[The fine structure of the lymphatic vessels of the urinary bladder of small Chelonia (Testudo graeca and Emys europea)].

The fine structure of lymphatic vessels in the subepithelial, intramuscular and subserosal layers of the bladder of small Chelonia (Testudo graeca and Emys europaea) have been investigated during the winter and summer seasons. The vessels are made up of flat endothelial cells, which abluminal surface is encircled by a thick layer of connective fibrils. Peripheral cytoplasmatic processes of adjacent endothelial cells are connected by specialized junctional complexes (zonulae adhaerentes and occludentes) and show an uninterrupted course. No seasonal cytological modification is noted, whereas some morphological aspects typical of each individual network can be detected. Comparative aspects and the presence of intra endothelial channels are stressed. The latter, together with micropinocytotic vesicles, seem to play an essential role in the exchanges with the interstitium, while the intercellular junctions do not undergo any modification.