What embryological problem might you suspect in someone who has a deformity in their limbs?
Apical ectodermal ridge. It secretes FGF to promote mesenchymal cell development into limb tissues.
What embryonic problem might you suspect in someone with webbed fingers?
What do somites develop into?
Dermatomes, myotomes, sclerotomes and endothelia.
Where do somites come from?
Somitomeres that develop from the paraxial mesoderm
What structures will the dermatome, myotome and sclerotome eventually form?
Dermatome: skin on back Myotome: Muscle on back Scleotome: vertebrae and rib cage
Describe how endochondral bone formation progresses.
Mesenchyme cells form cartilaginous mass. Blood vessels invade and bring osteoblasts to center of diaphysis forming the primary ossification center. Chondrocytes migrate to epiphysis. Blood vessels invade epiphysis and secondary ossification centers form.
What anatomical portion of a somite will become muscle?
Epimere. It is the dorsal portion of a somite.
When your child is born, there are two main places you can ultrasound the brain. Which spot can you ultrasound for the longest period of time and which spot for the shortest?
Longest: Anterior fontanelle Shortest: Posterior fontanelle
How are flat bones formed?
Intramembranous ossification. Dense CT gives rise to osteoblasts. Osteoblasts lay matrix and form spongy bone. More osteoblasts around spongy bone form compact bone.
How does ossification differ in developing different locations of the skull?
Flat bones that surround the brain are derived from intramembranous ossification. The bones of the base of the skull are initially cartilaginous and form through endochondral ossification.
What portion of the skull is formed from the neural crest cells?
Membranous neurocranium and viscerocranium (face)
Why are geographically close portions of muscle and skin innervated by similar nerves?
In embryonic development, the dermatomyotome is derived from somites. Muscle and skin develop together.