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Results for “MICROMANIPULATION”

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At least 343 records · Page 19Linked to original sources
PubMed1998

Clinical application of new micromanipulative technologies to treat the male.

Traditional treatments of the male have produced no improvement in sperm parameters. Since the rate of normal fertilization rate is significantly lower in these cases after classic in-vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) has become the preferred method of treatment. It has been successfully applied in cases of extreme oligoasthenoteratozoospermia, and obstructive and non-obstructive azoospermia. Cryopreservation of testicular tissue will replace the repeated use of fresh testicular tissue. Full information has to be provided to patients about the frequency (approximately 3%) of sex chromosome and autosomal aberrations in men with extreme oligoasthenoteratospermia. The need for screening for Yq deletions is still under study, and any therapeutic consequences for the newborn child will have to be analysed. The incidence of major malformations in newborn children is approximately 2.5%, i.e. comparable with that of the general population. Screening for de-novo sex chromosome aberrations may be particularly useful for men with sperm counts of < 5 x 10(6) and those with non-obstructive azoospermia.

Adult↗
PubMed1996

Centrifugation of bovine oocytes for nuclear micromanipulation and sperm microinjection.

The reproductive biotechnologies of intracytoplasmic sperm microinjection, nuclear transfer and DNA microinjection require the visualization of cytoplasmic components and nuclei of oocytes and early embryonic cells. Bovine oocytes were matured and fertilized in vitro, and then centrifuged at the germinal vesicle, metaphase II and pronuclear stages and at syngamy. These (n = 536) were examined using light and transmission electron microscopy. The organelles stratified in five distinct zones in a consistent pattern in both oocytes and zygotes, though relative fractions changed in organelle composition after fertilization. These comprised a centripetal lipid zone, below which was a vesicular zone, then a supra-equatorial band of smooth endoplasmic reticulum (SER), a clear zone and a centrifugal mitochondrial zone. Cortical granules were located peripherally, single or clumped together, in the clear and mitochondrial zones. The nuclei were usually found associated with the SER or Golgi membranes, and chromatin was clumped at one pole within the nucleus. The maturation spindles were often located beneath the oolemma in all zones, while the first mitotic spindle was usually located in the clear zone. Some of the oocytes were activated by centrifugation and completed maturation.

Animals↗
PubMed1993

Opening of the mouse zona pellucida by laser without a micromanipulator.

A contact-free laser system is described for ablation of the embryonic mouse zona pellucida using a pulsed excimer 308 nm laser. Effects on further embryonic development were evaluated. Zonae of 8- to 16-cell mouse embryos were either lased (n = 189), zona-drilled with acidified Tyrode's solution (n = 183) or left zona-intact (n = 188). Blastocyst formation (99-100%) was similar in the three groups. Hatching occurred earlier in lased embryos compared to those of the control group. These blastocysts hatched through the laser ablated area. Significantly more embryos were hatching on day 4 in the conventionally drilled group when compared to the laser treated group (50% versus 24% respectively). On day 7 of development, significantly (P < 0.05) more embryos conventionally zona-drilled (37%) were intact than those which were previously laser treated (10%). Abnormal development was also noted in a small group of embryos which were lased just on the outside of the zona in comparison to 1/3 of an embryonic width away from the zona. The current results suggest that apparently precise zona laser ablation with an excimer laser at 308 nm may have potential adverse effects which may only be manifested after a prolonged period of culture past the cavitation stage. However, implantation rates of morphologically normal laser abalated embryos were not impaired when compared to control embryos.

Animals↗
PubMed2005

Contactless micromanipulation of small particles by an ultrasound field excited by a vibrating body.

A method is presented to position and displace micron-sized particles of a diameter between 10 and 100 microm without contact to solid instruments. An ultrasound field is utilized for this purpose. It is excited in a fluid-filled gap between a harmonically vibrating body and a rigid plane surface of an arbitrary other body, e.g., an object slide or a wafer. In this ultrasound field a force field is established, which acts on the particles suspended in the fluid and moves them to certain positions. The advantage of the method is that it is possible to manipulate single particles or many particles in parallel on any surface, for example, on a structured wafer. Theoretical calculations of the force field and experimental results including three principles to displace particles with micrometer accuracy are shown. The method might be used for microassembly or cell manipulation and treatment.

Journal Article↗