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Fig. 2. Double immunolabelling on squashed primary spermatocytes with anti-SCP3
(green) and anti-centromere CREST (red) sera. (A-A') Single focal plane
through an early pachytene spermatocyte. Sex chromosomes lie on the nuclear
periphery. Five autosomal centromeres and the sex chromosomes centromeres are
visible. X and Y short (Xp and Yp respectively) arms face each other.
(B-B') Single focal plane of an early pachytene spermatocyte in which
the sex chromosomes are in contact. Here the association is Xq-Yp and Xp-Yq
(arrows). (C-C') A mid pachytene spermatocyte in which both X and Y long
arms face each other (arrow). Bars, 5 µm in (A-C); 2 µm
(A'-C').