Daf. Villagomez et al., SYNAPTONEMAL COMPLEX-ANALYSIS IN A BOAR WITH TERTIARY TRISOMY, PRODUCT OF A RCP(7-17)(Q26-Q11) TRANSLOCATION, Hereditas, 122(3), 1995, pp. 269-277
Synaptonemal complex analysis by electron microscopy showed a trivalen
t formed by pairing of chromosome 17(7) with chromosome pair 7 in two
zygotene cells. In 89 pachytene cells (75.4%) the chromosome 17(7) occ
urred as a univalent with the axis being unpaired, in the shape of a r
ing (60.6%), a rod (38.2%) or self-paired (1 cell). Thirty-four (38.2%
) of the univalents were paired or associated with the sex bivalent. T
wenty-five (21.2%) of the 118 pachytene cells analysed demonstrated di
fferent types of trivalent pairing: the 17(7) chromosome paired with c
hromosome pair 7 in 24 cells and with pair 17 in one cell. Moreover, i
n 4 cells, chromosome 17(7) was paired with both pair 7 and pair 17, f
orming a pentavalent. Trivalent association with XY was observed in 4
cells. Nineteen bivalents plus a univalent (8 cells), and eighteen biv
alents plus a trivalent (11 cells), were found during conventional mei
otic investigation of diakinesis-metaphase I. Though the boar demonstr
ated a normal testicular histology, a qualitatively deviant semen pict
ure was evident.