Ion microscopy based on laser-cooled cesium atoms.

We demonstrate a prototype of a Focused Ion Beam machine based on the ionization of a laser-cooled cesium beam and adapted for imaging and modifying different surfaces in the few-tens nanometer range. Efficient atomic ionization is obtained by laser promoting ground-state atoms into a target excited Rydberg state, then field-ionizing them in an electric field gradient. The method allows obtaining ion currents up to 130pA. Comparison with the standard direct photo-ionization of the atomic beam shows, in our conditions, a 40-times larger ion yield. Preliminary imaging results at ion energies in the 1-5keV range are obtained with a resolution around 40nm, in the present version of the prototype. Our ion beam is expected to be extremely monochromatic, with an energy spread of the order of the eV, offering great prospects for lithography, imaging and surface analysis.

Oocyte morphology and early zygote cleavage does not appear to be related to intrafollicular concentrations of inhibin-A or -B.

PURPOSE: The aim was to investigate the relationship of intrafollicular inhibin dimers A and B with human oocyte morphology and subsequent embryo potential. METHODS: Sixty-eight oocytes were isolated from 31 women undertaking intracytoplasmic sperm injection (ICSI). Estradiol, progesterone, testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, sex hormone-binding globulin, inhibin-A and inhibin-B was assayed in corresponding follicular fluid. RESULTS: The mean (+/- SD) concentration for inhibin-A was 9.7 +/- 9.8 ng/ml (range, 1.1-60.0 ng/ml) and for inhibin-B was 269.4 +/- 185.2 ng/ml (range, 33.1-811.0 ng/ml). In a correlation matrix there were no marked relationships (r < 0.556) between inhibin and steroid or gonadotropin concentrations. Similarly, when inhibin concentrations were divided according to whether the oocytes had mature or immature cumulous complexes, were viable or necrotic, were meiotically immature or mature, became fertilized or not, or had different embryo gradings after cleavage, no statistically significant difference could be seen between groupings. CONCLUSIONS: Because the range of values was large and the data often skewed, neither inhibin dimer has discriminatory power to reflect the potential of the oocyte.

Failure to collect oocytes in assisted reproductive technology: a retrospective.

While there is much information and discussion on pregnancy failure after assisted reproductive technologies, less emphasis is placed on the failure to collect oocytes after apparently successful ovarian stimulation. This retrospective survey reviewed 4973 treatment cycles in order to obtain information about the likelihood of this event. Overall 42 women (43 treatment cycles) failed to have oocytes collected [0.86% of treatments started and 0.92% of women given human chorionic gonadotrophin (HCG)]. However, in only six cases was this failure unexpected (0.1%) with no obvious potential clinical reason (i.e. all six cases had: HCG administered; more than two follicles >15 mm in diameter; oestradiol values >2000 pmol/l; <38 years old; normal body mass index). Indifference concerning uncommon events is fraught with peril, as although rare, the particular outcome may be devastating to the individual, both economically and psychologically. Eighteen of the 42 women did not return for on-going treatment suggesting increased contact by clinic staff may be required when oocyte retrieval is not achieved. These data suggest that the failure to collect oocytes after apparently successful ovarian stimulation is rare and random. The information has proved useful in allaying the fears of couples contemplating assisted reproductive technologies.

Temperature change in cryo-containers during short exposure to ambient temperatures.

Times have been defined for the handling of 0.25 ml embryo cryostraws and semen, in either 0.5 ml cryostraws or 1.0 ml cryovials containing 0.5 ml material, before potentially detrimental changes in temperature take place. When handling cryovials the time lag is relatively long, with 78.8 +/- 2.6 s being available to manipulate the vials before -80 degrees C is reached and 335.4 +/- 3. 8 s until the eutectic point (approximately -7 degrees C) is reached. However the situation with cryostraws is less tolerant. Both 0.25 and 0.5 ml versions reach temperatures >-80 degrees C within 40 s, and the eutectic point is reached in 79.0 +/- 2.0 s in 0.25 ml cryostraws. These time/temperature data have proved useful in educating new technicians, as well as clinicians and nurses who may also handle frozen human material, in the need to minimize the ambient temperature exposure time of stored specimens so as to maintain optimal post-thaw viability.

LH 'dipstick' quantitation by reflectance meter.

The introduction of rapid semiquantitative methods using monoclonal antibodies to measure urinary LH has application to the management of the infertile couple. The interpretation of the colour change end-point has however been subjective and thus liable to misinterpretation with resultant problems in clinical management. This short communication describes the use of a modified reflectance meter to overcome these problems.