Yolk stalk means: The yolk stalk is a narrow tube found in an embryo’s early stage that links the embryo’s midgut to its yolk sac. It can be seen through the umbilical opening. The yolk stalk becomes a nucleus later in the development process. However, a small remnant may remain, most often as a protrusion shaped like a finger from the small intestinale. Meckelis diverticulum can be found in between 2 and 4 percent of individuals. It may inflame much like an appendix, and need to be surgically removed. The omphalomesenteric, umbilical, and vitelline duct are all known.
(in Medical Dictionary)

What else does Yolk stalk mean?

An elongated, duct-like portion that links the yolk sac and the middle of an embryo’s digestive tract.
(in Merlin Dictionary)