Anatomy-Embryology-Exam 1

Front 1

How does Shh expression from the notochord function?

Back 1

Induces neural plate to ventralize and the floor plate to form by repression of PAX and MSX(basal plate)

Front 2

What does the mantle layer include?

Back 2

Basal plate, alar plate, sulcus limitans, roof and floor plate and intermediolateral cell column

Front 3

What is the basal plate?

Back 3

ventral horn-motor

Front 4

What is the alar plate?

Back 4

dorsal horn-sensory

Front 5

Fetal Landmarks Day 0

Back 5

Fertilization by sperm forming zygote, initiating embryogenesis

Front 6

Fetal Landmarks within week1

Back 6

hCG secretion begins after implantation of blastocyst

Front 7

Fetal Landmarks within week 2

Back 7

bilaminar disc (epiblast, hypoblast)

Front 8

Fetal Landmarks within week 3

Back 8

Gastrulation, Primitive streak, notochord, and neural plate begin to form.

Front 9

Fetal Landmarks weeks 3-8

Back 9

Neural tube formed by neuroectoderm and closes by week 4. Organogenesis. Extremely susceptible to tetragens

Front 10

Fetal Landmark week4

Back 10

Heart begins to beat. Upper and lower limb buds begin to form

Front 11

Fetal Landmarks week 8

Back 11

Fetal movement, fetus looks like baby

Front 12

Fetal Landmarks week 10

Back 12

Genitalia have male/female characterisitics

Front 13

Rule of 2's for 2nd week

Back 13

2 germ layers(bilaminar disk): epiblast, hypoblast.
2 cavities: amniotic cavity, yolk sac.
2 components to placenta:cytrophoblast, syncytiotrophoblast.

Front 14

Rule of 3's for 3rd week

Back 14

The result of gastrualation is formation of 3 germ layers(gastrula): ectoderm' mesoderm, endoderm--three structures(primitive streak, notochord and neural plate) and a third fetal membrane(allantosis)

Front 15

Describe Blastocyst Formation

Back 15

Fertilization of the ovum initiates mitosis of the zygote to form blastomeres.
The blastomeres continue to divide forming a solid mass of cells termed the morula.
The morula is contained within an amorphous membrane the zona pellucida.
The zona pellucida disappears as the morula enters the uterine cavity (day 4).
Day 5 The morula is a solid ball of about 16 undifferentiated, spherical cells. As cell division continues in the morula, the blastomeres change their shape and tightly align themselves against each other. This is called compaction and is likely mediated by cell surface adhesion glycoproteins.

Front 16

What is the embryoblast?

Back 16

The internal cells of the blastocyst are termed the inner cell mass

Front 17

What is the trophoblast – trophectoderm.

Back 17

the surrounding cells are the outer cell mass of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg.

Front 18

What is the blastocyst.

Back 18

A cavity (blastocoele) develops within the morula and, at this point, is termed a blastocyst.It possesses an inner cell mass (ICM), or embryoblast, which subsequently forms the embryo, and an outer layer of cells, or trophoblast, which later forms the placenta.

Front 19

The outer cell mass (trophoblast) gives rise to two components of the placenta

Back 19

The Syncytiotrophoblast and the Cytotrophoblast

Front 20

What is the Syncytiotrophoblast?

Back 20

an amorphous multinucleated layer that erodes into the endometrium and maternal blood vessels.Lacunar spaces soon form within the syncytiotrophoblast and will fill with maternal blood.

Front 21

What is the Cytotrophoblast?

Back 21

mononucleated cell layer that gives rise to the syncytiotrophoblast.

Front 22

What do L-Selectins do?

Back 22

carbohydrate binding proteins on the trophoblastic cells that bind to carbohydrate receptors on the endometrial lining cells which initiates “capture” of the blastocyst to the endometrium.

Front 23

What do Integrin molecules do?

Back 23

molecules expressed by the trophoblast attach to the endometrium via receptor sites on laminin molecules in the extracellular matrix of the endometrium.

Front 24

What is function of Fibronectin molecules?

