Deep-Learning-Based Profiling of Mouse Sperm Head and Neck Morphology Reveals Coordinated Structural Variation.

BACKGROUND: Mammalian sperm head morphology varies across species and dictates fertilization capability. Rodent sperm have asymmetric, hook-shaped heads, complicating analysis. Despite widespread biomedical use, current tools poorly characterize these complex variations. OBJECTIVES: This study aimed to establish a robust framework for the precise, noninvasive, and quantitative analysis of mouse sperm morphology. MATERIALS AND METHODS: We developed ADAM-net (Anomaly-aware Deep-learning Architecture for Morphology), a machine-learning system for mouse sperm head and neck structures. Integrating a dataset preparation module, ResNet-18, and additional layers, it features two variants: ADAM-net-FL for fluorescence (FL) and ADAM-net-BF for bright-field (BF) images. RESULTS: ADAM-net-BF enables simultaneous analysis of the head and neck using noninvasively acquired BF images. Atypical head shapes were frequently associated with a neck in which the tail is attached perpendicular to the head axis, revealing a specific relationship between head shape and tail attachment pattern. Additionally, ADAM-net provided novel quantitative insights into testicular germ cell-specific HSF2-interacting lncRNA (Teshl)-knockout sperm defects, supporting its utility for mouse sperm morphology analysis. CONCLUSION: ADAM-net provides a standard and facile tool that will have applications in various reproductive studies, extending to the exploration of subtle structural dynamics such as the sperm head-tail alignment.