The anlage and development of the nasal section in the embryonic period of the human ontogenesis

Abstract

While investigating we carried out the sequential microscopic sections of 32 human embryos by fixing them in the 10-12% solution of the neutral formalin. The preparations had been dehydrated by keeping them in the bank of alcohol and the consequent filling up with the paraffin. With the help of the sliding microtome we carried out the sequential microscopic sections colored by hematoxylin and eosin or boron carmine during 1-3 days and investigated with the help of the ordinary microscope or binocular lens MBS-10. For investigation of the forms, positions and relief of the nasal septum structures we used classical means of the graphical and plastic reengineering. Morphometry was carried out with the help of the microruler. It was determined that at the beginning of the embryonic period nasal placodes develop, and in the middle of the embryonic period nasal fossae develop on their free surface. Nasal fossae are bounded by the horseshoe-shaped protuberances, which are shaped in the form of the rollers - the primary stage of the middle and side nasal processes formation. Later on, there is an intensive growth of the nasal fossae and adjacent structures, as a result of which they develop into the nasal chambers. At the end of the embryonic period there happens a break of the nasal chambers into the primary mouth cavity with the development of the primary choanae. The internasal septum develops with the help of the middle nasal processes coalescence. The primary nasal cavity from the primary mouth cavity is separated by the primary palate.