MEIOTIC CHROMOSOME ASYNAPSIS IN A BOAR WITH A RECIPROCAL TRANSLOCATION AND ACQUIRED TESTICULAR DEGENERATION

During a period of performance testing, a boar used for artificial ins emination purposes was found responsible for reduced litter size and s lightly increased incidence of repeat breeding. The qualitative and qu antitative semen characteristics, however, were within normal limits. Later, evaluation of the semen during a period of 3 months revealed a decreased sperm concentration, but sperm cell morphology and mobility were normal. At castration, the boar, which had suffered from scrotal inflammation, was found to have hypoplastic gonads, the right testis b eing smaller than the left one. Histologically there was spermatogenic arrest at the primary spermatocyte level in almost all tubules of the right testis. In the left testis, histology was more heterogeneous, w ith some tubules containing all developmental stages, while others had an almost complete spermatogenic arrest. Cytogenetically the boar was carrying a translocation, rcp(2;14)(p14;q23). Synaptonemal complex an alysis revealed complete quadrivalent pairing in 21 out of 43 cells an alysed. The remaining cells demonstrated quadrivalents with axes moder ately or extensively unpaired. There was a distinct difference between cells from the right vs. the left testis. The latter cells showed mor e completely paired translocation configurations- Moreover, in 14 and 7 cells analysed from the right and left testis, respectively, the tra nslocation configuration could not be identified. This was due to chro mosome asynapsis and frequent occurrence of gaps in the chromosomes, i ncluding others than those of the translocation, plus an abundant cell ular deposit which formed a dense cell background. Association or pair ing of the quadrivalent with the sex bivalent was seen in one cell onl y. At diakinesis MI, most cells had a ring-shaped quadrivalent- It is believed that the asynapsis of chromosomes during the prophase of meio sis was to a large extent due to the degeneration caused by the inflam mation processes.