Fidelity of synapsis and transcriptional inactivation in a ring chromosome 4. (A): Immunostaining of synaptonemal complexes (SCP3, red), centromeres (blue), and recombination sites (MLH1, green) in spermatocyte from the patient with a ring chromosome 4 with microdeletion at 4p16.3. Spermatocyte shows asynapsed ring with two free ends (box). (B’-C’): Schematic representation of chromosome 4 indicating the asynapsed and synapsed parts of it. Linear chromosome 4 is shown in blue, ring chromosome 4 in green, synapsed area in yellow, and centromeres in red. (B- C): Immunolocalization of BRCA1 (green), centromeres (blue), and SCP3 (red) in spermatocytes of the patient. Sex chromosomes (excluding psedoautosomal region) and asynapsed area of chromosome 4 display BRCA1 labeling. (B and B’): Part of a spermatocyte with an incompletely synapsed ring associated with sex chromosomes. (C and C’): Part of a spermatocyte with an incompletely synapsed ring not associated with sex chromosomes.