松果体—その系統発生学的考察

The pineal organ: A phylogenetic concept

はじめに

　藤田（1977^5），1978^6））はパラニューロンの基準として次の3点を挙げている。

　基準I：神経分泌果粒様，ないし，シナプス小胞様の分泌果粒を持つ。

　基準II：神経分泌物，ないし，神経伝達物質と同一ないし関連する物質を産生する。

　基準III：特定の刺激を受容して，特定の分泌物質を放出する。

Abstract

　Characteristics of the pinealocytes as paraneurons, have been reviewed, with special references to their outer segments, synaptic vesicles, synaptic ribbons, and their core vesicles. Attention has also been paid to the nervous organization in pineal organs.

　The pinealocytes of lower vertebrates are photosensory cells. However, outer segments and synaptic vesicles are gradually lost in the phylogenetic development. Secretory granules which are usually seen in the pinealocytes of higher vertebrates, have also been reported in fish and amphibian pinealocytes.