How did Theodor Schwann help establish the idea that cells are basic units of life?

Theodor Schwann was instrumental in establishing cell theory by extending the concept of the cell as a fundamental unit of life from plants to animals, effectively bridging the fields of botany and zoology.12

In 1839, Schwann published his seminal work, Microscopical Researches into the Accordance in the Structure and Growth of Animals and Plants, in which he and Matthias Jakob Schleiden clearly stated that cells are the "elementary particles of organisms" in both plants and animals. While Schleiden had previously proposed that plants are composed of cells, Schwann’s contribution was the critical realization that this principle applied universally to animal tissues as well.132

By comparing various animal and plant tissues, Schwann identified common cellular features, including the membrane, nucleus, and cell body. His work helped define the cell as the basic unit of animal structure, a foundation that remains central to modern histology and biological science.132