One form of connective tissue you don't see very often is mucous CT . This is a form of CT in which the matrix is the dominant component.
Fibers are very scanty.
Mucous CT is rare in adult vertebrates, as it's really an embryonic and fetal type. The object in the upper left corner of this field is one of the umbilical blood vessels. A smaller one lies next to it. As in other, more developed CTs, mucous CT is a route for the passage of blood vessels. These are lost after birth and the termination of the need for placental nutrition.