the neuronal apparatus of the epiphysis cerebri of x. laevis consists of ( i ) photoreceptor cells , ( ii ) approximately 100 ache-positive neurons , ( iii ) complex neuropil areas , and ( iv ) a pineal tract formed by approximately 10 myelinated and approximately 100 unmyelinated nerve fibers .
C0027882
neurons
C0501409
unmyelinated nerve fibers