, pineal gland)
  2. retina
  3. spinal cord
  4. CN 2
  5. Dilator and sphincter pupilae muscles
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48
Q

neural crest derivatives

A

PNS (dorsal root ganglia, cranial nerves, autonomic ganglia, Schwann cells), melanocytes, chromaffin cells off adrenal medulla, parafollicular (C) cells of thyroid, pia and arachnoid, bones of the skukk, odontoblasts, aorticopulmonary septum, endocardial cushions

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49
Q

mesoderm derivatives

A
  1. muscle 2. bone 3. connective tissue
  2. serous lining of body cavities (eg. peritoneum)
  3. spleen (from foregut mesentery) 6. cardiovascular structures 7. lymphatics 8. blood 9. wall of gut tube
  4. upper vagina 11. kidneys 12 adrenal cortex 13. dermis 14. testes 15 ovaries
  5. Notochord
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50
Q

postnatal derivatives of Notochord

A

nucleus polposus of intervertebral disc

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51
Q

Mesodermal defects

A 
mneomonic VACTERL 
Vertebral defects 
Anal atresia 
Cardiac defects
Tracheo-Esophageal fistula
Renal defects
Limb defects (bone and muscle)
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52
Q

Endoderm derivatives

A
  1. Gut tue epithelium (including anal canal above pectinate line)
  2. most urethrea and lower vagina(urogenital sinus)
  3. luminal epithelial derivtives (lungs, liver, gallbladder, pancreas, eustachian tube, thymus, parathyroid, thyroid follicular cells
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53
Q

Neuroectoderm derivatives (except CNS)

A
  1. retina
  2. CN 2
  3. Dilator and sphincter pupilae muscles
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54
Q

Neural crest derivatives (except PNS)

A
  1. melanocytes
  2. chromaffin cells off adrenal medulla
  3. parafollicular (C) cells of thyroid
  4. pia and arachnoid
  5. bones of the skull, odontoblasts
  6. aorticopulmonary septum
  7. endocardial cushions
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55
Q

tumor from surface ectoderm (definition and histology

A

Craniopharyngioma: benign Rathke pouch tumor with colesterol crystals, calcifications

56
Q

Types of errors in organ morphogenesis

A
  1. agenesis 2. aplasia 3. hypoplasia 4. disruption

5. deformation 6. malformation 7. sequence

57
Q

organ agenesis

A

abesnt organ due to absent primordial tissue

58
Q

A primordium is defined as

A

an organ or tissue in its earliest recognizable stage of development

59
Q

organ Aplasia

A

absent organ despite presence of primordial tissue (Failure to attain size or function)

60
Q

organ hypoplasia

A

incomplete organ development - primordial tissue present

61
Q

organ aplasia vs hypolasia

A

similar but hypoplasia is less severe

62
Q

organ disruption

A

2ry breakdown of previously normal tissue or structure (eg amniotic band syndrome)

63
Q

organ deformation

A

extrinsic disruption –> occurs after embryonic period

64
Q

organ malformation

A

intrinsic disruption –> occurs during embryonic period

65
Q

organ sequence

A

abnormalities result from a single 1ry embryologic event (eg. oligohydramnioos –> Potter sequence)

66
Q

is derivided from: adenohypophysis, gallbladder, spleen, bone, parafollicular C cells of thyroid, melanocytes, blood, mammary glands, parotid, kidneys

A

ectoderm: adenohypohysis, parotid, mamary glands
Neural crest: parafollicular C cells, melanocytes
mesoderm: spleen, bone, blood, kidneys
endoderm: gallbladder

67
Q

lens and retina of eye, optic nerve are derived from

A

lens –> surface ectoderm

optic nerve, retina –> neuroectoderm

68
Q

thymus, parathyroid, thyroid and adrenals are derived from

A

chromaffin cells of adrenal medulla, parafollicular (C) cells –> neural crest
thyroid follicular cells, thymus, parathryoid –> endoderm
adrenal cortex –> mesoderm

69
Q

skin is derived from

A

melanocytes –> neural crest
dermis –> mesoderm
epidermis –> Surface ectoderm

70
Q

epithelial lining of oral cavity, sensory organs of ear and oflactory epithelium are derived from

A

surface ectoder

71
Q

parotid, sweet parotid glands are derived from

A

surface ectoder

72
Q

anal canal is derived from

A

above pectinate line –> endoderm

below pectinate line –> ectoderm

73
Q

bones, muscles and connective tissue are derived from

A

bones of skull –> neural crest

connective tissue muscles, other bones –> mesoderm

74
Q

aorticopulmonary septum is derived from

A

neural crest

75
Q

cardiovascular structures, lymphatics, blood are derived from

A

all from mesoderm

(except aorticopulmonary septum and endocardial cushions –> neural crest)

76
Q

Endocardial cushions refer to

A

a subset of cells in the development of the heart that play a vital role in the proper formation of the heart septa

