Mucous connective tissue (or mucous tissue) is a type of connective tissue found during fetal development. It is composed mainly of ground substance with few cells or fibers. It can also be referred to a group of mucoproteins found in certain types of cysts (etc.), resembling mucus. It is most easily found as a component of Wharton's jelly.
Mucous connective tissue forms the umbilical cord.
It is sometimes considered equivalent to mesenchymal connective tissue.
The vitreous of the eyeball is a similar tissue.
References
Mucous connective tissue Wikipedia(Text) CC BY-SA