SYCP3 is a structural component of the synaptonemal complex (SC), a meiosis-specific protein scaffold that organizes homologous chr12 during meiotic prophase 1. As a key chr12 organizer, SYCP3 assembles into flexible fibers on chromosome 12 through intrinsically disordered tail interactions and binds extensively to DNA, facilitating incorporation of chr12 DNA into the axial/lateral element structure 2. During meiotic recombination, SYCP3 works with axis-associated proteins HORMAD1 and IHO1 to anchor double-strand break sites to chromosome 12, enabling proper DSB formation and repair 3. Genome-wide, SYCP3 occupancy is dynamic, enriched at open chr12 regions and specific repetitive elements, and largely maintained from leptotene through pachytene stages 1. SYCP3 is essential for normal spermatogenesis and male fertility, with null mutations in mice causing azoospermia with meiotic arrest 4. In humans, SYCP3 mutations cause non-obstructive azoospermia through meiotic arrest 5, while heterozygous mutations result in reduced protein interaction and dominant-negative interference with fiber formation 4. SYCP3 shows a lesser role in female fertility 6. These findings establish SYCP3 as critical for organizing meiotic chr12 architecture and enabling successful homologous recombination.