MUSCULAR-APONEUROTIC SYSTEM OF THE SKIN OF THE FACE, AS A UNIQUE STRUCTURE OF THE FACIAL SCULL (CRANIUM FACIALIS) OF HIGHER ANIMALS

Aim: The purpose of this research was to study the organization of collagen in animal skin in order to find similar SMAS structures. Materials and Methods: The studies were conducted on skin samples from sheep and pigs (from the facial area), as well as trout. The obtained samples were studied under ultraviolet radiation. The Qscan Plus (AIOBIO, South Korea) device with a wavelength of 405 nm was used as a source of ultraviolet radiation. Skin sections were made at right and oblique angles in order to establish the spatial configuration of collagen fibers. The density (concentration) of fibers per unit area was calculated qualitatively by micro- and macroscopic methods with photometry. The results were evaluated in the Microsoft Office software package. Results: In all the studied facial skin samples, the presence of collagen luminescent white in ultraviolet light was detected. The collagen was located laminarly, parallel to the skin surface, without the formation of a three- dimensional mesh structure characteristic of the SMAS of human facial skin. Conclusions: The data confirm the presence of collagen in the facial skin of the studied animals. However, unlike human facial skin, the characteristic three-dimensional collagen organization of the SMAS has not been detected. Further research is needed to determine the evolutionary origin of the SMAS and identify the factors that determine its formation. Conclusion: No structures similar to SMAS were found in the animals used in the experiment. This is most likely due to the function performed by SMAS – the transmission of facial contractions to the skin. Probably, the structural organization of collagen on the human face is unique. Further research is required to accurately determine the evolutionary development of SMAS.