Although the word chondroblast is commonly used to describe an immature chondrocyte, the term is imprecise, since the progenitor of chondrocytes (which are mesenchymal stem cells) can differentiate into various cell types, including osteoblasts
choanocyte. n. 1. (Zoology) any of the flagellated cells in sponges that maintain a flow of water through the body. A collar of protoplasm surrounds the base of the flagellum. Also called: collar cell.
Choanoflagellates are nearly identical to the collar cells (choanocytes) of sponges, which also act as filters of bacteria and food particles. One colonial species of Choanoflagellata in particular, Proterospongia, demonstrates some characteristics which may have been shared by some of the sponge's ancestors.