Skeletal Tissue: Development Flashcards
Bone formation occurs in these 2 ways
Intramembranous ossification (flat bone)
Endochondral ossification (weight bearing bones)
Type of bone formation that occurs for flat bones
Intramembranous ossification
Type of bone formation that occurs for weight-bearing bones like extremities and vertebrae-axial skeleton
Endochondral ossification
Type of bone formation:
Ossification without cartilage formation
Intramembranous
Type of bone formation:
Forms trabeculae resembling a sponge, also called spongy bone
Intramembranous
During Intramembranous ossification, osteoblast secretion of this leads to mineralization and osteocyte development
Calcium phosphate
Type of bone formation:
Bone matrix appears in histological sections as small, irregularly shaped spicules and trabeculae
Intramembranous
What occupies the spaces in between immature bone during intramembranous ossification?
Connective tissue and blood vessels
Type of bone formation that exists in pre-existing cartilaginous models
Endochondral ossification
This is the first sign of Endochondral ossification
The appearance of a cuff of bone around the cartilage model
The appearance of a cuff of bone around the cartilage model is the first sign of this type of bone formation
Endochondral ossification
Chondrocytes are derived from this
Perichondrial cells
Perichondrial cells give rise to this type of cell
Chondrocytes
A transverse disc of cartilage that remains due to the formation of the primary and secondary ossifications during endochondral ossification
Epiphyseal growth plate
This is the primary ossification center as a result of endochondral ossification
Diaphysis
This is the secondary ossification center as a result of endochondral ossification
Epiphysis
The cartilage of this is responsible for maintaining the growth process after endochondral ossification
Epiphyseal growth plate
During indirect healing after a fracture, these differentiate into periosteal cells, fibroblasts, or chondroblasts (cartilage) forming a soft callus
Osteoprogenitor cells
Type of bone healing where a blot clot of hematoma first forms at this site
Indirect healing
Smooth muscle is derived from this
Visceral splanchnic mesoderm
Mesodermal (mesenchymal) cells give rise to these long, spindle shaped cells that do not fuse and remain mononucleated
Myogenic cells / myoblasts
Ciliary muscle and sphincter pupillae of the eye are smooth muscle derived from this
Neural crest cells
Cardiac muscle is derived from this
Visceral splanchnic mesoderm that is found surrounding the heart tube
Cardiac myoblasts are derived from this
Mesenchyme
Skeletal muscle is derived from this
Paraxial mesoderm
Post-mitotic myoblasts begin to synthesize these 2 things
Actin and myosin
These form from myoblasts/myocytes and synthesize actin, myosin, troponin, tropomyosin and other muscle proteins
Myotubes / myofibers
Primary myogenesis occurs during this stage of development
Embryonic stage (up to 8 weeks)
Secondary myogenesis occurs during this stage of development
Fetal stage (8 weeks to birth)
At what week in development do mesenchymal cells of myotomes, as well as of specialized condensed (premuscle) areas of mesenchyme modulate into myoblasts, which begin to aggregate into syncytial tubes
4 weeks
At what week in development have syncytial myotubes formed primitive muscle fibers in which longitudinal myofilaments appear
Myotubes grow in length by incorporating additional myoblasts
5 weeks
At what week in development have more myofilaments appeared, but nuclei are still centralized
Growth in length continues through addition of myoblasts
9 weeks
Myotubes grow in length through addition of these
Myoblasts
These grow in length by addition of myoblasts
Myotubes
At what month in development have muscle fibers become thicker as myofilaments have multiplied and differentiated into thin (actin) and thick (myosin) myofilaments arranged in alternate overlapping bands, giving a cross-striated appearance
Nuclei move peripherally
Growth in length continues through addition of myoblasts
5 months
Are nuclei centralized or have they moved peripherally at 9 weeks development?
Still centralized
Are nuclei centralized or have they moved peripherally at 5 months of development?
Move peripherally
This arrests muscle growth when a muscle has attained its normal size
Myostatin
In the absence of this function, animals develop a grossly hypertrophic musculature
Myostatin
Myostatin arrests this
Muscle growth
(when a muscle has attained its normal size)
In the trunk region, each myotome partitions into these
A doral epimere and ventral hypomere
Partition of trunk myotome that develops into the extensor muscles of the neck and vertebral column
Epimere (epaxial)
Partition of trunk myotome that develops into the scalene, prevertebral, geniohyoid, infrahyoid, intercostal, abdominal muscles, lateral and ventral flexors of the vertebral column, quadratus lumborum, and pelvic diaphragm
Hypomere (hypaxial)
Myoblasts proliferate and exit the cell cycle to terminally differentiate to form this
Myocytes
These cells express contractile proteins such as actin and myosin and fuse to form myofibers, each of which consists of a multinucleated syncytium (i.e. a cellular mass with multiple nuclei) containing contractile myofibrils
Myocytes
Upper limb forms at this many days gestations
26
Lower limb forms at this many days gestations
28
Upper or lower limb:
Forms opposite of caudal cervical segments
Upper
Upper or lower limb:
Forms an apical ectodermal ridge (AER)
both
Upper or lower limb:
Rotates 90 degrees laterally
Upper
Upper or lower limb:
Forms opposite of the lumbar and upper sacral segments
Lower
Upper or lower limb:
Rotates 90 degrees medially
Lower
Major muscle mass that develops into the extensor and supinator musculature of the upper limb and the extensor and abductor musculature of the lower limb
Posterior condensation
Major muscle mass that develops into the flexor and pronator musculature of the upper limb and the flexor and adductor musculature of the lower limb
Anterior condensation
Each limb bud consists of a ______ core covered by a layer of ectoderm
Mesenchymal
Each limb bud consists of a mesenchymal core covered by a layer of this
ectoderm
This migrates into the limb bud to give rise to vasculature and skeletal formations
Lateral plate mesoderm
Limb buds elongate by proliferation of this
Mesenchyme
Chondrification centers form during this week of development
5th
Cartilaginous limbs form during this week of development
6th
Osteogenesis occurs in the limbs during this week of development
7th
Primary ossification centers form in limbs during this week of development
12th
This induces development of primordial phalanges
Apical epidermal ridge (AER)
Webbing of the fingers or toes
Syndactyly
Hand/foot plates form digital rays during this week of development
6/7th week
Digital rays form separate digits at this week of development
8th
Area of skin supplied by a single spinal nerve
Dermatome
Drug that was used to alleviate morning sickness in pregnant women
Has been linked to Phocomelia/Focomelia (reduced/missing arms and/or legs)
Thalidomide
Hyperextension and incurving of the feet
Occurs from abnormal positioning or restricted movement of the lower limbs of the fetus in utero (genetic and environmental factors together)
All anatomical structures are present
French (taping) method or Ponseti (casting) method
No discomfort or pain
Talipes Equinovarus
What is Talipes Equinovarus?
Hyperextension and incurving of the feet (clubfoot)
Occurs from abnormal positioning or restricted movement of the lower limbs of the fetus in utero (genetic and environmental factors together)
