The size of the pineal gland is referred to as the VPP (volume of pineal "parenchyma"--term for pinealocyte
Even though the clear mechanism is unknown, a variety of physiological and degenerative changes might cause degeneration of pathways from retina to pineal gland, and/or reduction of pinealocyte
[beta]-adrenergic receptor functions may contribute to lowering plasma melatonin levels and this may lead to poor sleep quality .
The electron micrograph shows a large amount of premelanosomes (arrow) and melanosomes (m) within a pinealocyte
(p) and a pigmented cell (pg).
There is evidence that adrenalectomy in rats lead to significant increase in number of pinealocyte
processes and increase in melatonin forming enzyme hydroxy indoleomethyl transferase (HIOMT) which ultimately leads to an increase in pineal endocrine activity (Deuben-Schmitter et al., 1976).
Genetic variability in melatonin secretion originates in the number of pinealocytes
Biosynthesis of melatonin in pinealocytes
is a multistep sequence of reactions that starts with the hydroxylation of the amino acid tryptophan to 5-hydroxytryptophan (5-HTP) by the tryptophan hydroxylase (TPH).
An example of rat pineal gland and pinealocytes
(based on Ferreira-Medeiros et al., 2007): A--Morphometry, a stage micrometer was used to measure larger diameters (D1), and smaller diameters (D2) of pinealocytes
More recently, targeted gene deletion studies showed that NEUROD1 is required for the survival of photoreceptors, but not pinealocytes
, indicating a specific role for this gene in photoreceptors .
In animals, it is synthesized primarily by pinealocytes
of the pineal gland and regulates sleep and wakefulness.
Effect of superior cervical ganglionectomy on the ultrastructure of pinealocytes
in the Djungarian hamster (Phodopus sungorus): Quantitative study.
Two cells of interest in the brain-gut axis are pinealocytes
and enterochromaffin cells.
A 0.5 G, 60 Hz magnetic field suppresses melatonin production in pinealocytes
. Bioelectromagnetics 1998;19:123-7.