R.H. Asch

High fecundity of amenorrhoeic women in embryo-transfer programmes

There is uncertainty over whether the steady decline in human fertility with increasing maternal age is due to quality of the oocyte or of the endometrium. To clarify the issue age-related implantation and pregnancy rates in two embryo-transfer programmes were examined in relation to embryo quality and type of menstrual cycle. In both the UK and the US programmes rates were higher in previously amenorrhoeic (acyclic) women than in eugonadal women, irrespective of age and number of embryos replaced. Oocyte quality, as determined by age of oocyte donor, in-vitro growth of embryo, and proportion of defective embryos in culture, did not contribute to the difference, nor did type of cycle during therapy. If a uterus that has not been subjected to regular menstrual cycles is a favourable factor, a period of induced amenorrhoea might be beneficial for infertile women.

Movement characteristics of human epididymal sperm used for fertilization of human oocytes in vitro

Study Objective To develop mathematical models using kinematic parameters from Computer-Aided Sperm Analysis (CASA) that predict the fertilization rate of sperm recovered from the caput epididymidis and to test the hypothesis that fertilization was enhanced by the presence of specific sperm subpopulations in the inseminate. Setting In vitro fertilization (IVF) program. Patients Thirteen patients with congenital absence of the vas deferens provided epididymal sperm for IVF as well as for CASA. Results The mathematical model that was most predictive of fertilization rates included kinematic parameters of the epididymal aspirate (percent motility), the inseminate used for IVF (curvilinear velocity [VCL]), and the change in sperm movement after in vitro processing by the mini-Percoll technique (difference in amplitude of lateral head displacement [ALH]). Multivariate cluster analysis revealed that inseminates that resulted in higher fertilization rates had subpopulations of sperm that were characterized by high VCL and high mean angular displacement, as well as a greater change in ALH after processing. Conclusion In vitro fertilization with epididymal sperm was more likely to succeed when the sperm population that was initially aspirated had a higher proportion of motile cells and when these sperm were capable of capacitation in vitro as indicated by the appearance of sperm subpopulations with motility that resembled hyperactivation.

MICROSCOPE-DELIVERED ULTRAVIOLET-LASER ZONA DISSECTION - PRINCIPLES AND PRACTICES

Journal of Assisted Reproduction and Genetics, Vol. 9, No. 6, 1992 LASER Microscope-Delivered Ultraviolet Laser Zona Dissection: Principles and Practices INTRODUCTION amounts of water, we searched for laser systems emitting radiation where water is characterized by relatively high absorption. While other researchers have elected to pursue wavelengths of high absorption coefficient (8) and have recently reported alternative methods for de- livering these particular laser pulses to the zona target by either using glass micropipettes filled with positive air pressure (with the 193-nm radiation) (9) or using specialized fibers or micropipettes (in the case of the 2.94-txm erbium:YAG laser) (10), we have chosen to focus our attention on other wave- lengths. Possible difficulties with contact methods such as energy delivery to the target, the need for making use of a glass or salt-based instrument (some of them are toxic), and the necessity for maintaining physical contact between the delivery media (pipette or fiber) defeat most of the advan- tages in using laser light and essentially reduce the laser-based techniques to a mechanical/contact mode, similar to conventional PZD methods. Addi- tional complications arise from the need for steril- ization of optical fibers or micropipette tips. This requires constant adjustments in the delivery sys- tem and disposal of relatively expensive fiber seg- ments. The tip quality must also be carefully con- trolled in order to achieve a good beam quality, a consideration which is sure to slow down the pro- cedure. A final problem is due to the fact that some laboratories make extensive use of mineral oil cover over the targeted medium. As we discovered, drop- lets of oil tend to adhere to optical fibers when they are inserted through the oil layer into the host me- dium. These oil droplets, in turn, absorb the fiber output radiation, accumulate heat, expand (thereby mechanically disturbing the micromanipulated ob- ject), and completely block any additional radiation from arriving at its target. Based on the above considerations, we have elected to search for a set of laser parameters which will allow the laser light to be delivered to the Since their introduction, the techniques of zona drill- ing (ZD) and partial zona dissection (PZD) have drawn considerable attention as potential tools in gamete and embryo micromanipulation. ZD in- volves the application of small volumes of acidic Tyrodes medium, which, through its digestive properties, creates small holes in the zona pellu- cida (ZP). This process was originally described by Gordon and Talanski (1). PZD is a mechanical tech- nique for breaching the ZP and was first described by Malter and Cohen (2). It makes use of a pointed micropipette which pierces the ZP and is then sheared against a larger pipette, thus creating a breach in the zona pellucida. Indeed, most cur- rently accepted methods of micromaniputation of oocytes and embryos are based on the use of me- chanical techniques or the use of an acidified me- dium solution (3,4). In 1989, Tadir et al. (5) suggested the incorpora- tion of laser technology to achieve accurate inci- sions in the ZP as well as sperm micromanipulation through the use of optical traps. In addition, laser- induced selective destruction of extra pronuclei was also attempted (6). In these studies, the inter- action of the fundamental wavelength Q-switched Nd:YAG laser (15-nsec pulses of 1.064 ixm), the Nd:YAG harmonics (at 532 and 355 nm), and a nitrogen-pumped dye laser (600-psec pulses, at 366 nm) were all tested. In an effort to determine the most suitable param- eters for selective laser interaction with the various components within oocytes and embryos, we have been studying additional laser systems (7). Since cells in general, and oocytes and embryos in par- ticular, are relatively transparent and contain high The opinions presented in this column are those of its author(s) and do not necessarily reflect those of the journal and its editors, publisher, and advertisers,

