Embryology

Front 1

zygote

Back 1

sperm + egg

Front 2

embryo

Back 2

zygote --> 8 weeks (3 germ layers)

Front 3

fetus

Back 3

from 3rd month to delivery

Front 4

greatest susceptability to malformations

Back 4

week 3-8

Front 5

primordium

Back 5

beginning of first discernable structure

Front 6

when do male germ cells begin developing?

Back 6

dormant until puberty then begin mitosis and meiosis

Front 7

when do female germ cells begin meiosis?

Back 7

at birth (primary follicle) and complete development at puberty

Front 8

stages of egg development inside ovary

Back 8

primary follicle, follicle grows, primary oocyte develops into secondary oocyte + polar bodies

Front 9

stimulation for pituitary gland to release FSH and LH

Back 9

hypothalamus released gonadotrophin releasing hormone

Front 10

what hormone causes follicles to mature?

Back 10

FSH

Front 11

what do developing follicles produce?

Back 11

estrogen (thickens endometrium)

Front 12

what does spike in LH cause?

Back 12

ovulation

Front 13

what is the corpus luteum? what does it do?

Back 13

forms from empty follicle cells, secretes progesterone which maintains lining of uterus

Front 14

what happens if there is implantation?

Back 14

HCG produced by embryo which signals the corpus luteum to stay, maintaining the wall

Front 15

what happens if there is no implantation?

Back 15

corpus luteum breaks down and wall sloughs off

Front 16

where does fertilization happen?

Back 16

ampulla

Front 17

capacitation

Back 17

glycoprotein coat and seminal proteins are removed from acrosome --> sperm releases hormones that can penetrate zona pellucida

Front 18

blastula

Back 18

ball of dividing cells (up to 32) on its way to uterus, does not increase in size

Front 19

morula

Back 19

32 cells

Front 20

embryoblast

Back 20

comes from inner cell mass, gives rise to embryo

Front 21

trophoblast

Back 21

comes from outer cell mass, becomes the placenta

Front 22

blastocyst

Back 22

morula + fluid filled cavity that breaks out of zona pellucida

Front 23

2nd week layer split

Back 23

epiblast and hypoblast

Front 24

where does amniotic cavity develop?

Back 24

within epiblast cells

Front 25

bilaminar disc

Back 25

epiblast and hypoblast cells

Front 26

when is implantation?

Back 26

day 7

Front 27

how does implantation happen?

Back 27

specialized trophoblasts invade uterus

Front 28

trophoblastic lacuna

Back 28

going to anastomose with maternal blood

Front 29

hypoblasts migrate around and form which cavity?

Back 29

yolk sac

Front 30

extraembryonic mesoderm forms which cavity?

Back 30

chorionic cavity

Front 31

gastrulation

Back 31

establishment of all three germ layers of the embryo

Front 32

primitive streak

Back 32

midline structure that forms in the epiblast near caudal end with the primitive pit at the end of it, establishes longitudinal axis

Front 33

primitive pit

Back 33

eventually become the head

Front 34

destiny for 1st epiblast cells that migrate into primitive streak

Back 34

endoderm

Front 35

destiny for 2nd epiblast cells that migrate into primitive streak

Back 35

mesoderm (become notochord)

Front 36

paraxial mesoderm gives rise to?

Back 36

axial skeleton, voluntary muscles, part of the dermis

Front 37

intermediate mesoderm gives rise to?

Back 37

urinary system, parts of genital system

Front 38

lateral mesoderm gives rise to?

Back 38

most of dermis, parts of limb, visceral lining

Front 39

two regions without mesoderm

Back 39

buccopharyngeal membrane and cloacal membrane

Front 40

first 7 somitomeres give rise to?

Back 40

striated muscle of face, jaw and throat

Front 41

first 4 somites?

Back 41

occipital part of skull

Front 42

next 22 somites?

