During the late stages of development (around E15 - E18). the phagocytosis is too fast that the inactive, dying or dead cells (I. e., so-called light cells) are removed immediately as soon as they are formed so as not to leave such a light-cell stage for clear observation. The light-cell stage becomes clearly observable only when the phagocytic process is slow, and this becomes prominent at a time when some of the important connections are being actively established.
The fluctuation in the number of cells during embryonic development may be considered as a normal process for the purpose of re-arrangement and better organization to perform an orderly function most efficiently. The period of accelerated degeneration or loss of cells is the period of active establishment of proper connections of ganglion cells. The reduction or loss in the number of neurons in the adult ganglion might indicate a functional reduction probably as a result of aging process.
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