PACULARITIES OF EMBRYOGENESIS OF NASAL REGION CONSTITUTIONAL STRUCTURES IN SOME MAMMALS

Abstract

The aim of the study was to determine general regularities and specific features of prenatal morphogenesis of nasal region and structures in a human being and some mammals. We studied 75 specimens of human fetuses and embryos and 85 mammals’ specimens in different periods of prenatal development by using complex of morphological methods (anthropometry, morphometrics, microscopy, three-dimensional computer constructing, and statistical analysis). It has been determined that morphogenesis of the nasal region in mammals has the following general features: a) development of the nasal cavity begins with nasal placodes that have ectodermal origin; b) formation of the nasal cavity passes five sequential stages: the olfactory placode, nasal fossa, nasal sacks, primary nasal cavity and definitive nasal cavity; c) the formation of nasal cavity obligatory includes physiological atresia of nostrils, nasal-palatine channels and ducts of vomeronasal organ which precedes the process of palatine processes becoming horizontal. Vomeronasal organ in studied species is established as a region of epithelium in the anterio-inferior part of the nasal septum, has medial orientation and is connected with nasal cavity. Majority of studied species show that glands of maxillary sinus begin their development on the 12-13th stage of embryogenesis, respiratory glands – on 15-16th. Vomeronasal and olfactory glands glands begin to form later on 14-15th stages.Formation of nasal glands in white rats occurs at earlier stages. Regularities of nasal glands morphogenesis have certain development sequences: first develops lateral nasal gland, then maxillary sinus glands, then respiratory and olfactory. Nasal cavity of embryos at 16th stage of development includes the following glands: pair lateral nasal gland (except humans), single respiratory, olfactory and maxillary glands. In some animals two pairs of anterior medial glands (in rodents) and a pair of vomeronasal nasal glands (in rodents and carnivores) were identified.