Arches Flashcards
What is the developmental relationship between the facial prominences and the pharyngeal arches?
The facial prominences and other structures specifically for the face usually develop from the first 2 pharyngeal arches.
Are there any facial prominences not associated with pharyngeal arches?
The lateral nasal prominence is not developed from a pharyngeal arch.
What are the major changes int he structure of the heart during development?
Sinus venosus (SV) moves from most caudal on the straight tube to being moved cranially and dorsally. Primitive atria moves cranially and dorsally - so moves towards head, behind the ventricles and gets divided into left and right. Primitive ventricle moves caudally and ventrally, in front of the atria. Internal interventricular septum forms to separate the two ventricles into left and right. Bulbus cordis (BC)is the most cranial portion of straight tube does not move during development but divide to form the pulmonary trunk and the aorta. Auricles derived from primitive atrium.
Why are there 3 circulatory circuits in the embryo? What is the function of each?
This is because ancestral animals developed a system by which the embryo could gain access to gases and nutrients and also maintain an intraembryonic circuit as well as producing a circuit which supplied the yolk sac (the placenta has taken its place here) and also developed a circuit to enter the allantois (this is also replaced by the placenta’s role), but regardless, the system has continued now too.
Intraembryonic circuit is still present to supply nutrients to various tissues around the body. Nutrients are supplied by the placenta.
The vitelline circuit functions to take blood vessels into the vitelline sac (yolk sac) and these vessels will eventually fuse to form the dorsal arteries of the mesentry of the gut.
Allantoic/umbilical circuit is the circuit which leads to the placenta and comes back from the placenta with nutrient and oxygen rich blood.
What germ layers contribute to the development of the face and throat?
It’s the neural crests (ectoderm) and mesodermal layers which contribute to the face and throat.
What will the frontonasal prominence be?
The future forehead.
What will the nasal placodes be?
They will sink in the inferior surface of the frontonasal prominence and become 2 pits that will become the nostrils.
How is the upper lip formed?
The medial nasal prominences fusing with the 2 maxillary prominences.
How is the lower lip and jaw formed?
The mandibular prominences that also grows towards the midline and eventually fuses.
