the present investigation was conducted on the pineal organs of 12 healthy bucks. Sixth
samples collected during dark period (at mid night) while the other six collected during light
period (at noon).The samples were processed and prepared for light and electron microscopic
examination. The pineal organ of bucks was surrounded by a thin fibrous capsule, the pia matter,
while the parenchyma was supported by extensive reticular network.The parenchyma of the
gland was formed of clusters or groups of pinealocytes intermingled with astroglia cells. Bundles
of unmyelinated nerve fibers were noticed in the organ. During dark period the pinealocytes
were large in size with finely granular cytoplasm containing well developed rER, mitochondria
and many secretory granules. Long branched cytoplasmic processes arised from the pinealocytes
to terminate near blood vessels or synapse with a nerve. The pinealocytes reacted positively with
antimelatonin antibodies. During the light period the pinealocytes appeared smaller in size with
clear non granular cytoplasm. The pinealocytes ahowed a very slight reaction to the
antimelatonin antibodies.