The pineal organ of the newt; a developmental study

Kelly, Douglas E.

doi:10.1007/bf00410657

Cited by 27 publications

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“…There is only equivocal evidence from this study that the pineal system in R. pipiens is involved in secretory activity. The hypothesis of Bagnara (1) that amphibian pineal organs are the source of melatonin, which is presumably responsible for the well known dark-induced blanching of pigment cells, awaits biochemical demonstration of a secretory product and its morphological correlates within amphibian pineal organs (reviewed elsewhere, 29,30). The first attempts to identify melatonin in amphibian pineal tissue by chemical means have yielded negative results (19).…”

Section: Discussionmentioning

confidence: 99%

FINE STRUCTURE OF THE PINEAL ORGANS OF THE ADULT FROG, RANA PIPIENS

Kelly

Smith

1964

The Journal of Cell Biology

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Frontal organs and epiphyses of the pineal system from the adult frog, Rana pipiens, were fixed in s-collidine-buffered osmium tetroxide, embedded in Epon 812, and examined by electron microscopy. Epiphyseal material was also fixed in a variety of ways and subjected to a series of cytochemical tests for light microscopy. An ultrastructure resembling that of lateral eye retina is confirmed in this species. Photoreceptor cells of the epiphysis and frontal organ display many cytological features similar to those of retinal rods and cones in the arrangement of their outer and inner segments and synaptic components. However, in these pineal organs the outer segments are disoriented relative to each other and may display a disarranged internal organization unlike normal retinal photoreceptors. Furthermore, other pineal outer segments often appear degenerate. Since immature stages in the development of new outer segments also appear to be present, adult pineal photoreceptors are probably engaged in a constant renewal of outer segment membranes. The evidence further suggests that maerophages are involved in phagocytosis of degenerated outer segments. Postulated photoreceptor activities and the possibility of secondary pineal functions, such as secretion, are discussed in view of current morphological and cytochemlcal findings.The presence of structures suggesting photoreceptire activity in pineal cells of cold-blooded vertebrates, earlier suspected on the basis of light microscopical studies, has now been confirmed for many organisms at the ultrastructural level.Eakin and Westfall (20, 21) and Steyn (51), working independently, were first to demonstrate stacks of lamellae, comparable to those of retinal rods and cones, in the outer segments of pineal sensory cells of the lizard parietal (parapineal) "eye." Later, the same investigators extended this finding to the sensory cells of the more deeply lying epiphyseal (pineal) component of the pineal system (17, 52). Both the frontal (parapineal) organ and the epiphysis have now been found to possess similar uhrastructure in tadpoles of the frog, Hyla regilla, (16,17,19,22) and in the adult frogs, Rana pipiens (29), Rana temporaria and Rana esculenta (41,42). We (31) have observed that presumed photoreceptor cells, well developed in the epiphyses of larval newts, Taricha torosa, are apparent to a lesser degree in adults of the same species. Moreover, since Eakin (18) has made a preliminary report of similar lamellated ciliary photoreceptors in the pineal apparatus of Ammocoetes larvae of lampreys, a concept of pineal morphology involving photoreceptive capability may well be valid for most lower vertebrates.

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Section: Discussionmentioning

confidence: 99%

FINE STRUCTURE OF THE PINEAL ORGANS OF THE ADULT FROG, RANA PIPIENS

Kelly

Smith

1964

The Journal of Cell Biology

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“…The pineal organ, which can act as a photoreceptor or can be influenced by some other photoreceptive structure (3,9), develops as an evagination of the dorsal wall of the diencephalon and remains attached to it by the pineal peduncle (8,10). Research in birds and mammals has implicated the pineal in the control of biological clocks and testicular recrudescence (11).…”

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confidence: 99%