[Structure of lymphatic vessels in the rat thyroid gland].

The lymphatic bed of the thyroid gland has been studied in 24 intact rats. Three techniques facilitating to reveal lymphatic vessels in the organ have been used: preparation of semithin sections, injection of the blood bed with methyl methacrylate with a successive chemical extraction of the preparations, injection of the blood bed with liquid solution of methyl methacrylate with a consecutive study of the preparations in the scanning electron microscope. Methods of electron histochemistry (revealing horseradish peroxidase) and kryofractography have been applied.

[Vascular endothelium (review). I. General morphology. 2A: histogenesis of the vascular endothelium].

Determination, differentiation, and specialization of vascular endothelium are the main steps of its histogenesis. The source of the first determined endothelioblasts are condensed mesenchymal cells (blood islands) at the yolk sac (extraembryonal) and also in the intraembryonal mesenchyme. The term of determination is not yet known.