Human motor end plate: some ultrastructural aspects of its development.

Regarding the motor end plates, the earliest evidence of the formation of such structures was observed in the muscle of foetuses of nine and ten weeks development. At this stage the developing motor end plate consits of several small axons covered on their outer aspect by Schwann cell cytoplasm, while on the inner aspect they are separated by a layer of basement membrane of the myotube with which they make contact. At this stage there is no evidence of secondary synaptic clefts but by the twenty eight weeks the motor end plate is similar to that seen in the adult.