AP BIOLOGY

Detailed explanation-1: -The classical cell theory was proposed by Theodor Schwann in 1839. There are three parts to this theory. The first part states that all organisms are made of cells.

Detailed explanation-2: -In 1838, German scientist Matthias Schleiden concluded that all plants are made of cells. The next year Theodor Schwann, another German, concluded that all animals were also made of cells.

Detailed explanation-3: -His research led to the discovery of the cell that produces the myelin sheath that envelops the axon. In honor of his contribution, this was later eponymously named the Schwann cell [3, 7, 9]. He also found that during embryonic development individual cells unite to form the muscle fiber [10].

Detailed explanation-4: -By the late 1830s, botanist Matthias Schleiden and zoologist Theodor Schwann were studying tissues and proposed the unified cell theory. The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells.

Detailed explanation-5: -Schwann cells (SCs) are axon-ensheathing cells that naturally reside in the peripheral nervous system (PNS) of all vertebrate species.