biochemical and haematological profile - Universitatea de Ştiinţe ...

Universitatea de Științe Agricole și Medicină Veterinară Iași
During the light period (at noon)
The pinealocytes became smaller in size , polyhedral in shape and the cytoplasm became
lighter in stain and non granular (Fig.9). The nuclei remain spherical, vesicular and eccentric
with a prominent nucleolus. The blood vessels became smaller in caliper and not engorged
with blood.
The pinealocytes appeared more electron lucent, free from secretory granules and the nucleus
became slightly irregular in outline. The profiles of the other organelles remained as the
previous stage (Fig.10).
By using the indirect immunohistochemical technique the pinealocytes showed a very faint or
slight reaction to the antimelatonin antibodies (Fig.11).
DISCUSSION
The epiphysis cerebri has a very interesting histological structure based on its unique
anatomical position. It is generally accepted that the pineal body develop as an upward
growth from the diencephalon to which it is connected by a short stalk (Ferreira‐Medeiros et
al. 2007 and Borregon et al. 1997).
The gland under investigation was covered by a thin fibrous capsule, the pia matter, from
which short septa penetrate the gland as mentioned by Hafeez (2005); Kus et al. (2004) and
Reus et al. (1990). The parenchymatous elements of the gland were supported by an extensive
network of reticular fibers (Borregon et al. 1997). Beside its role as a protective coat, the
fibrous stroma carry blood vessels, lymph and nerve supply of the gland (Kus etal. 2004).
There is a general agreement that the histological picture of the pineal parenchyma differs
according to light or dark period to which the individual exposed (Ferreira‐Medeiros et
al.2007; Kus et al. 2004 and Matsushima et al 1990). The authors stated that the gland
becomes well developed with a pronounced proliferation and activity of its parenchymal cells
during dark period while during light, the activity of the gland is greatly decreased. In this
respect, our study revealed that the pinealocytes of the glands collected during dark period
showed a marked proliferation as they become larger in size with finely granular cytoplasm
together with a marked congestion of the pineal blood vessels. The above mentioned
histological signs indicate a higher activity of the organ (Macchi and Bruce 2004). Moreover,
the pinealocytes showed a well developed rough endoplasmic reticulum, Golgi complex as
well as many mitochondria as mentioned by Ueck (1973) and Oksche et al. (1972). The authors
explained the role of each of these organelles in the secretory activity of the cell. The presence
of electron dense secretory granules as well as lipid droplets in the cytoplasm of pinealocytes
of buck at dark periods is an absolute sign of the increased secretory activity of the gland as
explained by Uria et al. (1992) and Owman and Rudeberg (1970). The pinealocytes of buck
showed long and branched cytoplasmic processes which either terminate in a flat dilatation
adjacent to blood capillaries or synapses with unmyelinated nerve. Similar observations were
also reported by Reuss et al. (1990) and Oksche et al. (1972). The latter explained the role of
cytoplasmic processes in the secretion on the other hand Mutsushima et al. (1990) explained
them as stimuli receivers. Both opinions could be met in the buck pineal where the
cytoplasmic processes joining blood capillaries play a role in secretion while that synapses with
nerve act as stimuli receivers.
The immunohistochemical reaction in our study augments the electron microscopic findings
and indicates that the buck pinealocytes produce considerable amount of melatonin during
darkness as stated by most researchers studying the pineal gland. Alexandr (1970) and Moore
et al. (1967) mentioned that the production of melatonin by the pineal gland is stimulated by
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