File:Blood-thymus barrier EM01.jpg

Blood-Thymus Barrier - Electron micrograph

Capillary of the Thymus cortex. X 27,000.

In this specimen care has been taken to retain the blood in the vascular bed during fixation. The capillary, lumen is wide open and contains both plasma and red blood cells; in the cytoplasm of the attenuated endo- thelial cells (End), plasmalemmal vesicles are few in numbers.

The vessel is enclosed in a coaxial canal formed by the surrounding thymic parenchymal cells; a macrophage containing residual bodies (asterisks) encompasses most of the circumference of the vessel and sends processes into the vascular adventitia (Adv).

Below and on the left, the parenchymal front bounding the vascular adventia is represented by a process of a reticular cell.

Reference

Raviola E & Karnovsky MJ. (1972). Evidence for a blood-thymus barrier using electron-opaque tracers. J. Exp. Med. , 136, 466-98. PMID: 4115129

Fig. 2. modified in size, contract and labelling.

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