A liquor contacting area in the pineal recess of the golden hamster (Mesocricetus auratus).

The wall of the third ventricle in the pineal recess of the golden hamster (Mesocricetus auratus) has been investigated by light and electron microscopy. Deep in the pineal recess, where the ependymal lining is thin and non-ciliated, clusters of pinealocytes protrude into the ventricular lumen. They force the ependyma apart so that their surface is directly exposed to the CSF, while basal processes extend towards the hypependymal pineal tissue. It is assumed that these cells may secrete melatonin into the CSF which is known to contain varying amounts of this hormone.