No abstract

It is well established that chromosomes occupy distinct positions within the interphase nuclei, conferring a potential functional implication to the genome. In addition, alterations in the nuclear organisation patterns have been associated with disease phenotypes (e.g. cancer or laminopathies). The human sperm is the smallest cell in the body with specific DNA packaging and the mission of delivering the paternal genome to the oocyte during fertilisation. Studies of nuclear organisation in the sperm have postulated nonrandom chromosome position and have proposed a chromocentre model with the centromeres facing toward the interior and the telomeres toward the periphery of the nucleus. Most studies have assessed the nuclear address in the sperm longitudinally predominantly using centromeric or telomeric probes and to a lesser extent with whole chromosome paints. To date, studies investigating the radial organisation of human sperm have been limited. The purpose of this study was to utilise whole chromosome paints for six clinically important chromosomes (18, 19, 21, 22, X, and Y) to investigate nuclear address by assessing their radial and longitudinal nuclear organisation. A total of 10,800 sperm were analysed in nine normozoospermic individuals. The results have shown nonrandom chromosome position for all chromosomes using both methods of analysis. We present novel radial and polar analysis of chromosome territory localization within the human sperm nucleus. Specifically, a hierarchical organisation was observed radially with chromosomes organised from the interior to the periphery (chromosomes 22, 21, Y, X, 19, and 18 respectively) and polar organisation from the sperm head to tail (chromosomes X, 19, Y, 22, 21, and 18, respectively). We provide evidence of defined nuclear organisation in the human sperm and discuss the function of organisation and potential possible clinical ramifications of these results in regards to male infertility and early human development.

No abstract

No abstract

A study was undertaken to evaluate embryonic development and establish pregnancies with human embryos after in-vitro culture in two different systems. Treatment A consisted of culturing zygotes in serum-supplemented human tubal fluid culture medium (HTF). Treatment B consisted of culturing zygotes on a monolayer of bovine oviductal epithelial cells with HTF. At the time of embryo replacement, embryos in treatment B had 4.11 blastomeres present, which was greater (P < 0.05) than the 3.81 present for embryos in treatment A. In addition, the cellular fragmentation rate for treatment A embryos was 1.10, which was greater (P < 0.05) than the fragmentation rate of 0.38 for embryos within treatment B. The incidence of ongoing pregnancy was higher after replacement of co-cultured embryos (treatment B) (43%) than replacement of conventionally cultured embryos (treatment A) (29%). The implantation rate per embryo increased (P < 0.05) from 11.5 to 18.4% after co-culture. In treatment B the proportion of 'spare' embryos developing to expanded blastocysts was 58.5%, which was greater (P < 0.05) than the blastocyst development rate of 29.3% observed for embryos within treatment A.