Biomedical subjects

D Imoedemhe

Publications and source records attributed to D Imoedemhe.

5 recordsLinked to original sources

PubMed1992

Fertilization and embryonic development of human oocytes after cooling.

Injury to living cells resulting from rapid cooling to temperatures at or near 0 degrees C has long been recognized, and the phenomenon, which is termed 'cold shock', has been known to occur in some mammalian gametes. Although human embryos have been successfully stored at low temperatures, cryopreservation of the human oocyte is proving to be more difficult. Whether or not this lack of success is a direct result of cellular injury brought about by 'cold shock' is the purpose of the current investigation. Human oocytes were cooled, in the absence of cryoprotectants, at two different cooling rates (-3 degrees C/min and -1000+ degrees C/min) to a temperature of 0 degrees C and rewarmed prior to insemination. In both cases fertilization after cooling was similar to the rates achieved in a routine in-vitro fertilization and embryo transfer procedure. After cooling at -3 degrees C/min, the rate of fertilization was 19/22 (86%) and after cooling at -1000+ degrees C/min, 9/9 (100%), with non-cooled control rates of 62/87 (71%) and 35/50 (70%) respectively. Fertilized oocytes from both groups were successfully cultured for a further 24 h before termination of the experiment.

Cryopreservation↗

PubMed1988

Osmotic response of oocytes using a microscope diffusion chamber: a preliminary study comparing murine and human ova.

The hydraulic conductivity (Lp) of the plasma membrane determines how cells respond to the stresses of dehydration encountered during cryopreservation. We have used a microscope diffusion chamber which allows for direct real-time observation of the dynamic osmotic response of individual cells in microvolume suspension to compare the Lp of murine and human unfertilized ova. In this system, the response of an individual cell to the induced osmotic imbalance is documented via a series of photomicrographs or videotape; from these data the Lp can be computed. Donated human preovulatory oocytes were compared with macroscopically normal human ova, 43 hr after insemination, which had failed to fertilize (Ff) and with murine ova collected 13 hr post human chorionic gonadotropin injection. The permeability coefficients were 0.65 +/- 0.43, 0.84 +/- 0.39, and 0.36 +/- 0.07 micron3/micron2/atm/min. The results suggest that it may be possible to use Ff ova for experiments to design suitable cryopreservation procedures.

Animals↗

PubMed1987

Attempts to stimulate multiple follicular growth for IVF by administration of pulsatile LHRH.

Administration of pulsatile LHRH (14.4 microgram/pulse per 90 min) from day 5 to 9, or day 7 to 11 of the cycle following clomiphene pretreatment on days 2-6 induced multiple follicular growth for oocyte recovery for in vitro fertilisation. Administration of LHRH without clomiphene pretreatment failed to induce multiple follicular development. The same group of patients treated with clomiphene alone had fewer numbers of mature follicles, fewer oocytes recovered and less pre-embryos for transfer than when treated with clomiphene and LHRH in combination. Peak gonadotrophin release following commencement of LHRH was seen within the first 24 h of administration with a gradual fall in both LH and FSH toward baseline pretreatment values by the fourth day of administration. A discernible LH increment to LHRH was still present on the fourth day of LHRH treatment, but in many individuals no FSH increment was observed. The preovulatory oocytes recovered were predominantly mature with fertilisation rates of 70% and 85.7% for the two regimens. No pregnancy occurred in the six patients who underwent pre-embryo transfer.

Adult↗

PubMed1986

Stimulation of multiple follicular growth for in vitro fertilization by administration of pulsatile luteinizing hormone-releasing hormone during the midfollicular phase.

Pulsatile subcutaneous administration of LH-RH (14.4 micrograms/pulse/90 minutes) during the midfollicular phase (days 7 to 11) of the cycle induced significant increases in circulating LH, FSH, and E2 in all eight women treated. When CC (150 mg/day on days 2 to 6) was administered prior to the LH-RH, multiple follicular development occurred, five to seven mature follicles (greater than 16 mm) being found on day 12 of the cycle. The administration of pulsatile LH-RH in this manner may prove to be an additional regimen for use in IVF programs.

Adult↗

PubMed1986

Follicular fluid alpha 1-antitrypsin--correlation with fertilizing capacity of oocytes.

Follicular fluid and serum concentrations of alpha-antitrypsin (alpha 1-AT) were determined by radial immunodiffusion in 72 samples obtained from 33 infertile women undergoing in-vitro fertilization and embryo transfer. A statistically significantly lower concentration of alpha 1-AT was found in follicular fluids from which mature oocytes were recovered (mean 1.52, SE 0.06 g/l) than in those yielding immature oocytes (mean 2.96, SE 0.22 g/l). There was also a significantly higher rate of fertilization (85%) for oocytes from follicular fluids with alpha 1-AT concentrations of less than or equal to 2.0 g/l than for those obtained when the alpha 1-AT concentration was greater than 2.0 g/l (only 25%). The mean follicular fluid alpha 1-AT concentration (1.52, SE 0.06 g/l) of follicles yielding mature oocytes was significantly lower than the relevant mean serum concentration (3.17, SE 0.10 g/l). There was, however, no significant difference between follicular and serum concentration of alpha 1-AT in the group yielding immature oocytes or in the serum concentrations between the different oocyte maturity groups. The measurement of follicular alpha 1-AT may be a useful adjunct in predicting which oocytes are mature and likely to be fertilized.

Adult↗