Back 24

are responsible for migration of the blastocyst into the endometrium.
All of these molecules ( l-Selectins, Integrins and Fibronectin) interact to promote differentiation of the trophoblast.

Front 25

Where does Extraembryonic mesoderm fit?

Back 25

will be added to the inner surface of the cytotrophoblast to complete the third layer of the placenta.

Front 26

What is the Hypoblast?

Back 26

the primitive endoderm that gives rise to the exocoelomic membrane that lines the primary yolk sac.

Front 27

What is the Epiblast?

Back 27

is adjacent to the trophoblast and gives rise to all three definitive germ layers of the embryo

Front 28

What is function of Amnioblasts?

Back 28

are derived from the epiblast and form the amniotic membrane over the disc.

Front 29

What is Extraembryonic mesoderm?

Back 29

is derived from the primary yolk sac and epiblast and fills the blastocyst cavity.

Front 30

What is the Chorionic Cavity?

Back 30

forms within the extraembryonic mesoderm and divides it into splanchnopleuric and somatopleuric extraembryonic mesoderm.

Front 31

Basics of nervous system formation

Back 31

nervous system develops from ectoderm of the germ disc. The notochord and adjacent mesoderm induce the overlying ectoderm to form a neural plate that ultimately becomes the neural tube which will differntiate into brain and spinal cord

Front 32

Neural tube formation

Back 32

fusion begins in midportion of neural groove and extends in both cranial and caudal directions. the cranial(anterior) neuropore closes about day 25 and the caudal(posterior )neuropore closes about 2 days later.
The completely closed neural tube detaches form the ectoderm and sinks into the underlying mesoderm

Front 33

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Back 33

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Front 34

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Back 34

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Front 35

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Back 35

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Front 36

What signals the beginning of gastrulation?

Back 36

The primitive streak appears at the caudal end of the germ disc within the epiblast and signals the beginning of gastrulation.

Front 37

The primitive streak consists of what?

Back 37

the primitive groove, primitive node, and primitive pit.
Cells that move through the primitive streak will replace the hypoblast to form the definitive endoderm and also establish the intraembryonic mesoderm. It is the structure that imparts bilateral symmetry to the embryo as well as craniocaudal aspects

Front 38

What about cells that remain in the epiblast

Back 38

They become the definitive ectoderm.

Front 39

Cells that move through the primitive node form what?

Back 39

the prechordal plate, notochord, and paraxial mesoderm.

Front 40

What is Gastrulation?

Back 40

is the event in the 3rd week of development that results in formation of the definitive germs layers (ectoderm, mesoderm, and endoderm), three structures (primitive streak, primitive node, and neural plate), and a third fetal membrane (allantois).

Front 41

What is involved in beginning of gastrulation?

Back 41

Gastrulation begins with the appearance of the primitive streak. Epiblast cells move to the primitive streak and move beneath the epiblast by the process of invagination.

Front 42

What is Gastrulation?

Back 42

is the event in the 3rd week of development that results in formation of the definitive germs layers (ectoderm, mesoderm, and endoderm), three structures (primitive streak, primitive node, and neural plate), and a third fetal membrane (allantois).

Front 43

What is involved in beginning of gastrulation?

Back 43

Gastrulation begins with the appearance of the primitive streak. Epiblast cells move to the primitive streak and move beneath the epiblast by the process of invagination.

Front 44

Mesoderm does not infiltrate two areas of the germ disc...what are they?

Back 44

Buccopharyngeal membrane and the Cloacal membrane

Front 45

What is the Buccopharyngeal membrane?

Back 45

future opening of the oral cavity.Buccopharyngeal membrane is normally gone by the 4th week of development

Front 46

What is the Cloacal membrane?

Back 46

future anal membrane.
and the cloacal membrane by the 7th week.

Front 47

What is the Prechordal plate?

Back 47

a dense cluster of midline mesodermal cells that migrated through the primitive pit. These cells are responsible for induction of the forebrain in the overlying ectoderm.

Front 48

What do Prenotochordal cells do?

