Medicine and Health related Information

Embryological subdivisions of palate and lines of fusion:– From each maxillar process a plate like shelf grows medially. This is called the palatal process.
The palate is formed from the three components:- They are
a) The two palatal processes and
b) The primitive palate formed from the frontonasal process. The definitive palate is formed by the fusion of these three parts as follows –
1) Each palatal process fuses with the posterior margin of the primitive palate.
2) The two palatal processes fuse with each other in the mid line. Their fusion begins anteriorly and proceeds backwards.
3) The medial edge of the nasal septum thus seperating the two nasal cavities from each other and from the mouth.
At a later stage the mesoderm in the palate undergoes intramembranous ossification to form hard palate. Ossification does not extend into the posterior most portion which remains as the soft palate. The part of the palate derived from the frontonasal process forms the premaxilla which carries incisor teeth.

CLEFT PALATE:– In this condition the mouth and nasal cavities communicate with one another. It is because of the union of palatal process with one another and with primitive palate on one side or both the side. This is usually associated with hare lip.

NEURAL CREST CELLS:– At the junction of surface ectoderm and the neuro ectoderm, few cells are deattached and form the neural crest cells and are present on either side of the neural tubulae which give rise to:–
a) Dorsal root ganglion of all spinal nerves.
b) Pseudo unipolar neurons of trigeminal ganglion of 7th,9th and 10th cranial nerves.
c) Leptomeninges – pia and arachnoid matter together they develop from the neural crest cells.
d) Schwann cells – of the peripheral nervous system.
e) Neurons of sympathetic ganglion.
f) Ameloblast cells
g) Melanocyte pigment of the skin
h) Bronchial cartilage cells
i) Medulla of adrenal gland
j) Chromoffin system
k) Bipolar neurons of auditory nerves
l) Head mesenchyme cells.