The majority of Teleosteans have thin flattened scales which differ from those of Ganoids in being entirely mesodermal in origin, containing no enamel.
The mesodermal coat of the optic stalk takes no part in this separation; it simply forms the connective tissue sheath of the optic nerve.
In some Annelids the central nervous system remains throughout life as part of the outer epidermis, but as a general rule it becomes separated from the epidermis and embedded in the mesodermal tissues.
Amphioxus, Balanoglossus and presumably Sagitta and the Brachiopoda, all the mesodermal tissues pass through the epithelial condition, most of the mesodermal tissues of the adult retaining this condition permanently.
Thus in many mammals the mesodermal part of the allantois often appears long before the endodermal part, though this is phylogenetically older.
The ectoderm of the anal fossa and the intestinal entoderm remain separated by a transverse mesodermal partition.
By migration and multiplication a large mass of mesodermal tissue is produced which fills the entire space between the mesothelium and the primary germ layers.
The mesodermal tissue which at this time attaches the alimentary tube along its entire extent to the dorsal wall of the coelom carries the primitive embryonic arterial vessel, the aorta.
Ectoderm and entoderm in this region with the intervening mesodermal layer form the cloacal membrane (Fig.
The new mesodermal cells thus produced constitute the mesenchyma, which includes the whole of the mesoderm of the embryo except the mesothelial lining of the coelom.
The mesodermal elements thus added to the enteric entodermal tube consist of connective tissue and muscular fibers.
Organs of the adult body, derived by budding from the alimentary entodermal epithelium, in the form of pouch-like diverticula which follow the glandular type of development and become secondarily associated with mesodermal elements.
This mesodermal tissue accompanies the duct in its further growth and branching, forming the connective tissue envelope, known in the adult as the capsule of Glison.
This latter, as well as the heart and the walls of the blood spaces, arises by the modification of mesodermal cells, and the body cavity is formed by the enlargement and coalescence of the blood channels and by the splitting of the fat body.
The paired oviducts and vasa deferentia are, as we have seen, mesodermal in origin.
The imaginal disks for the outer wall of the body, some of them, at any rate, include mesodermal rudiments (from which the muscles are developed) as well as hypodermis.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "mesodermal" in a variety of sentences. We hope that you will now be able to make sentences using this word.