Back 48

form the hollow notochord process which extends to the prechordal plate from the primitive pit.Notochord process fuses with the hypoblast.

Front 49

How is the Definitive notochord formed?

Back 49

As the hypoblast is being replaced with endoderm, the prenotochordal cells lift form the hypoblast and form the definitive notocord

Front 50

The Neurenteric canal functions to

Back 50

brings amniotic and yolk sacs into continuity for a brief time.
The notochord has an inductive role in neural plate formation and forms the center axis for the axial skeleton and associated musculature.

Front 51

When does the The primitive streak disappear?

Back 51

will persist until the end of the 4th week of development and eventually disappears.

Front 52

Occasionally remnants of primitive streak will persist and may give rise to multiple tissue tumors called

Back 52

sacrococcygeal teratomas.

Front 53

Teratomas may also arise from _______________ that do not make the complete migration to the developing gonads.
Teratomas may arise within the gonads as well.

Back 53

primordial germ cells

Front 54

What is derived from the primitive node and primitive streak?

Back 54

Intraembryonic mesoderm

Front 55

What is derived from cranial portion of node.

Back 55

Prechordal Plate

Front 56

What is the Notochord derived from?

Back 56

from cranial portion of node.

Front 57

What is derived from the node and cranial portion of primitive streak.

Back 57

Paraxial mesoderm

Front 58

Where does the Intermediate mesoderm come from?

Back 58

from mid primitive streak.

Front 59

Lateral plate mesoderm is derived from what?

Back 59

from caudal primitive streak.

Front 60

What is derived from most caudal primitive streak?

Back 60

Extraembryonic Mesoderm

Front 61

What is Anterior Visceral Endoderm (AVE)?

Back 61

express transcription factors essential for head formation

Front 62

What does Nodal do?

Back 62

initiates and maintains primitive streak

Front 63

What do Bone Morphogenetic Protein-4 (BMP-4) and Fibroblastic Growth Factor (FGF) do?

Back 63

work in concert to ventralize mesoderm that contributes to kidneys, blood, and body wall mesoderm.

Front 64

What do Noggin, Chordin, and Follistatin do?

Back 64

are expressed in the primitive node and antagonize(inhibit expression) the action of BMP-4 that results in dorsalization of notochord and paraxial mesoderm (head region of germ disc).

Front 65

What does the Brachyury (T) gene do?

Back 65

Regulates dorsal mesoderm formation in the caudal region of germ disc. Absence of this gene’s expression results in sirenomelia (caudal dysgenesis).
The "mermaid baby"

Front 66

What is function of Hepatic Nuclear Factor-3β (HNF-3β)?

Back 66

maintains primitive node and necessary for forebrain and midbrain differentiation.

Front 67

What does FGF-8 do?

Back 67

induces expression of Nodal and Lefty2 genes on left side of embryo. Results in upregulation of PITX which establishes left side of embryo.

Front 68

What is function of Lefty-1?

Back 68

expressed from left side floor plate of neural tube and acts as a barrier preventing left-sided factors going to right side. Sonic Hedgehog (Shh) has similar function and suppresses left-sided genes on the right. Shh is expressed from the notochord.

Front 69

What does Snail do?

Back 69

downstream regulation of genes determining right side development.

Front 70

What is Polyhydramnios?

Back 70

Excess of amniotic fluid resulting in anencephalia, gastrointestinal atresia, and diabetes.

Front 71

What is Oligohydramnios?

Back 71

A defiency in amniotic fluid that results renal atresia, hypoplasia, or polycystic kidneys.

Front 72

What are the Functions of Amniotic Fluid?

Back 72

Symmetrical growth
Prevents adherence of amnion
Maintenance of constant temperature
Prevents mechanical trauma
Allows for movement
Fluid wedge at parturition
Estimation of fetal maturity

Front 73

General characteristics of the Yolk Sac

Back 73

Does not contain yolk in human embryos.
Is the first site of hematopoiesis(embyonic wave) and may produce serum proteins
Gives rise to germ cells that later populate the gonads
May have a limited role in early metabolism.
Disappears before birth or may persist as a Meckel’s diverticulum.( It is a true congenital diverticulum,a small bulge in the small intestine present at birth. It is a vestigial remnant of the omphalomesenteric duct (also called the vitelline duct or yolk stalk), and is the most frequent malformation of the gastrointestinal tract. It is present in approximately 2% of the population,with males more frequently experiencing symptoms)

Front 74

What are the functions of yolk sac?

