Three-dimensional reconstruction of rat sperm using volume electron microscopy

• Utilized ATUM-SEM volume electron microscopy to achieve comprehensive 3D ultrastructural reconstruction of rat sperm during spermiogenesis. • Nucleus volume dramatically reduces to 10% of original size, while acrosomal vesicles from Golgi converge and elongate to form a cap-like structure defining the sperm head. • Mitochondria migrate from beneath the cell membrane to the sperm tail, forming a helical mitochondrial sheath essential for sperm motility. • Reconstructed the chromatoid body, a cloud-like mRNA-storing structure, providing new insights into the molecular organization of spermatids.