RESUMO
After examining about 600 urinary calculus, their structure was characterised. Four kinds of renal stone structures were distinguished. A few particular structures were presented such as the ones whose centres were empty i.e. they had a cavity inside either completely empty or filled with loose or granulated powder (they amounted to 8 pieces i.e. 1.2% of all examined urinary stones). Another specific case was phosphate renal stone with a very complex layer structure. It was concluded that the establishing of so called nucleus is not decisive in the process of building up renal stones. There exist the renal stones which are built up of separate, big crystals, which cannot contain any nucleus or of solid mass of crystalline powder. The reasons of building up renal stones are only of physics-chemical nature i.e. they result from a simple phenomenon in which crystallization of chemical compounds from supersaturated solutions is involved.
