The umbilical cord normally contains two arteries (umbilical arteries) and one vein (umbilical vein) embedded within connective tissue named Wharton's jelly.
Mucoid connective tissue (or Wharton's jelly) is a gelatinous substance that is mostly ground substance (primarily hyaluronic acid and chondroitin sulfate) with a low abundance of collagen or reticular fibers.
Near the remnant of the allantois are many stellate and spindle-shaped (fusiform) cells. Most of these are mesenchymal cells. However, spindle-shaped mesenchymal cells are indistinguishable from resting fibroblasts (which also may be spindle-shaped).