77
Q

odontoblast are derived from

A

neural crest

78
Q

pia and dura are derived from

A

neural crest

79
Q

serous lining of bodies are derived from

80
Q

GI is derived from

A 
gut epithelium (including anal canal above pectinate line), liver, gallbladderm pancreas --> endoderm
spleen, gut wall --> mesoderm (foregut mesentery)
81
Q

urogenital organs are derived from

A

upper vagina, kidneys, testes, ovaries –> mesoderm

most of urethra, lower vagina, eustachian tube –> endoderm

82
Q

vagina and lung are derived from

A

lungs –> endoderm
upper vagina –> mesoderm
lower vagina endoderm (urogenital sinus)

83
Q

teratogens effects according to period

A

before week 3 –> all-or-none
3-8 weeks (embryonic period - most suscpetible)
after 8 weeks –> growth and function affected

84
Q

Antibiotics to avoid in pregnancy (and why)

A
  1. Sulfonamides –> Kernicterus
  2. Amniglycosides –> Ototoxicity
  3. Fluoroquinolones –> Cartilage damage
  4. macrolides –> embryotoxic
  5. tetracyclines –> DIscolored teeth, inhibiton of growth
  6. Chloramphenicol –> Gray babe syndrome
  7. Griseofluvin –> teratogenic
  8. Ribavirin (antiviral)
85
Q

drugs and substance that affect pregnancy (beside antibiotics) (14)

A
  1. ACE inhibitors 2. Alkylating agents 3. Antiepileptics
  2. Diethylstibestrol 5. Folate antagonists
  3. Isotretinoin 7. Lithium 8. Methimazol
  4. Thalidomide 10. Warfarin 11. Alcohol 12. Cocaine
  5. Smoking (nicotine, CO) 15. others factors
86
Q

Other factors that affect fetus

A
  1. iodine (lack or excess)
  2. Maternal diabetes
  3. Methylmercury
  4. Vitamin A excess
  5. X-rays
87
Q

Leading cause of low body weight in in developed countries

88
Q

Leading cause of intellectual disability in USA

A

Fetal alcohol syndrome

89
Q

Fetal alcohol syndrome - Most severe form

A
  1. heart-lung fistulas

2. holoprosnecephaly

90
Q

Dizygotic (fraternal) twins arise from …. (explain)

A

2 eggs that are sperated by 2 different sperm (2 zygotes) and will have 2 separate amniotic sacs and 2 separate placenta (chorions)
(DICHORIRIONIC DIAMNIOTIC)

91
Q

Dizygotic (fraternal) twins - mechanism - how many eggs, sperms, zygotes, amniatic sacs and placenta

A

all 2

DICHORIRIONIC DIAMNIOTIC

92
Q

Monozygotic (identical) twins arise ….(explain)

A

from 1 ferilized egg (1 egg + 1 sperm) that splits ine early pregnancy. The timing of cleavage determines chorionicity (number of chorions) and amnionicity (number of amnions)

93
Q

Monozygotic (identical) twins - types of process (and proportions)

A
  1. Dichorionic diamniotic (25%)
  2. Monochorionic diamniotic (75%)
  3. Monochorionic monoamnitotic (rare)
  4. Monochorionic monoamniotic (conjoint - rare)
94
Q

Monozygotic (identical) twins - types of process and mechanism (and proportions)

A
  1. Dichorionic diamniotic - if cleavage before morula formation (0-4 days) (25%)
  2. Monochorionic diamniotic - if cleavage after morla formation and before blastocyst (4-8 days) (75%)
  3. Monochorionic monoamnitotic - if cleavage after blastocyst formation and before bilaminar embryonic disc formation (8-12 days) (rare)
  4. Monochorionic monoamniotic if cleavage or axis duplication after bilaminar embryonic disc formation (> 13days) (conjoint - rare)
95
Q

Placenta is formed when

A

the embryo invades the endometrium of the uterus and when the trophoblast forms villous chorion

96
Q

villous chorion formation goes through stages

A

primary, secondary, teriary chorionic villi

97
Q

Placenta components are divided to

A
  1. fetal component

2. maternal component

98
Q

Placenta - fetal component (and area)

A
  1. cytotrophoblast (inner layer of chorionic villi)

2. syncytiotrophoblast (outer layer of chorionic villi)

99
Q

Synctitiotrohoblast - function

A

synthesize and secretes hormones –> hCG

100
Q

hCG secretion begins ….(and by)/ structure/functiom

A 
around the time of implantation of blastocyst (within 1 week) by syncytiotrophoblast 
structure: stracturally similar to LH
function --> stimulates corpus luteum to secrete progesterone during first trimester
101
Q

Synctitiotrohoblast - special characteristic

A

lacks MHC I expression –> low chance of attack by maternal immune system

102
Q

Placenta - maternal component

A

Decidua basalis

103
Q

Placenta - decidua basalis derived from/function

A

endometrium (between blastocysts and myometrium)

maternal blood in lacunae

104
Q

substance from maternal circulation to fetal circulation

A

O2, H20, elctrolytes, nutritiens, hormones, IgG, drugs, viruses

105
Q

microbes that pass from materan to fetal circulation

106
Q

substance from fetal circulation to maternal lcirculation

A

CO2, H20, urea, hormones, wasted products

107
Q

chorionic plate

A

the part of the fetal placenta that gives rise to chorionic villi, which attach to the uterus during the early stage of formation of the placenta.

