Chromosome synapsis in pachytene spermatocytes and diakinesis/metaphase I cell of F1 hybrid E. tancrei (2n = 50, NF = 56). a The scheme reflects a prognosis for chromosome synapsis in prophase I of meiosis [Trivalent №1 Rb(2/2.18/18), trivalent №2 Rb(4/4.12/12), and tetravalent Rb(5/5.9/9.13/13)]. M – metacentric, A – acrocentric b Electron micrograph of part of the spread spermatocyte. Nb – DAPI-positive nucleolus-like bodyc Spermatocyte is stained with DAPI (blue). Immunostaining with antibodies to SCP 3 (green) and to MLH1 (yellow) d Autosome’s axial element (A) stiking to Nb of sex bivalent (autosome – sex chromosome association) e Open SC trivalent f Diakinesis/Metaphase I cell showing 18 pairing elements, XX bivalent, two univalents (Un), two trivalents (Tr) and tetravalent. Scale bar: 5 μm.