Third ventricular pineal gland grafts in the gerbil: An electron microscopical and immunohistochemical investigation

Abstract

The superficial pineal gland was grafted into the third ventricle of adult Mongolian gerbils. Donor pineal glands from both neonatal and 3-4 week old gerbils were able to survive for at least 6 months. The pinealocytes of the grafted superficial pineal glands maintained the morphology and the S-antigen immunoreactivity of the in situ pineal complex. Synaptic ribbons and spherules were present but rare. Unlike the in situ pinealocytes, glycogen accumulations were common in the graft pinealocytes. Site specific modulation of structure was indicated as the ventricular surface of the grafts became covered with cerebrospinal fluid (CSF)-contacting pinealocytes typical of those seen in the deep pineal. The CSF-contacting pinealocytes of the graft had numerous processes that extended along the ventricular surface of the graft. The blood vessels of the grafts had non-fenestrated endothelium and wide perivascular areas typical of those seen in the in situ pineal complex. Tyrosine hydroxylase-immunopositive nerve fibers were present in the grafted tissue indicating reinnervation of the graft. The source of the fibers was not determined. The nerve fibers were present both within the perivascular area and within the parenchyma where they were associated with pinealocytes. The results demonstrate that the cerebral ventricles are an ideal location for the survival of superficial pineal gland grafts. It is suggested that pineal grafts may be a means to further study pineal development and innervation.

Pineal Calcification, Melatonin Production, Aging, Associated Health Consequences and Rejuvenation of the Pineal Gland

“…To support this observation, more complicated studies have been performed in which pineal glands were transplanted into a variety of sites in pinealectomized rats. These sites included anterior chamber of the eye, third cerebral ventricle, the pineal region (in situ transplantation), intrastriatal, renal capsule and thymus [ 280 , 281 , 282 , 283 , 284 , 285 ]. The results indicated that in some cases the pineal gland transplantation did increase the melatonin levels in pinealectomized animals; however, except in the site of anterior chamber of the eye, no melatonin circadian rhythm was detected with the pineal gland transplantation and also the melatonin levels could not match those of the in situ pineal gland produced.…”

Actual problems of the cerebrospinal fluid-contacting neurons

“…In some mammals, the suprapineal recess and the central zone of the intrapineal recess contain pinealocytes that directly contact the CSF (Hewing, 1982;Welsh, 1983;Welsh and Li, 1992). The area of CSF-contacting pinealocytes of the intrapineal recess shows changes in size according to the circadian light periodicity (Welsh et.…”