Penetration of zona-free hamster oocytes using human sperm aspirated from the epididymis of men with congenital absence of the vas deferens: comparison with human in vitro fertilization *

OBJECTIVES To assess the ability of sperm aspirated from the epididymis of men with congenital absence of the vas deferens to penetrate zona-free hamster oocytes. To directly compare the performance of human epididymal sperm in the zona-free hamster oocyte sperm penetration assay (SPA) with the results of human in vitro fertilization (IVF). DESIGN Sperm penetration assay was carried out with epididymal sperm retrieved microsurgically, and with ejaculated sperm obtained from fertile donors (internal controls). For direct comparison, SPA was performed with the same epididymal sperm sample used for IVF. PATIENTS, PARTICIPANTS Men with congenital absence of the vas deferens undergoing sperm aspiration as part of their infertility treatment and control donors who provided ejaculated sperm. RESULTS Epididymal sperm penetrated SPA with a score of 0% to 30%. The SPA scores for internal controls using ejaculated sperm was 30% to 71%. Linear regression analysis of the association between penetration scores in SPA and fertilization rate in IVF indicated a positive correlation that was highly significative. CONCLUSIONS These findings using SPA confirm previous reports on the fertilizing potential of human epididymal sperm and its ability to produce normal pregnancies. The good correlation between SPA and human IVF using epididymal sperm suggest that SPA is an excellent bioassay to test laboratory experimental conditions for improving fertilizing capacity of human epididymal sperm.

Laser zona dissection using short-pulse ultraviolet lasers

The interaction of pulsed ultraviolet radiation with the zona pellucida of human oocytes which had failed to fertilize in standard IVF cycles, was investigated. Two lasers were studied: a 100 ps pulsed Nd:YAG with a nonlinear crystal emitting light at 266 nm, and a 15 ns XeCl excimer laser with 308 nm radiation. Incisions in the zona were made by aiming the beam tangentially to the oocyte. The results indicate superior, high precision performance by the excimer laser creating trenches as narrow as 1 micrometers and as shallow as 1 micrometers . The incision size was found to be sensitive to the lasers energy and to the position of the microscopes objective focal plane, but relatively insensitive to the laser pulse repetition rate. Once the minimum spot size was defined by the system parameters, the laser beam was used to curve out any desired zona shape. This laser microsurgery technique as applied to partial zone dissection or zona drilling could prove very useful as a high-precision, non-contact method for treatments of low fertilization rate and for enhancing embryo implantation rates in patients undergoing IVF treatments.