In vertebrates, synaptic bodies (SBs) are conspicuous synaptic organelles of afferent synapses of retina, inner ear, lateral line organ and pineal gland. In electron microscopic sections they are electron-dense organelles surrounded by electron-lucent vesicles. Ribbon- or rod-like profiles (width: 30 - 40 nm; length: 150 - 200 nm) can be distinguished from round ones (diameter >70 nm) and rare irregular profiles (Vollrath '81; Mc Nulty '92). It was the aim of this investigation to reconstruct the structure of pineal SBs in different vertebrates in three dimensions to draw conclusions of their general appearance.
Pineal tissue of guinea-pig, rat and chicken was examined. Transmission electron microscope photos from up to 27 serial sections with a known distance (50nm) of groups of SBs were scanned and processed (controlled superimposition of corresponding organelles from adjacent sections, involving rotation and shifting of the scanned image) by a self - written programme in Interactive Data Language (IDL®).
The resulting 3D-array was further processed by NeurOPS (neurosurgical operation-planning and simulation software developed at the IMSD) allowing 3D visualisation of SBs. The three-dimensional images were printed from different angles to elucidate the appearance of SBs in space. It was found that in general most SBs were plates, sometimes curved, with irregular edges. The quantity of other SBs (spheres, ovoid or irregular structures) varied depending on the species and experimental conditions.
The presently used method to evaluate scanned photographs can be used for producing 3D- reconstructions from serial images in general.

References:
McNulty JA, Fox L. Pinealocyte synaptic ribbons and neuroendocrine function. Microsc Res Tech 21, 1992
Vollrath L. The pineal organ. In: Oksche A and Vollrath L (eds) Handbuch der mikroskopischen Anatomie des Menschen, Springer, 1981

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