Back 74

First site of hematopoiesis (embryonic wave) and serum protein production.
Site of primordial germ cell differentiation.

Front 75

What is Allantois?

Back 75

Develops from wall of yolk sac (16th day).
Rudimentary in humans.
May have a role in induction of vitelline and umbilical vessels.
Persists in the adult as the urachus (median umbilical ligament) which extends from the bladder to the midline of the anterior abdominal wall.

Front 76

What are derivatives of ectoderm?

Back 76

CNS,PNS(autonomic and parasympathetic), DRG, sensory epithelium(ear, eye, nose), epidermis of skin(hair, nails, sweat glands, mammary glands, pituitary gland, enamel of teeth

Front 77

What are derivatives of mesoderm?

Back 77

supporting tissues(connective, cartilage, bone), muscle(striated, smooth), blood and lymph, heart, blood and lymph vessel walls,kidney, gonads, suprarenal gland cortex, spleen

Front 78

What are derivatives of endoderm?

Back 78

lining of gut and parenchyma of associated organs(liver, gall bladder, pancreas), lining of respiratory system, lining of urinary bladder, parenchyma of thyroid and parathyroids, lining of tympanic cavity and auditory tube

Front 79

How is BMP4 involved in formation of neural plate?

Back 79

The blocking of BMP4 expression will result in the formation of the neural plate in the midportion of the ectoderm

Front 80

What is function of Shh in neural tube regulation

Back 80

Shh Signaling initiates invagination of the neural plate into the embryo

Front 81

What do noggin, chordin, and follistatin do in neural tube regulation?

Back 81

inactivate BMP-4 causing ectoderm to become neutralized(neural plate-forebrain and ectoderm)

Front 82

What is function of WNT-3 and FGF in regulation of neural tube?

Back 82

needed to allow induction of caudal neural plate to form hindbrain and spinal cord

Front 83

What do BMP's do?

Back 83

regulate PAX's expression in the dorsal neural tube that will form the roof plate and alar plate

Front 84

What are three primary vesicles formed from the cranial portion of the neural tube?

Back 84

Forebrain(prosencephalon), midbrain(mesencephalon), and hindbrain(rhombencephalon)

Front 85

What are 5 secondary vesicles formed from the cranial portion of the neural tube?

Back 85

telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon

Front 86

What is telencephalon and what primary vesicle is it derived from?

Back 86

cerebral hemispheres from the forebrain(prosencephalon)

Front 87

What is diencephalon and what primary vesicle is it derived from?

Back 87

thalami and derived from the forebrain (prosencephalon)

Front 88

What is mesencephalon and what primary vesicle is it derived from?

Back 88

midbrain derived from the mesencephalon

Front 89

What is metencephalon and what primary vesicle is it derived from?

Back 89

pons and cerebellum derived from the metencephalon and metencephalon are from the rhombocephalon(hindbrain)

Front 90

What is myelencephalon and what primary vesicle is it derived from?

Back 90

medulla derived from the myelencephalon. myelencephalon is from the rhombocepahlon(hindbrain)

Front 91

What is formed from the caudal portion of the neural tube?

Back 91

the spinal cord

Front 92

What do neuroepithelial cells become?

Back 92

neuroblasts, astrocytes, oligodroglia, ependymal cells,neurons

Front 93

Neuroblasts form the mantle layer which becomes what?

Back 93

gray matter

Front 94

What layer are microglial cells derived from?

Back 94

mesoderm

Front 95

What do neuroepithelial cells that line the cavity of the neural tube become?

