9. Development of the nose (workbook) Flashcards
what is the first evidence of the nose formation?
appearance of 2 ectodermal thickenings (nasal placodes) either side of the midline, on the ventrolateral aspect of the frontonasal prominence
what is a placode?
the name given to an area of ectoderm that starts to thicken and differentiate itself from its surrounding tissue to give rise to sensory structures
what is the otic placode?
from which the future ear develops
what happens to the nasal placode?
invaginate and form deep pits (nasal pits)
what forms the future nostril?
the entrance of each nasal pit
what forms around the entrance to each nostril (entrance to nasal pit)?
a horseshoe-shaped ridge
what are the ‘arms’ of the horseshoe-shaped ridge forming around the entrance to each nostril?
medial and lateral nasal prominences (processes)
where do the deepening nasal pits lie?
dorsal to the stomodaeum
what separates nasal pit from stomodaeum? called?
by a thin sheet of cells (oronasal membrane) - separates the oral and nasal cavity
what happens to the oronasal membrane separating each nasal pit?
it disappears, oral and nasal cavities become one continuous space
what then separates the oral and nasal cavity when the oronasal membrane disappears?
development of the palate
what does the palate development involve?
involves the maxillary prominences and the medial nasal prominences
how does the palate develop from the maxillary prominence and the medial nasal prominence?
the medial nasal prominences merge in the midline, separating the nostrils form the mouth and form the philtrum of the upper lip and a small midline component of the palate
what is the philtrum of the upper lip and a small midline component of the palate known as?
primary palate / premaxillary portion
what grows from each maxillary prominence?
a palatal shelf grows from each maxillary prominence towards the midline
