Bioscientifica Proceedings

Summary. Since one bull may be responsible for impregnating numerous cows, testicular function and fertility are of critical importance. Within this broad context, this review will focus on: the effects of nutrition on reproductive development; scrotal/testicular thermoregulation; breeding soundness; and sperm function/fertility. Bulls fed above-maintenance levels of energy and protein before 30 wk of age had increased luteinizing hormone pulse frequency, hast...

Summary. The mammalian sex chromosomes evolved from an ordinary pair of autosomes during evolution. Unlike the X chromosome that is highly conserved, the Y chromosome is poorly conserved among mammalian lineages. Several special features set the Y chromosome apart from the rest of genome: male-limited transmission, absence of recombination, abundance of Y-specific repetitive sequences, degeneration of Y-linked genes during evolution, acquisition of autosomal g...

Summary. In 2002, we reported that small fragments of testis tissue from immature mouse, pig or goat donors grafted in recipient mice undergo development, maturation and complete spermatogenesis, including the generation of fertilisation-competent murine, porcine or caprine sperm. Testis tissue xenografting (TTX) was then successfully applied using a range of donor species including laboratory/domestic/non-domestic animals and primates. This system offers a no...