Gerota Method

GEROTA METHOD (Gerota) - injection of lymphatic vessels, a method of injecting them with fluid, proposed by Professor Gerota of the University of Bucharest. The thoracic duct (and large lymphatic vessels) can be dissected when naturally filled; but since lymphatic vessels of internal organs become more prominent with lymph stasis, the thoracic duct began to be ligated (Willis) and finally the vessels were injected by inserting a cannula through which water (sometimes colored), milk (with air blown in), provence oil, colored fat (Ruysch and Swammerdam), etc., were introduced. Injection with mercury was first used by Nuck (according to Burgavy, who could transform it into an amalgam of lead and tin). Mascagni used a glass cylinder with a capillary tube drawn at a right angle for such injections. Syringes were first used by R. de Graaf and C. Bartholin. At the end of the 18th century, the indirect, interstitial, parenchymal injection method was also used, where the lymphatic vessels were naturally damaged and the injected fluid entered them. From the second half of the 19th century, special injection apparatuses were constructed by various researchers, consisting of a receiver for the injected fluid, a tube, and an additional part for the cannula (metal or glass). Particularly brilliant results were achieved by Teichmann (1861) and Sappey (1874), who used exclusively mercury. Both the instruments for these injections and the composition of the injected masses and fluids are extremely diverse, as are the methods of studying the lymphatic system; in addition to those mentioned, impregnation with silver nitrate and physiological injection - introduction of the injected fluid into lymphatic vessels by natural pathways should be noted. Mercury injections, which produce extremely beautiful specimens but are unsuitable for microscopic examination, have other major drawbacks: vessels strongly stretched by the heavy fluid easily rupture due to the significant pressure used during injection; preserving fluids usually chemically affect the mercury; mercury also escapes from dry specimens due to the fragility of the vessels; much time is spent on preparing the specimen, it is expensive, etc. Gerota used glass syringes of 10 cubic cm and glass cannulas, initially made to special order by Gerota. Due to the difficulty of cleaning syringes and their tendency to leak fluid, Bartels proposed a modified 'Record' syringe of 2 cubic cm, which is detachable and consists of a graduated glass tube with a metal (nickel silver) 'nose' with a button for pin connection with the additional part, into which a glass cannula drawn into a capillary tube over an alcohol lamp flame is inserted (at Gerota's suggestion, it is wrapped in thin glove leather that does not let the fluid pass through); the rear part of the tube is equipped with a ring, also with a pin connection, with an additional part equipped with two rings for the middle and index fingers; the piston is metal, with a head having a ring-shaped notch; the air contained in it ensures a tight seal; the piston rod is equipped with a ring for the thumb. A set of glass cannulas of various lengths, straight and curved, should be available, from which the fluid should not drip but only flow in a thin stream when the piston is pressed. After testing and strict criticism of various mixtures, Gerota and Bartels consider Prussian blue in tubes the best, which is thoroughly ground in a porcelain mortar with turpentine, and then a few drops of ether are added. Good is also transparent green cinnabar with turpentine and ether or with a drier, turpentine or chloroform. These mixtures are filtered through cloth or thin chamois or leather moistened with turpentine. Iosifov used liquid Chinese ink diluted with water, and Stefanis - various oil paints. For injection, as fresh material as possible, moistened in water, should be used. Cleaning the field of operation with a tampon also serves as a light massage that helps the injected fluid to advance in the vessels. Malinovsky recommends greasing hands with vaseline or liquid paraffin to avoid difficult-to-remove contamination. For preserving injected objects, formalin diluted 10 times or more is recommended; specimens that have become too dense are washed with water; for examination under a magnifying glass, they are cleared in xylene. Long-term preservation - in weaker formalin solutions, in alcohol vapors, and in dry form (after preliminary treatment with glycerin). Glue and gelatin injections require heating, and in some cases - performing the operation under water; such mass also does not penetrate very well. According to Gerota's method, relatively limited but complete areas are injected. Teichmann's mass is also suitable for large vessels. Successful use of the method requires great patience and considerable experience, but for scientific work it is currently the best.