MICROVASCULARIZATION OF THE PINEAL-GLAND IN THE FRESH-WATER TURTLE, PSEUDEMYS-SCRIPTA ELEGANS (REPTILIA) - A SCANNING ELECTRON-MICROSCOPIC STUDY OF VASCULAR CORROSION CASTS

Gross supply, microvascular patterns, and drainage routes of the pinea l gland and its vascular relations with associated structures (dorsal sac, paraphysis, choroid plexus of the third ventricle) were studied b y scanning electron microscopy of microvascular corrosion casts in 10 specimens of the freshwater turtle, Pseudemys scripta elegans. Light m icroscopy of tissue sections (one transverse and one longitudinal seri es) served to attribute cast vascular territories to anatomical struct ures. The tubular pineal gland body is supplied bilaterally by small b ranches of the saccular artery, a branch of the lateral choroidal arte ry. Branches of the diencephalic artery supply the pineal stalk. The p ineal gland microvascular bed is a two-dimensional network that embrac es the tubular gland. The network is made up mainly of venules with fe w true capillaries. Venules draining the ventral surface of the pineal gland body join those coming from the choroid plexus of the third ven tricle and drain into the sagittal sinus. The less dense vascular netw ork embracing the dorsal surface of the pineal body drains directly in to the sagittal sinus. The pineal stalk drains into the diencephalic v ein or directly into the sagittal sinus. No efferent (venous) vascular connections capable as transport route for pineal secretions toward s urrounding telencephalic, diencephalic, or mesencephalic areas were fo und.