Preimplantation human embryos and embryonic stem cells show comparable expression of stage-specific embryonic antigens

Cell-surface antigens provide invaluable tools for the identification of cells and for the analysis of cell differentiation. In particular, stage-specific embryonic antigens that are developmentally regulated during early embryogenesis are widely used as markers to monitor the differentiation of both mouse and human embryonic stem (ES) cells and their malignant counterparts, embryonic carcinoma (EC) cells. However, there are notable differences in the expression patterns of some such markers between human and mouse ES/EC cells, and hitherto it has been unclear whether this indicates significant differences between human and mouse embryos, or whether ES/EC cells correspond to distinct cell types within the early embryos of each species. We now show that human ES cells are characterized by the expression of the cell-surface antigens, SSEA3, SSEA4, TRA-1-60, and TRA-1-81, and by the lack of SSEA1, and that inner cell mass cells of the human blastocyst express a similar antigen profile, in contrast to the corresponding cells of the mouse embryo.

A comparison of three gonadotrophin-releasing hormone analogues in an in-vitro fertilization programme: a prospective randomized study

The use of gonadotrophin-releasing hormone analogues (GnRHa) has resulted in improved pregnancy rates in in-vitro fertilization (IVF) treatment cycles. Traditionally, short-acting analogues have been employed because of concerns over long-acting depot preparations causing profound suppression and luteal phase defects adversely affecting pregnancy and miscarriage rates. We randomized 60 IVF patients to receive a short-acting GnRHa, nafarelin or buserelin, or to receive a depot formulation, leuprorelin, all commenced in the early follicular phase and compared their effects on hormonal suppression and clinical outcome. We found that on day 15 of administration there was a significant difference in the suppression of oestradiol from initial concentrations, when patients on buserelin were compared with patients on nafarelin or leuprorelin (54 versus 72 and 65%; P < 0.05) and also in the number of patients satisfactorily suppressed, (80 versus 90 and 90%; P < 0.05), though there were no differences between the analogues by day 21. Similarly there was no difference in hormonal suppression during the stimulation phase or in implantation, pregnancy or miscarriage rates in comparing the three agonists. We conclude that with nafarelin and leuprorelin, stimulation with gonadotrophins may begin after 2 weeks of suppression and that long-acting GnRHa are as effective as short-acting analogues with no detrimental effects on the luteal phase.

Greater numbers of human spermatozoa associate with endosalpingeal cells derived from the isthmus compared with those from the ampulla

A simple co-culture bioassay system was used to investigate whether or not the anatomical origin affected the ability of epithelial cells from the human uterine (Fallopian) tube to 'bind' spermatozoa. This study was also used to identify some of the factors which may be involved in the regulation of sperm-epithelial interactions in vitro by comparing different tissue culture models and assessing the effect of oestradiol concentration. Epithelial explants harvested from different regions of human uterine tubes were co-incubated with a known concentration of motile donor spermatozoa. All results were adjusted to reflect a standard sperm concentration of 5 x 10(6)/ml. More spermatozoa associated per field of isthmic compared to ampullary epithelium [isthmus 9.5 +/- 0.9, ampulla 7.1 +/- 0.7 (mean +/- SEM); n = 36, P < 0.05, ANOVA] and cells from post-menopausal patients had an apparently reduced ability to bind spermatozoa [isthmus 5.5 +/- 2.0, ampulla 4.3 +/- 1.4 (mean +/- SEM); n = 4]. Neither menstrual cycle stage nor addition of mid-cycle concentrations of 17beta-oestradiol (750 pmol/l) affected the number of spermatozoa which bound to epithelium from either tubal region. In addition, the number of spermatozoa which bound per field of polarized explants was greater (P < 0.05) than that bound to dissociated primary and passaged epithelial cell monolayers. This report is the first to provide evidence suggestive of a role for sperm-epithelial binding in the formation of an isthmic sperm reservoir in the human uterine tube. Results also indicate that oestrogen is not involved in the regulation of these interactions, and that cell polarity is an important factor for such associations in vitro.

Effects of growth hormone on intestinal morphology of genetically dwarf rats

Three groups of Lewis rat were studied: dwarf rats, genetically deficient in growth hormone; rehabilitated dwarf rats treated with exogenous growth hormone (GH); and normal wild-type rats. The small intestine of each animal was removed and simple random transverse sections were taken from the proximal and distal regions. The profile areas of villi, crypt and muscle were estimated by point count analysis and combined with intestinal length measurements to obtain absolute volumes. Villus and primary mucosal surface areas were estimated from intersection counts and linear measurements were made of epithelial cell height. Distally, villous volume and surface area were reduced by 42% and 39%, respectively, in the dwarfs compared with controls. These features were significantly smaller (P < 0.01) in dwarfs distally than proximally. Crypt volume and epithelial cell height were decreased equally in both proximal and distal regions of the intestine of dwarf rats. Following GH administration both features increased, crypt volume overshooting control values. These results indicate that GH deficiency has a subtle effect on intestinal morphology and that the intestine is more sensitive distally than proximally. Reconstitution with GH is capable of reversing many of these changes.