Not before the skeleton or mesenchyme is formed in the sea urchin egg is the influence of the nucleus noticeable.
We leave the mesenchyme for a while and study another kind of organogenesis.
The mesenchyme ring, the coelum, the middle-intestine, are instances of such organs.
mesenchyme is the tissue which in Vertebrate embryology has frequently been called embryonic connective tissue.
The network of the spleen seems certainly to be derived from cells of the mesenchyme which lose their nuclei.
About thirty of the mesenchyme cells are occupied in the formation of skeleton substance on each side of the larva.
In the Vertebrata the whole of the mesoderm has at first the mesenchyme form.
In Echinodermata a certain amount of mesenchyme appears before the epithelial mesoderm, which is formed later as gut-diverticula.
mesenchyme mes·en·chyme (měz'ən-kīm', měs'-)
The part of the embryonic mesoderm that consists of loosely packed, unspecialized cells that are set in a gelatinous ground substance, from which connective tissue, bone, cartilage, and the circulatory and lymphatic systems develop.