Ultrastructure of lymphatic endothelium
Recently, the lymphatics in the caprine hemal nodes have been described. The present study describes some ultrastructural features of the endothelium in the lymphatics of the goat hemal nodes.Hemal nodes located along the aorta, were collected from 15 clinically healthy, adult, West African dwarf goats. The tissues were fixed by either immersion or perfusion methods. For immersion fixation, the nodes were excised, and immersed temporarily in cold 2.5% glutaraldehyde in 0. IM cacodylate buffer, pH 7.3. After 5 min, the nodes were diced into 1-2 mm cubes and further fixed for 2 h in the same fixative. The par-aortic nodes were fixed by vascular perfusion. The two batches of tissues were post-fixed in 2% osmium tetroxide in cacodylate buffer, and further processing was done by conventional methods for transmission electron microscopy. The thin sections were examined and photographed in a Hitachi H-7000 electron microscope.The lymphatic wall comprised a continuous layer of fenestrated endothelial cells. The nuclei were oval and contained heterochromatin. The cytoplasm exhibited fenestrations that were closed by a membrane, and vesicular compartments bound on luminal and/or abluminal aspects by fenestrated membranes(Fig. 1). occasionally lymphocytes(Fig. 2) or erthyrocytes, most probably intransit, occupied these compartments. In material fixed by immersion, most of the vesicles contained flocculent material similar to that contained in the lumen(Fig. 3).