Ultrastructure of glial cells in the human fetal trigeminal ganglion.

In 9th and 10th week each neuroblast of trigeminal ganglion is surrounded by 2 satellite cells. The structure of Schwann cells is the same as satellite cells. With advancement of the development the number of satellite cells increases and at 23rd week on the periphery of neuron are 2-4 satellite cells. The myelination of nerve fibers starts at the 12th week. It has to be stressed that maturation of trigeminal ganglion precedes that of other cranial ganglia and spinal ganglia.