108
Q

Chorionic villi are

A

villi that sprout from the chorion to provide maximum contact area with maternal blood.

109
Q

fetal circulation - blood entering fetus through …

PO2 and saturation

A

umbilical vein (O2 rich)
30mmHg
80%

110
Q

fetal circulation - 3 important shunts and puprose

A
  1. ductus venosous –> umbilical vein to IVC (bypass hepatic circulation)
  2. foramen ovale –> RA to LA
  3. ductus arteriosus –> main pulmonary artery to descending aorta
111
Q

physiologic closure of foramen ovale

A

at birth, infants take a breath–> decreased resistance in pulmonary vasculature –> increased LA pressure vs RA pressure –> foramen ovale closes

112
Q

fetal circulation - 3 important shunts and their postnatal derivatives

A
  1. ductus venosous –> ligamentum venosum
  2. foramen ovale –> fossa ovalis
  3. ductus arteriosus –> ligamentum arteriosum
113
Q

hCG detection (when)

A

maternal blood at 1 week

maternal urine at 2 week (home test)

114
Q

umbilical cord - definiton

A

conduit between the developing embryo or fetus and the placenta

115
Q

umbilical cord - structure (and contains)

A

two arteries (the umbilical arteries) and one vein (the umbilical vein), allantoic duct, buried within Wharton’s jelly, surrounded by amnitotic epithelium (cord lining membrane)

116
Q

umbilical vein drains into IVC via

A

liver or via ductus venosus

117
Q

umbilical arteries return deoxygenated blood from …. to …..

A

fetal internal iliac arteries to placenta

118
Q

umblical vein + umbilical arteries - postnatal derivatives

A

umblical vein –> Ligamentum teres hepatis (Round ligament)

umbilical arteries –> medial umbilical ligaments

119
Q

Umbilical arteries and vein are derived from

120
Q

allanotis urachus correlation

A

urachus is part of allantoic duct between bladder and umbilicus

121
Q

allantois (–>urachus) - postnatal derivatives

A

Median umbilical ligament

122
Q

Single umbilical artery (2 vessel cord) is associated with

A

congenital and chromosomal anomalies

123
Q

Urachus - everything

A

in 3rd week the yolk sac forms the allantois –> extentds into urogenital sinus –> Allantois becomes the urachus, a duct between fetal bladder and umbilicus

124
Q

urachus?

A

a duct between fetal bladder and umbilicus

125
Q

pathology associated with urachus

A
  1. patent urachus
  2. urachal cyst
  3. Vesicourachal diverticulum
126
Q

patent urachus - mechanism

A

total failure of to obliterate –> urine discharge from umbilicus

127
Q

urachal cyst - mechanism

A

partial failure of to obliterate –> fluid-filled cavity lined with uroepithelium, between umbilivus and bladder

128
Q

urachal cyst - complications

A
  1. infections

2. adenocarcinoma

129
Q

Vesicourachal diverticulum - mechanism

A

slight failure of urachus to obliterated –> outpouching of bladder

130
Q

not a neural structure derived from neuroectoderm

A

dilator and sphincter papilae muscles

131
Q

vitelline duct - AKA/definition

A

omphalomesenteric duct

long narrow tube that joins the yolk sac to the midgut lumen of the developing fetus

132
Q

fate of vitelline duct

A

obliteration at 7 weeks

133
Q

disease associated with vitelline duct

A
  1. vitelline fistula
  2. Meckel diverticulim
  3. omphalomesenteric cysts
134
Q

vitelline fistulla - presentation

A

meconium discharge

135
Q

Meckel diverticulum the rule of 6 2s

A 
2 times as likely in males
2 inches long
2 feet from ileocecal valce
2% of population
present in first 2 yeras of life
may have 2 types of epithelial (gastric/pancreatic)
136
Q

meckel diverticulum - mechanism presentation

A
  1. melena (or hematochezia) 2. RLQ pain 3. intussusception 4. volvulus
  2. obstruction near terminal ileum (mimics appendicitis)
    MC asymptomatic
137
Q

twinning - dizygotic (fraternal) vs monozygotic according to frequency

A

dizygotic (fraternal) –> 2/3

monozygotic –> 1/3

Reproductive (20 decks)

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