Integrative Phenotypic and Transcriptomic Dynamics of Hair Follicle Development and Fur Quality in Rex Rabbits.

Abstract

Rex rabbit fur quality determines economic value, yet the age-dependent dynamics of hair follicle development and their molecular drivers are largely unknown. Here, we performed a time-series integrative analysis combining phenotypic measurements, quantitative histomorphology, and transcriptome sequencing in Yongqing Rex rabbits across 1 to 6 months of age (10 rabbits per month). Fur thickness exhibited a pattern of increase, stabilization, and subsequent increase, with no significant differences between 2M and 4M (p > 0.05). Coat density peaked at 6M, with an average pelt area of 1358.20 ± 52.43 cm² at 5M and 6M. Fiber length increased and then plateaued, whereas hair diameter showed an increase-decrease-stabilization pattern. Histological analysis revealed a significant age-related decrease in the number of follicle clusters, particularly from 1M to 3M (p < 0.05). Primary hair follicle density was the highest at 1M (p < 0.01) and fluctuated subsequently, whereas secondary hair follicle density increased continuously (p < 0.01). Melanin granules increased significantly from 1M to 4M and peaked at the 4M (p < 0.05). Further, transcriptomic identified 1168, 4204, and 3431 differentially expressed genes (DEGs) for 3M versus 1M, 5M versus 1M, and 5M versus 3M, respectively, with 187 common DEGs including FOXN1, FGF10, and DCN. GO and KEGG analysis indicated significant enrichment in processes such as keratinization, keratinocyte differentiation, ECM-receptor interaction, and the PI3K-Akt signaling pathway. Collectively, our findings reveal the dynamic patterns of hair follicle development in Rex rabbits across phenotypic, histological, and molecular levels, providing a theoretical basis for the genetic regulation of fur quality.