Right now, this is a 3 week old embryo in a uterus. The different colours represent the different germ layers the mesoderm, endoderm, and ectoderm. The allantois here is a way for embryo to excrete waste in the uterus.
The primitive gut tube is forming and now we can see the formation of the foregut, midgut and hindgut. The midgut is the primary point where the umbilical sac is going to get pinched off.
This is the transverse cut as labelled here. Here you can see the trilaminar disc. What is going to happen is that the yolk stalk is going to get pinched off. You will see the two arms are going to fuse and pinch off the yolk stalk to form the primitive gut. Here we go. The gut tube is held by the dorsal mesentery and we have the intraembryonic coelom surrounding the gut tube.
Development of the Foregut
So now we can see we have an embryo, there is a head and eye. Coming all the way down, this will be our future belly button, the allantois. The trachea is a deviation of the gut tube and will be discuss later by Kevin. We will now zoom in to the development of the stomach.
Development of the Stomach
This is the primitive gut tube seen in this transverse cut. Then we have the vagus nerves, the left and the right. The liver, dorsal and ventral mesentery. The stomach, we know rotates clockwise, because we find the left vagus nerves on top of the stomach and the right vagus nerve behind the stomach. The falciform ligament here is what connects the liver to the ventral mesentery. Now we will look at how the stomach from from the right side. Here is how the stomach is going to form into. The dorsal aspect of the stomach grows faster than the ventral aspect that’s why we have the greater curve and lesser curve of the stomach. So here it goes. Here is the esophagus coming in to the stomach, the greater curvature and lesser curvature, pylorus and duodenum. The greater omentum at the bottom is a two layer mesentery. The lesser ommentum is up here...
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