Back 95

ependymal cells of the ventricle and spinal canal

Front 96

Neuroblasts differentiate into neurons and extend processes to the periphery of the neural tube. As the processes become myelinated this layer becomes known as____

Back 96

marginal layer which is white matter

Front 97

What are the positional changes of the spinal cord?

Back 97

initially spinal cord extends length of embryo, dura and vertebrae grow faster than spinal cord.
At birth end of cord(conus medullaris) is at L3 level
Cord ends between L2-L3 level in the adult

Front 98

What is spina bifida occulta?

Back 98

the outer part of some of the vertebrae are not completely closed.The split in the vertebrae is so small that the spinal cord does not protrude. The skin at the site of the lesion may be normal, or it may have some hair growing from it; there may be a dimple in the skin, a lipoma, a dermal sinus or a birthmark.[3]

Front 99

What is spina bifida cystica?

Back 99

a cyst protrudes through the defect in the vertebral arch. These conditions can be diagnosed in utero on the basis of elevated levels of alpha-fetoprotein, after amniocentesis, and by ultrasound imaging. Spina bifida cystica may result in hydrocephalus and neurological deficits

Front 100

What are the positional changes of the spinal cord?

Back 100

initially spinal cord extends length of embryo, dura and vertebrae grow faster than spinal cord.
At birth end of cord(conus medullaris) is at L3 level
Cord ends between L2-L3 level in the adult

Front 101

What are derivatives of the neural crest?

Back 101

spinal ganglia(dorsal root), schwann cells(neurilemma), sympathetic ganglia, leptomeninges(pia and arachnoid), melanocytes, odontoblast(dentin of teeth), head mesoderm-pharyngeal arches, suprarenal medulla, heart(septum)

Front 102

What are the positional changes of the spinal cord?

Back 102

initially spinal cord extends length of embryo, dura and vertebrae grow faster than spinal cord.At birth end of cord(conus medullaris) is at L3 level Cord ends between L2-L3 level in the adult

Front 103

What is spina bifida?

Back 103

It results from vertebral rachischisis(lack of fusion).It is a developmental birth defect caused by the incomplete closure of the embryonic neural tube. Some vertebrae overlying the spinal cord are not fully formed and remain unfused and open. If the opening is large enough, this allows a portion of the spinal cord to protrude through the opening in the bones. There may or may not be a fluid-filled sac surrounding the spinal cord. Other neural tube defects include anencephaly, a condition in which the portion of the neural tube which will become the cerebrum does not close, and encephalocele, which results when other parts of the brain remain unfused.

Front 104

What is spina bifida occulta?

Back 104

the outer part of some of the vertebrae are not completely closed.The split in the vertebrae is so small that the spinal cord does not protrude. The skin at the site of the lesion may be normal, or it may have some hair growing from it; there may be a dimple in the skin, a lipoma, a dermal sinus or a birthmark.[3]

Front 105

What is Arnold-Chiari malformation?

Back 105

herniation of cerebellum due to tethering of cord in spina bifida cystica

Front 106

What is spina bifida cystica meningocele?

Back 106

The least common form of spina bifida is a posterior meningocele (or meningeal cyst).
In a posterior meningocele, the vertebrae develop normally, however the meninges are forced into the gaps between the vertebrae. As the nervous system remains undamaged, individuals with meningocele are unlikely to suffer long-term health problems, although there are reports of tethered cord.

Front 107

What is spina bifida cystica meningomyelocele?

Back 107

the most serious and common form. The unfused portion of the spinal column allows the spinal cord to protrude through an opening. The meningeal membranes that cover the spinal cord form a sac enclosing the spinal elements.

Front 108

What is hydrocephalus?

Back 108

This condition results from aqueductal stenosis or tethering of neural tube derivatives forming the spinal cord.

Front 109

What is cranium bifida?

Back 109

ossification defect of the skull

Front 110

What is cranium bifida meningocele?

Back 110

see notes

Front 111

What is cranium bifida meningoencephalocele ?

Back 111

see notes

Front 112

What is cranium bifida meningohydroencephalocele?

Back 112

see notes

Front 113

What is exencephaly?

