Electron microscopic and cytochemical studies of the thrombocytes of the tortoise (Geoclemys reevesii).

The thrombocytes of the tortoise (Geoclemys reevesii) were studied at the electron microscopic level. The presence of a surface connected canalicular system, composed of numerous anastomosing canaliculi, has been demonstrated by the ruthenium red technique. However, monoamine storage organelles have not been found in tortoise thrombocytes. Peroxidase activity is localised to the nuclear envelope and the rough surfaced endoplasmic reticulum, but is not present in the Golgi apparatus or granules. Acid phosphatase is localised to the large inclusions with myelin bodies, but is not found in the electron-lucent small granules. These results are discussed in relation to those from comparable studies of mammalian and submammalian thrombocytes.