Animal experiments are conducted to demonstrate proof-of-concept and mechanisms of action, provide safe cell culture methods, carry out tissue engineering, and study infectious disease pathogenesis. Regarding the sustainable principles of the 3Rs, namely, refinement, reduction, and replacement, animal and human biological systems have been used. By definition, the Wharton's jelly (WJ) layer is a connective tissue localized in the middle of the umbilical vessels and amniotic epithelium. In this review, we would like to state that these cells belong to the division of primitive stromal cells. Because the WJ layer is an economical source of cells, the use of this resource would improve areas such as regenerative medicine, biotechnology, and agronomics worldwide in accordance with sustainability.