From Big Medical Encyclopedia

METORIZIS (between, later, through + horizo to delimit Greek meta) — the phenomenon of the shift (redemarkation) of borders between germinal leaves or embryonal rudiments and respectively between their fabric derivatives as in phylogenesis (at descendants in comparison with ancestors), and in ontogenesis, i.e. in process of this individual organism.

The term «metorizis» is offered by B. M. Shimkevich (1908); M.'s theory developed by it, and also A. N. Severtsov, A. A. Zavarzin and N. G. Hlopin — important addition and an organic component of the theory germinal leaves (see), essential section of evolutionary histology. Evolutionary shift of borders between ectoderm (see) and entoderm (see) from edges of an actinostome in depth of an intestinal tube in the perednezadny direction led to the fact that at the majority of animals the front gut (an oral cavity, a throat, a gullet) and its derivatives (visceral furrows, respiratory tracts, etc.) were covered by an epithelium not of intestinal, but skin type (ectodermal). The person has a border between Epi - and enterodermalny epiteliya (skin and intestinal types) lies at the level of transition of a gullet to a stomach, but at many animals — still kaudalny. Other example — substitution of a single-layer epithelium of a mesodermal origin multilayer in a vagina. Depending on a phase of an ovarian and menstrual cycle (at the person and monkeys) or a cycle of a spout (at other mammals) the border between both types epiteliyev is periodically displaced in cranial, in the caudal direction: the epidermal epithelium grows forward into a neck and even a body of the womb, recedes back (metoristichesky modulations). Islands of an ectodermal epithelium can remain on sites of a uterine epithelium. At the same time in cases of a malignancy there is cancer of epidermal type. M.'s theory allows to explain such cases of a carcinogenesis with disturbance of boundary relationship between diverse fabrics («metoristichesky excesses»). Preservation of a single-layer (myullerovsky) epithelium in a vagina also belongs to metoristichesky excesses that contributes to emergence of pathological processes.

Bibliography: Knorre A. G. Embryonal histogenesis, page 77, L., 1971; To N about e A solution. And Mikhaylov V. P. The principle of a metorizis of V. M. Shimkevich and his value for histology, Arkh. annate., gistol, and embriol., t. 40, No. 1, page 3, 1961, bibliogr.; Shimkevich V. M. Metorizis as embryological principle, Izv. And-megapixel, AN, is gray. 6, t. 3, No. 18, page 997, 1908.

V. P. Mikhaylov.