Back 42

vertebrae and associated muscles

Front 43

somites develop into 3 subdivisions

Back 43

myotomes, dermatomes, sclerotomes

Front 44

what to myotomes turn into?

Back 44

myogenic cells

Front 45

what do sclerotomes turn into?

Back 45

vertebrae

Front 46

what do dermatomes turn into?

Back 46

dermis

Front 47

neural plate

Back 47

thickening of epiblasts cranial to the primitive pit

Front 48

spina bifida occulta

Back 48

tuft of hair

Front 49

spina bifida meningocele

Back 49

CNS forms a bulge

Front 50

spina bifida meningomyelocele

Back 50

spinal cord bulges out

Front 51

lateral plate mesoderm divided into 2 layers...

Back 51

somatic and splanchnic

Front 52

intraembryonic coelom

Back 52

space between lateral mesoderm layers, eventually becomes closed off

Front 53

what does somatic mesoderm eventually form?

Back 53

parietal layer of mesothelium on the body wall surfaces of cavities

Front 54

what does splanchnic mesoderm eventually form?

Back 54

visceral layer of mesothelium lining the organs

Front 55

mesentary

Back 55

place where visceral and parietal linings are continuous

Front 56

first structure to divide the coelom into thoracic and abdominal cavities

Back 56

septum transversum

Front 57

4 components of diaphragm

Back 57

septum transversum, pleuroperitoneal membranes, esophageal membrane, muscle from body walll

Front 58

pleuropericardial folds

Back 58

ridges of mesenchyme that grow and fuse, separating pericardial and pleural cavities

Front 59

lungs derived from...

Back 59

foregut (continuously bifurcates to create their structure)

Front 60

diagphragmatic hernia

Back 60

occurs on L because it is last to close

Front 61

stomach's first appearance

Back 61

spindle shape in foregut suspended by mesogastria

Front 62

describe changes occurring in stomach

Back 62

dorsal side grows quickly and ventral side grows slowly --> 90 degree rotation --> dorsal side becomes greater curvature and ventral side becomes lesser curvature, dorsal mesogastrium becomes greater omentum

Front 63

where does the spleen come from?

Back 63

mesodermally derived (comes from dorsal mesogastrium)

Front 64

hepatic diverticulum

Back 64

endodermally derived, outgrowth from duodenum, becomes the bile duct (gives off 2nd diverticulum to become the gall bladder and cystic duct)

Front 65

pancreatic diverticulum

Back 65

2, dorsal (upper half) and ventral (lower half), fuse to become one

Front 66

primary intestinal loop

Back 66

snakes from foregut out to vitelline duct back around toward hindgut and herniates into the umbilical cord

Front 67

rotation of midgut

Back 67

rotates CCW 90 degrees around SMA axis then retracts from umbilicus and rotates 180 degrees CCW

Front 68

cephalic limb of intestinal loop becomes...

Back 68

2nd half of duodenum, jejunum and part of ileum

Front 69

Meckel's Diverticulum

Back 69

a portion of the vitelline duct persists and can cause appendicitis-like symptoms

Front 70

if entire vitelline duct still persists...

Back 70

can get feces out umbillicus

Front 71

where do embryonic blood vessels form?

Back 71

splanchnic layer of lateral mesoderm

Front 72

what is cardiogenic area?

Back 72

blood islands in horseshoe shape crainial to neural plate

Front 73

where do dorsal aortae form?

Back 73

splanchnic layer of lateral mesoderm

Front 74

how is pericardial cavity formed?

Back 74

angiogenic cells developing in splanchnic mesoderm creates tubes that fuse on the midline (while gut tube is forming)

Front 75

endocardium comes from?

Back 75

fusing heart tubes

Front 76

myocardium comes from?

Back 76

splanchnic mesoderm from a layer adjacent to tubes

Front 77

epicardium comes from?

