A Histological and Anatomical Analyses of Rhinarium in the Yak (Bos grunniens)

Abstract

This study was conducted to reveal the gross and histological structures and area size of the rhinarium on 20 yak heads. Macroscopic examinations were used to reveal macroscopic structures; Mallory's triple staining and SEM examination were used for histological structures, and the Fıjı program was used to determine the rhinarium area size. In macroscopic examinations, it was determined that the yak rhinarium consists of dark, moist and hairless skin located between the nostrils and the upper lip and that it features a philtrum in the upper lip region. In SEM examinations, the skin in this region was composed of epidermis and dermis layers and that the skin surface had areas of different sizes separated by primary grooves containing single, double or triple epidermal domes. In triple staining, it was determined that the skin was composed of epidermis, dermis and hypodermis. The dermis and epidermis layers were tightly connected to each other, and the stratum corneum was thick in the epidermis layer, while connective tissue threads and serous glands and ducts were dense in the dermis layer. According to the findings obtained from the study, it was concluded that the tip of the yak's nose has differentiated to adapt to high altitude, cold and harsh weather conditions; the philtrum seen in the upper lip section of the rhinarium can be used to distinguish yak from other cattle breeds, and the dome areas of different shapes and numbers seen on the epidermal surface can be used in the individual identification of animals.