from The Century Dictionary.
- Same as
from the GNU version of the Collaborative International Dictionary of English.
- adjective (Biol.) Relating to the entoderm.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- adjective biology Relating to the
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The ventral end of the entodermal wall is fused with the wall of a small cavity, _li_, which may be traced several sections cephalad to this plane.
These lymphoid cells are probably derivatives of the entodermal cells which lined the original diverticula and their subdivisions.
The intervening mesoderm is pressed aside and the ectoderm comes for a time into contact with the entodermal lining of the fore-gut, and the two layers unite along the floors of the grooves to form thin closing membranes between the fore-gut and the exterior.
From the third pharyngeal pouch the thymus arises as an entodermal diverticulum on either side, and from the fourth pouches small diverticula project and become incorporated with the thymus, but in man these diverticula probably never form true thymus tissue.
The endothelial lining of the heart and blood-vessels and the blood corpuscles are, however, regarded by some as being of entodermal origin.
The thymus appears in the form of two flask-shaped entodermal diverticula, which arise, one on either side, from the third branchial pouch (Fig. 1175), and extend lateralward and backward into the surrounding mesoderm in front of the ventral aortæ.
The bladder is formed partly from the entodermal cloaca and partly from the ends of the Wolffian ducts; the allantois takes no share in its formation.
This bend becomes dilated into a pouch, which constitutes the entodermal cloaca; into its dorsal part the hind-gut opens, and from its ventral part the allantois passes forward.
The entodermal lining of the dorsal end of this pouch is in contact with the ectoderm of the corresponding pharyngeal groove; by the extension of the mesoderm between these two layers the tympanic membrane is formed.
The entodermal cloaca is divided into a dorsal and a ventral part by means of a partition, the urorectal septum (Fig. 992), which grows downward from the ridge separating the allantoic from the cloacal opening of the intestine and ultimately fuses with the cloacal membrane and divides it into an anal and a urogenital part.