Novel Insights Into Egyptian Tortoise (Testudo kleinmanni) Tongue Morphology Using Immunofluorescence Analysis

Abstract The Egyptian tortoise (Testudo kleinmanni) exhibits remarkable adaptations; yet, significant gaps remain in the understanding of taste bud distribution and the molecular characteristics of its tongue cells. The unique adaptations were investigated using immunofluorescence with six specific antibodies, light microscopy, and scanning electron microscopy. Vimentin and nestin identified superficial taste buds in the lingual body, notably larger than those in the lingual root. The lingual root's fungiform papillae contained deep taste buds. Vimentin showed broad expression across all taste bud cells, while nestin specifically marked basal cells. Co-expression of platelet-derived growth factor receptor alpha (PDGFRα) and cluster of differentiation 34 indicated telocyte-like cells within the papillae. Circular and rectangular hyaline cartilage was also observed, and PDGFRα and SRY-box transcription factor 9 (SOX9) co-expression was demonstrated in chondrocytes, with SOX9 showing higher expression. Cluster of differentiation 19 also identified B-cell lymphocytes in the lingual root. This comprehensive study provides the first application of immunofluorescence to the Egyptian tortoise tongue. It represents new insights into the structure and molecular composition of taste buds of its tongue, highlights its role in physiological adaptation, and contributes to a better understanding of the biology species.