[Microscopic study of the nasal cartilaginous framework in Chinese population]

Objective: To systematically investigate the detailed anatomical characteristics of the nasal cartilaginous framework in Chinese adults via anatomical observation, histological analysis and micro-magnetic resonance imaging (μMRI), and to clarify its clinical significance for functional rhinoplasty. Methods: A total of 16 adult Chinese cadaveric nasal specimens (9 formalin-fixed specimens and 7 fresh frozen specimens), including 5 female specimens, were subjected to anatomical observation. The dorsal septal cartilages (DSC) were completely dissected to observe their structural configuration and morphology, as well as the clefts between the dorsal margin of the upper lateral cartilages (ULCs) and the quadrangular cartilage (QC), which were analyzed by heminasal unit. Another 7 formalin-fixed male nasal specimens underwent μMRI scanning followed by hematoxylin-eosin staining, Masson's trichrome staining and elastic fiber staining. Morphological features of coronal μMRI sections and the structural and cellular characteristics of histological slices were observed. Statistical analysis was performed using SPSS 24 software. Results: Anatomical observations revealed that the DSC represented an integrated anatomical structure composed of the QC and alar ULCs extending bilaterally from its dorsal margin. Although clefts between the caudal ends of ULCs and QC were observed in 62.5% (20/32) of heminasal specimens, their cephalic segments presented as continuous cartilage tissue, which confirmed that the DSC functioned as a single integrated unit. Based on the included angle between ULCs and QC, the ULCs in this study were classified into the adducted wing type (included angle<45°, 6/16) and the abducted wing type (included angle>45°, 10/16). Histological findings identified two proliferative patterns of adult nasal cartilage: chondrocyte mitosis and chondrogenic differentiation of perichondrial cells. Chondrocytes in the dorsal region of the QC were smaller and less metabolically active, indicating this region may serve as a proliferative center; by contrast, ventral chondrocytes exhibited stronger metabolic activity and extracellular secretory capacity. Statistically significant differences were found in cell size and isogenous group density between the two regions (all P<0.05). Four connection patterns were identified between ULCs and lower lateral cartilages (LLCs): end-to-end contact (1/7), curled overlapping (2/7), interlaced overlapping with fibrous adhesion (1/7), and sesamoid cartilage-mediated connection (3/7). The medial crura of LLCs overlapped or formed end-to-end junctions with the caudal margin of the QC, which shaped the nasal tip morphology of Chinese individuals. Conclusion: This study systematically elaborates the unique anatomical features of the nasal cartilaginous framework in Chinese adults, particularly the dynamic wing-shaped integrated DSC structure, which acts as the anatomical basis for nasal contour and nasal valve function.