Back 77

splanchnic mesoderm

Front 78

dorsal mesocardium

Back 78

fusion of mesoderm layers between gut and heart, eventually breaks down, forms transverse sinus of pericardium

Front 79

blood flow through primitive heart

Back 79

through sinus venosus --> primitive atria --> primitive ventricle --> bulbus cordis --> aortic sac --> dorsal aortae

Front 80

where is truncus arteriosus?

Back 80

crainial end of bulbus cordis

Front 81

why does heart begin to bulge and fold?

Back 81

grows faster than rest of embryo and it is fixed at its ends by aortic arches and septum transversum

Front 82

bulboventricular loop

Back 82

folding between bulbus cordis and primitive ventricle

Front 83

adult left ventricle comes from

Back 83

mostly primitive ventricle

Front 84

adult right ventricle comes from

Back 84

inferior end of bulbus cordis

Front 85

outflow regions of adult left and right ventricles come from

Back 85

superior end of bulbis cordis (conus cordis)

Front 86

trabeculated portions of right and left atrium come from

Back 86

primitive atria

Front 87

ascending aorta and pulmonary artery come from

Back 87

truncus arteriosus

Front 88

adult coronary sinus comes from

Back 88

left and transverse portion of sinus venosus

Front 89

smooth-walled portion of right atrium comes from

Back 89

right portion of sinus venosus

Front 90

What is commandeering?

Back 90

Commandeering is when the federal gov passes a statute that requires a state to pass a statute. Fed gov can’t do this.

Congress cannot compel state regulatory or legislative action
a. NY v US: nuclear waste: Congress was commandeering

b. But Congress can induce state government action by putting strings
on grants, so long as the conditions are expressly stated and relate to
the purpose of the spending program

i. Drinking age tied to state receiving highway money

ii. Or imposing a uniform child custody law upon all the states
thru the taxing and spending power, making an allocation of
funds available to each state that adopts the uniform law

Front 91

endocardial cushions

Back 91

outgrowths of mesenchyme on dorsal and ventral walls grow and fuse medially --> right and left atrioventricular canals

Front 92

AV valves formed by

Back 92

thinning of myocardium surrounding atrioventricular canals

Front 93

septum primum

Back 93

grows from roof of common atrium toward endocardial cushion, creates foramen primum

Front 94

foramen secundum

Back 94

formed after septum primum fuses with endocardial cushion

Front 95

septum secundum

Back 95

grows from the right of where septum primum began its growth

Front 96

foramen ovale

Back 96

created between septum primum and septum secundum, allows blood flow between atria

Front 97

how does foramen ovale close?

Back 97

at birth, high pressure in left atrium pushes them together

Front 98

aorticopulmonary septum

Back 98

forms from truncal and bulbar ridges that grow and rotate --> division in the medial plane (from neural crest cells)

Front 99

interventricular septum

Back 99

forms from muscular outgrowth first that meets up with membranous portion derived from truncal and bulbar ridges and endocardial cushions

Front 100

intraventricular foramen

Back 100

opening between 2 ventricles until membranous portion of ventricular septum grows

Front 101

ventricular septal defects

Back 101

left to right shunt of blood usually because endocardial cushion did not close foramen

Front 102

probe patent forament ovale

Back 102

usually of no clinical significance

Front 103

secundum atrial septal defect

Back 103

patent forament ovale from septum primum being too short or containing fenestrations

Front 104

persistent truncus arteriosus

Back 104

bulbar and truncal ridges failed to create septum, almost always has VSD, mixture of oxygenated and deoxygenated blood sent to body

Front 105

transposition of great vessels

Back 105

aorta comes from right ventricle and pulmonary atrium comes from left, result of no spiraling while developing, causes cyanosis

Front 106

overriding aorta

Back 106

unequal division causes huge aorta that blocks VSD

Front 107

tetralogy of Fallot

Back 107

pulmonary stenosis, overriding aorta, ventricular septal defect and right ventricular hypertropy (main problem is misaligned septum)

Front 108

blood vessels begin as...

