[The basic types and forms of the fine structure of mitochondrial cristae: the degree of their evolutionary stability (capacity for morphological transformations)].

The organellological analysis being made of the fine structure of mitochondria in different species of the kingdom Protista, and in different cells of representatives of the kingdoms Plantae and Animalia (Metazoa). On the base of this analysis the following classification of types and forms of the fine structure of mitochondrial cristae is proposed. The Ist type, with lamellar (flat) cristae includes four morphological forms: ribbon, sheet, bundle-like and rounded ones (discoidal and plate-like). The 2nd type, with vesicular cristae, includes bubble, ampule, and sac-like ones. The 3rd type with tubular cristae. Among the representatives of each kingdom (Protista, Plantae and Metazoa) all the three types of mitochondrial cristae have been observed. The majority of cells of higher plants and higher animals have lamellar mitochondrial cristae, but sometimes (in some tissues) there are cells with tubular or vesicular mitochondrial cristae. On the base of the above classification some other conclusions have been made. Among the eukaryotes the vesicular cristae are spread as widely as tubular and lamellar ones. Only in a few macrotaxa (superphyla and phyla) of Protista all the investigated organisms have mitochondria of similar cristal organization. For example, Ciliophora have only tubular, and Cryptophyta only lamellar mitochondrial cristae. In the majority of protistan macrotaxa a certain mitochondrial type of cristae may dominate, but there is the number of species with some different mitochondrial patterns (Euglenophyta, Chlorophyta, Chrysophyta, Mycetozoa, etc.). In some macrotaxa (Chrysophyta, Mycetozoa, etc.) such mitochondrial patterns as mentioned above, are characteristic of the lower organisms. Finally, in some macrotaxa of Protista mitochondrial cristae of two or three types may appear in different species, sometimes even within the same genus; for example--Sporozoa, Myxospora and Ascetospora. In the course of ontogenesis of the vertebrates and insects, cell mitochondria in some of their tissues can change their morphological type from lamellar to tubular or vesicular. Similar transformations of mitochondrial cristae were observed in the life cycles of some trypanosomes (Kinetoplastida) and in the flagellate Polytoma (Chlorophyta) due to modifications in the culture conditions. It is undoubtedly that the principle of morphological concervatism in the organization of mitochondrial cristae may be used for purposes of systematics and phylogeny, however only after a thorough comparative organellological analysis of the fine structure in numerous species of the examined taxon.