Back 113

the cranial neural tube failed to close

Front 114

What is craniorachischisis?

Back 114

the skull failed to completely form

Front 115

What is anencephaly?

Back 115

a cephalic disorder that results from a neural tube defect that occurs when the cephalic (head) end of the neural tube fails to close, usually between the 23rd and 26th day of pregnancy, resulting in the absence of a major portion of the brain, skull, and scalp. Results from exencephaly and cranioachischisis. Most of the caudal neural failed to close as well resulting in myeloschisis(Cleft spinal cord resulting from failure of the neural folds to close normally in the formation of the neural tube) and vertebral rachischisis(the neural tube fails to close completely. The vertebrae overlying the open portion of the spinal cord do not fully form and remain unfused and open. Thus, the spinal cord is exposed).

Front 116

Formation of the pituitary gland(the hypohysis) includes....

Back 116

Rathke's pouch and infudibulum

Front 117

What is derived from Rathke's pouch?

Back 117

adenohyphosis, pars tuberalis, and pars intermedia

Front 118

What is derived from Infundibulum?

Back 118

stalk and pars nervosa

Front 119

Some cranial nerve facts

Back 119

all cranial nerves except olfactory(I), optic(II) and spinal assessory(XI) arise form brainstem and all that arise from the brainstem do so from the rhombencephalon except for the oculomotor(III) and trochlear(IV) which arise form the mesencephalon

Front 120

Molecular signaling from the occipital somites influence development of the__________.

Back 120

rhombencephalon (hindbrain).

Front 121

The rhombencephalon gives rise to motor nuclei of what cranial nerves?

Back 121

cranial nerves V, VI, VII, IX, X, XII.

Front 122

What do Ectodermal placodes do?

Back 122

form from surface ectoderm and move into the embryo and then are populated by neural crest cells which form neurons of the sensory ganglia of cranial nerves.

Front 123

Near the 17th day the_________ mesoderm is established and cells proliferate near to midline forming the________ mesoderm

Back 123

intraembryonic

paraxial

Front 124

The lateral plate mesoderm will ultimately split into what 2 membranes?

Back 124

somatic or parietal mesoderm and the splanchnic or viscersal mesoderm

Front 125

The space formed by the splitting of the lateral plate mesoderm is called the____________.

Back 125

intraembryonic coelom

Front 126

The somites differentiate into the________and the __________.

Back 126

Sclerotome and Dermomyotome

Front 127

The sclerotome forms the_______and the dermomyotome forms the ______and the _________.

Back 127

vertebral column
myotome(segmental muscalature)
and dermatome(segmental skin component)

Front 128

What does the skeletal system develop from?

Back 128

the paraxial mesoderm, lateral plate mesoderm and neural crest

Front 129

Cells of the sclerotome proliferate and form what tissue?

Back 129

mesenchyme(embryonic connective tissue)

Front 130

Mesenchyme is pluripotent and is able to differentiate into?

Back 130

fibroblasts, chondroblasts and osteoblasts

Front 131

What is intramembraneous ossification?

Back 131

Cartilage is not present during intramembranous ossification. It is also an essential process during the natural healing of bone fractures and the rudimentary formation of bones of the head.

Front 132

What is endochondral ossification?

Back 132

Cartilage is present during endochondral ossification. It is also an essential process during the rudimentary formation of long bones,the growth of the length of long bones, and the natural healing of bone fractures.

Front 133

What is the membraneous neurocranium?

Back 133

It forms the vault around the brain and is derived form neural crest and paraxial mesoderm

Front 134

What are flat bones derived from?

Back 134

primary ossification centers form within the mesenchyme and give rise to flat bones by membranous ossifications

Front 135

What are the plates of developing bones separated by?

Back 135

very wide sutures called fontanelles

Front 136

What is the prechordal chonrocranium formed from?

Back 136

the neural crest---body of sphenoid and body of ethmoid

Front 137

What is the chordal chondrocranium formed from?

Back 137

the paraxial mesoderm

Front 138

What is formed from the mesenchymal condensations?

