The impact of an X-autosome translocation t(Xp(+);14q-), on ovulation, fert
ilization and embryo survival in carrier sows, was examined and compared wi
th these parameters of normal sows. Corpora lutea counts during week-2 and
week-4 of gestation were similar in normal and carrier sows (14.4 +/- 1.36
and 15.5 +/- 2.18) although embryo recovery(11.0 +/- 1.87 and 6.0 +/- 1.47)
was lower than that from normal sows (12.8 +/- 1.46 and 11.5 +/- 0.87), at
these stages. Among the embryos karyotyped from the week-2 embryos of carr
ier sows, 42% were normal, 26.4% were carriers and 31.6% were of unbalanced
chromosome make-up, and of the week-4 embryos of carriers, 33.3% were norm
al, 57.1% were carriers and 9.1% were chromosomally unbalanced females. The
preponderance of females among the unbalanced embryos recovered at week-2
of gestation (11_ and 1_) and the total absence of males among those recove
red at week-4, suggest that oocytes with unbalanced chromosome constitution
are eliminated before week-2 of gestation if they are fertilized by Y bear
ing sperm, and that the unbalanced oocytes fertilized by X bearing sperm su
rvive up to the peri-attachment stage even though all chromosomally unbalan
ced embryos are eliminated before term regardless of their sex.