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24 Hour Chick Embryo
At this level, sectioning has now reached the notochord. The notochord is
evident ventral to the neural folds. Ventral to the notochord, the foregut
appears as a smile-shaped cavity delimited by thin endodermally derived
walls. Note that the mid portion of the floor of the foregut is slightly
thickened. Below this region is a region of slightly thickened ectoderm. This
region is the oral plate which will become perforated at a later date to form
the mouth. Below the head fold is the subcephalic space and extra
embryonic germ layers. Note the proamnion (ectoderm and endoderm)
below the head fold. Lateral to the proamnion, layers of mesoderm are
visible between the ectoderm and endoderm. The cavity that is evident
1. Two subdivisions of Area Opeca i.e. Area Vitellina and Area Vasculosa
can be distinguished.
2. Hensen's Node is distinct.
3. There is no somite is present.
4. The clear head fold is anteriorly present.
5. Primitive streak is widened from posterior part.
6. Area Vasculosa is with traces of yolk.
7. At the cephalic region neural fold is present.