Back 138

lesser and greater wings of sphenoid and mastoid and petrous parts of temporal bone

Front 139

What does the viscerocranium consist of ?

Back 139

bones of face and formed from first two pharyngeal arches

Front 140

What are first arch dorsal components?

Back 140

maxilla, zygomatic bone, squamous portion of temporal bone, malleus and incus

Front 141

What are first arch ventral components?

Back 141

mandible

Front 142

What are the second arch components?

Back 142

styloid process, upperpart of the hyoid bone and stapes

Front 143

What is cranioschisis?

Back 143

the cranium fails to close completely (especially at the occipital region). Thus, the brain gets exposed to the amnios, and eventually degenerates,causing anencephaly

Front 144

What is encephalocele?

Back 144

a neural tube defect characterized by sac-like protrusions of the brain and the membranes that cover it through openings in the skull. These defects are caused by failure of the neural tube to close completely during fetal development. Encephaloceles cause a groove down the middle of the skull, or between the forehead and nose, or on the back side of the skull

Front 145

What is craniosynotosis?

Back 145

a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses. This results in restricted skull and brain growth. Because the brain cannot expand in the direction of the fused suture, it is forced to grow in the direction of the open sutures, often resulting in an abnormal head shape and facial features.

Front 146

What is scapocephaly?

Back 146

early closure of saggital suture

Front 147

What is acrocephaly?

Back 147

early closure of coronal suture

Front 148

What is plagiocephaly?

Back 148

premature closure of coronal and lambdoid sutures on one side

Front 149

How is Apical Ectodermal Ridge(AER) formed?

Back 149

the formation of the AER is induced by BMP's h

Front 150

What is initial limb growth induced by?

Back 150

FGF-8

Front 151

What keeps the process of limb growth going?

Back 151

FGF-4

Front 152

Characteristics of craniocaudal development

Back 152

cells forming zone of polarizing activity(ZPA) produce retinoic acid(vitamin A) which initiates Shh expression. This is responsible for craniocaudal patterning of the limb

Front 153

In the hand the stronger signal(posterior) causes digit 5(the little finger to develop while the weaker signal(anterior) causes_____

Back 153

formation of digit 1(thumb)

Front 154

What causes cell death(apoptosis) in hand and foot plates resulting in loss of tissue separating finger and toes?

Back 154

BMP-4W

Front 155

What is involved in dorsoventral development?

Back 155

Wnt7a is limited to the dorsal ectoderm of the limb bud and is regulated by the homeobox LMX1
If the dorsal ectoderm is removed then that side of the arm will ventralize--so the palm area skin will be reproduced on back of hand

Front 156

What initiates limb bud growth?

Back 156

FGF-8

Front 157

What maintains limb growth?

Back 157

FGF-4

Front 158

What is responsible for regional differentiation of bones?

Back 158

HOXD genes 9-13

Front 159

When does limb rotation occur?

Back 159

the 7th week

Front 160

What is meromelia and amelia?

Back 160

partial and complete abscence of limb

Front 161

What is polydactyly?

Back 161

too many digits

Front 162

What is ectrodactyly?

Back 162

absence of one or more digits

Front 163

What is syndactyly?

Back 163

fusion of digits

Front 164

What occurs during the 4th week of development with sclerotomes?

Back 164

the schlerotomes of the segmental somites surround the notochord and neural tube. Dorsal portions form vertebral(neural) arches and ventral portions form vertebral bodies

Front 165

4 steps involved involved in formation of vertebral column?

Back 165

see handoutq

Front 166

Skeletal, smooth and cardiac muscle develop from?

Back 166

mesoderm--skeletal mesoderm develops from paraxial mesoderm and smooth and cardiac muscle from splanchnic mesoderm

Front 167

What does epimere do?

Back 167

gives rise to deep intrinsic extensor muscles of the back--innervated by dorsal primary rami and are epaxial

Front 168

What does hypomere do?

Back 168

gives rise to lateral and ventral flexor muscles--innervated by ventral primary rami and are hypaxial