Which of the following develop from somites?
Axial skeleton
Appendicular skeleton
Axial muscles
Appendicular muscles
What is found in the centre of the developing embryo?
Neural tube
Pairs of somites
Limb buds
Notochord
Sclerodome
Somites develop in pairs. True or false?
From which end do the pairs of somites develop?
Caudal end
Rostral end
Superior end
Inferior end
What is somite development controlled by?
A chemical gradient
The mother's hormonal levels
Which genes a switched on or off in each cell
Somites account for only a small amount of our body mass after development. True or false?
Which of the following are developed from the somites?
Dermatome
Myotome
Sclerotome
Syndetome
Heptatome
Angiotome
What does the skin develop from?
What does muscle develop from?
Scleratome
What does bone develop from?
What do ligaments and tendons develop from?
What do somites induce?
Spinal nerve formation
Cranial nerve formation
Afferent neurone formation
Efferent neurone formation
How are vertebrae formed from the somites?
From the caudal end of one somite and the cranial end of another
One somite goes onto create one vertebra
Two somites fuse across the neural tube to form a vertebral bone
Somites do not go onto form vertebrae
Which part of the somite is split into two by the development of the spinal nerve?
The scleratome of the first five somites goes onto create which bone?
Occipital bone
Frontal bone
Temporal bone
Sphenoid bone
Parietal bone
The scleratome converges around the neural tube. True or false?
If the scleratome does not converge around the spinal cord completely what condition will the child have?
Spina bifida
Pattau's syndrome
Scoliosis
Brevicollis
Kyphosis
Where in the developing embryo will the notochord be found?
In the neural tube
Between the first and second somites
In the scleratome
In the developing spinal nerves
Most of the notochord is removed during development, but it remains in one place. Where does it remain?
Nucleus pulposis of the intervertebral disc
Annulus fibrosis of the intervertebral disc
In the dorsal root ganglion of spinal nerves
In the lining of the ventral median fissure of the spinal cord
What is scoliosis?
Lateral curvature of the spine
Reduced number of cervical vertebrae
Reduced number of thoracic vertebrae
Dorsal displacement of the spine
What is brevicollis?
Lumbar vertebrae of abnormally small size
Absence of a sacral bone
What do limb buds develop from?
Lateral mesoderm and over-lying ectoderm
Medical mesoderm and ectoderm
Mesoderm and the ectoderm that is deep to it
Mesoderm only
What are limb buds controlled by?
HOX genes
House-keeping genes
Chemical gradients
Somites
What develops from the limb buds?
What are the three stages in limb bud development?
Initiation
Limb bud patterning
Digit patterning and sculpting
Elongation
Sclerotome division
During limb bud patterning of the upper limb, which bone will develop first?
Carpals
Ulna
Humerus
Scapula
What does digit patterning involve?
Apoptosis of cells at the end of the limb bud
Coordinated outgrowth of cells to form digits
Necrosis of webbing between the newly developed digits
What are the names of the two signalling centres on the limb buds?
Apical ectodermal ridge (AER)
Zone of polarising activity (ZPA)
Basal mesodermal dome (BMD)
Sclerotome signalling centre (SSC)
Which of the following is produced by the apical ectodermal ridge (AER)?
FGF8
SHH
Sonic hedgehog
What is the function of the signalling molecules produced by the AER and the ZPA?
Ensure the correct bones develop in the correct place
Ensure that apoptosis occurs where it is needed to
Ensure that the limb bud reaches it's full length
Ensure that any mutated cells are destroyed
Ensure that the limb bud develops in the correct direction by creating a chemical gradient
What is the function of FGF8 from the apical ectodermal ridge (AER)?
Maintain proliferation in the progress zone
Prevent cell division anywhere other than the progress zone
Turn of proliferation in the progress zone when new cells are no longer required
What chemical signal controls the apoptosis that creates the fingers and the toes?
BMP
What will occur when apoptosis of the end of the limb bud does not occur?
Syndactayly
Meromelia
Cleft hand or foot
What condition is BMP related to where the receptors are activated when BMP is not present?
Fibrodysplasia ossificans progressiva
Osteoarthritis
Rheumatoid arthritis
Ankalyosis spondylitis
What happens in fibrodysplasia ossificans progressivia?
Tissues become progressively ossified when they shouldn't be
The ossification of tissues is progressively broken down
The body has an inflammatory reaction to tissue that are ossified
What is amelia?
The congenital absence of one or more limbs
The congenital absence of a part, but not all, of one or more limbs but with the presence of a hand or foot
A congenital deformity in which the hand or feet are closely attached to the torso with the limbs being under-developed
What is meromelia?
Congenital absence of one or more limbs
Congenital absence of a part, but not all, of one or more limbs but with the presence of a hand or foot
A congenital deformity in which the hands or feet are closely attached to the torso, with the limbs being under-developed
What is phocomelia?
The congenital absence of a part, but not all, of one or more limbs, but with the presence of a hand or foot
What drug is famously known to cause amelia, meromelia and phocomelia?
Thalidomide
Methotrexate
Dexamethosone
Enalapril
Aspirin
What is ectrodactyly?
Congenital absence of part or all of one or more fingers or toes
A condition in which a person has more than five fingers or toes on one, or each, of their hands or feet
A condition of having some or all of the fingers or toes partly or wholly united
All the normal elements of a limb are present in club foot or club hand. True or false?
Why are the dermatomes in an adult human rotated?
Because of limb rotation that occurs during development
Because of limb rotation that occurs after birth
Because we a bipedal, not quadrupedal
Because the spinal nerve rotate during development
What condition affects one dermatome of skin?
Shingles
Menigitis
Pityriasis rosea
Bell's palsy
Chicken pox
Why does shingles only affect one dermatome?
Because the virus travels down one spinal nerve only
Because the immune cells in this area of skin have been destroyed
Because the virus is only present on the skin in this dermatome
What does the myotome go onto form?
Epimere
Hypomere
Ectomere
Mesomere
Hypermere
The limb muscles develop from the...?
What does the epimere develop into?
Dorsal muscles - i.e. muscles of the back
Limb muscles - i.e. flexors and extensors
Ventral muscles - i.e everything but the muscles of the back
Which of the following is bigger?
What goes onto supplies the muscles formed from the epimere?
Dorsal ramus of the spinal nerve
Ventral ramus of the spinal nerve
Sympathetic chain
Cranial nerves IX - XI
What controls somite division?
Signalling molecules produced by adjacent tissues
Signalling molecules produced by the neural tube
Signalling molecule produces by the notocord
Signalling molecules in the embryonic fluid
Hormones produced by the mother
What do myogenic factors do?
Drive skeletal muscle-specific differentiation
Create a chemical gradient to direct muscle growth in the correct direction
Prevent abnormal muscle growth
Myogenic factors remain present after development. True or false?
What is the function of myogenic factors after development?
Set aside stem cells for muscle repair
Prevent striation from being lost from the skeletal muscle
Signalling molecule BMP is also important in the attachment of the syndetome to bone and muscle so it can form tendons. True or false?
What are the name of the stem cells within mature skeletal muscle?
Satellite cells
Basal cells
Myogenic repair cells
What neurotransmitter is present at the neuromuscular junction?
Acetylcholine
Dopamine
Noradrenaline
GABA