THE PINEAL ORGAN
IAMES CLARKE FENWICK
I. Introduction . . . . . . . . . . . . 91
11. The Pineal Dilemma . . . . . . . . . . 91
111. Ontogeny and Structure of the Pineal Organ .
. , . . 92
A. Ontogeny . . . . . . . . . . . .
92
B. Structure . . . . . . . . . . . . 93
C. Innervation
. . . . . . . . . . . 95
IV. Physiology of the Pineal Body . . . . . . . .
96
A. The Pineal Body as a Sensory Organ . . . . . . 97
B. The Pineal Body as a Secretory Organ . . . . . . 100
C. The Pineal Body as a Sensory cum Secretory Organ
. . 103
V. Synopsis
. . . . . . . . . . . . 103
References
. . . . . . . . . . . . . 104
I. INTRODUCTION
Despite the vast number of publications on the pineal body of fishes,
no distinct function has been unequivocally demonstrated. It is still
impossible to present a unified concept of pineal function; rather an
attempt will be made to review some of the evidence for the various
current hypotheses concerning its function. Several monographs on the
pineal body are available: StudniEka (1905), Tilney and Warren (1919),
Bargmann (1943), and Kitay and Altschule (1954); in addition, the
recently published proceedings of an international round-table conference on its structure and function, edited by Ariens Kappers and Schad6
(1965), contains many facts pertinent to the pineal body of fishes.
11. THE PINEAL DILEMMA
The most persistent question concerning the pineal gland of fishes
is whether it is the vestigial remnant of an ancestral third eye or whether
91