Back 108

aggregations of cells in the mesoderm

Front 109

aortic arches

Back 109

develop in mesenchymal swellings around pharynx, arises from aortic sac and terminates in dorsal aortae

Front 110

fate of 1st aortic arch

Back 110

mostly regresses, part of it forms maxillary arteries

Front 111

fate of 2nd aortic arch...

Back 111

mostly regresses, part of it forms stem of stapedial arteries

Front 112

fate of 3rd aortic arch...

Back 112

form common carotids then part of internal carotids then external carotids

Front 113

fate of 4th aortic arch...

Back 113

left arch forms midportion of arch of aorta, right arch forms proximal part of right subclavian

Front 114

aortic sac forms...

Back 114

proximal arch of the aorta and bracheocephalic artery

Front 115

left dorsal aorta forms...

Back 115

distal arch of aorta

Front 116

distal right subclavian artery formed from...

Back 116

7th intersegmental artery

Front 117

fate of 5th aortic arches...

Back 117

regress

Front 118

fate of 6th aortic arches...

Back 118

proximal left: proximal part of left pulmonary artery, distal left: ductus arteriosus, proximal right: proximal part of right pulmonary artery, distal right: regresses

Front 119

recurrent laryngeal nerves hook around...

Back 119

6th aortic arch

Front 120

crainial dorsal aortae help form...

Back 120

internal carotids

Front 121

intersegmental arteries form...

Back 121

vertebral arteries, intercostal artiers, lumbar arteries, sacral arteries

Front 122

vitelline arteries form...

Back 122

celiac, SMA, IMA

Front 123

umbilical arteries form...

Back 123

common iliac arteries

Front 124

7th cervical intersegmental arteries contribute to...

Back 124

right and left subclavian arteries

Front 125

patent ductus arteriosus

Back 125

usually closes because of high PO2 (--> inhibits prostaglandin production)

Front 126

umbilical veins carry blood from...

Back 126

chorion (oxygenated)

Front 127

vitelline veins carry blood from...

Back 127

yolk sac, then GI

Front 128

common cardinal veins receive blood from...

Back 128

posterior and anterior cardinal veins

Front 129

what happens to the proximal left vitelline vein?

Back 129

disappears --> blood from left side drains to right side

Front 130

vitelline veins form...

Back 130

plexus that passes through the septum transversum (invades liver tissues)

Front 131

ductus venosus

Back 131

formed from parts of vitelline plexus, shunts half of oxygenated blood to right atrium via the inferior vena cava

Front 132

right vitelline veins forms...

Back 132

(from inferior to superior): portal vein, SMV, hepatic vein, hepatic part of IVC

Front 133

only part of the umbilical veins that does not regress...

Back 133

caudal left

Front 134

caudal left umbilical vein anastomoses with...

Back 134

ductus venosus and both become ligmentum venosum and ligamentum teres after birth

Front 135

left brachiocephalic vein forms from...

Back 135

anterior cardinal veins

Front 136

internal jugular veins form from...

Back 136

cranial portions of anterior cardinal veins

Front 137

superior vena cava forms from...

Back 137

right common cadinal vein and portion of right anterior cardinal vein

Front 138

posterior cardinal veins are obliterated and replaced by...

Back 138

subcardinal, sacrocardinal, supracardinal

Front 139

subcardinal veins become...

Back 139

renal, suprarenal and gonadal veins

Front 140

subcardinal, sacrocardinal and supracardinal all contribute to...

Back 140

IVC and azygous system

Front 141

if left and right anterior cardinal veins do not adequately anastomose...

Back 141

persistent SVC that empties into the coronary sinus

Front 142

pronephros

Back 142

non-functional, transient kidney system

Front 143

mesonephros

Back 143

transiently functional

Front 144

metanephros

Back 144

forms permanent kidney

Front 145

mesonephric excretory unit

Back 145

Bowman's capsule and glomerulus form rudimentary excretory unit, functional