Conventional methods of semen preparation for IVF, such as swim-up sedimentation, regular Percoll gradients, are not very effective in the treatment of severe oligoasthenozoospermia (total motile count less than 5 X 10(6)). For these cases, a new method of sperm preparation consisting of a reduced volume of a discontinuous Percoll gradient (mini-Percoll) has been utilized. The results obtained were analysed by comparing mini-Percoll versus resuspension in two groups of patients with severe male factor infertility. In the mini-Percoll group, a statistically significant improvement (P less than 0.001) was obtained in the post-treatment seminal parameters of motility, progression and proportion of normal forms. In the resuspension group (n = 12), only eight of 108 oocytes inseminated were fertilized (7%), while in the mini-Percoll group (n = 29), 124 out of 336 oocytes were fertilized (40%) (P less than 0.001). Furthermore, in the mini-Percoll group, a higher pregnancy rate (25 versus 7%) and low abortion rate (22 versus 33%) were observed. Although more studies are necessary to confirm these preliminary data, mini-Percoll seems to be a valid laboratory tool for semen samples of extremely poor quality.
Various microsurgical procedures at the cellular and subcellular levels using laser non-touch techniques are presented and reviewed. In these procedures, the beams of light, varying in their wavelength (range: 14 ns to continuous wave), were directed via microscopes towards the target area. Micromanipulation of human spermatozoa with a laser-generated optical trap enabled the assessment of possible effects on sperm motility and measurements of the relative force generated by each single spermatozoon. Furthermore, the optical trap also provides a new approach to the measurements of intracellular forces without physically touching the cell or its organelles, and inducing chromosome movement during cell division is also possible. Laser beams in a specific configuration are able to induce minimal superficial damage to the zona pellucida of oocytes from various species. This manipulation is aimed at increasing the fertilization rate following insemination with low-quality spermatozoa. Another intracellular application of the laser beams is the destruction of extra pronuclei in polyspermic fertilized human oocytes. These procedures require special equipment which is not commonly available. However, simpler devices may be developed if the advantages of this novel technology are demonstrated.
Long-term exposure of sexually mature female rhesus monkeys (Macaca mulata) to thrice weekly injections of delta 9-tetrahydrocannabinol resulted in a disruption of menstrual cycles that lasted for several months. This period was marked by an absence of ovulation and decreased basal concentrations of gonadotropin and sex steroids in the plasma. After this period, normal cycles and hormone concentrations were reestablished. These studies demonstrate that in rhesus monkeys subjected to long-term treatment with delta 9-tetrahydrocannabinol tolerance develops to the disruptive effects of the drug on the menstrual cycle.
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