Biomedical subjects

Simon Cooke

Publications and source records attributed to Simon Cooke.

4 recordsLinked to original sources

PubMed2006

Do age and extended culture affect the architecture of the zona pellucida of human oocytes and embryos?

Advanced female age and extended in vitro culture have both been implicated in zona pellucida (ZP) hardening and thickening. This study aimed to determine the influence of (i) the woman's age and (ii) prolonged in vitro culture of embryos on ZP thickness and density using non-invasive polarized light (LC-PolScope) microscopy. ZP thickness and density (measured as retardance) were determined in oocytes, embryos and blastocysts in women undergoing intracytoplasmic sperm injection (ICSI) in two age groups (older, > 38 years; younger, < or = 38 years). A total of 193 oocytes from 29 patients were studied. The younger group contained 100 oocytes and the older group 93 oocytes. The ZP was significantly thicker in metaphase II oocytes in the older group compared with the younger group (mean +/- SD: 24.1 +/- 2.5 microm vs 23.1 +/- 3.3 microm; p = 0.01) but ZP density was equal (2.8 +/- 0.7 nm). By day 2 of culture, embryos from the two groups had similar ZP thickness (22.2 +/- 2.2 microm vs 21.7 +/- 1.6 microm; p = 0.28) and density (2.9 +/- 0.7 nm vs 2.8 +/- 0.8 nm; p = 0.57). For the embryos cultured to blastocyst (older: n = 20; younger: n = 18) ZP thickness was similar in the two groups (19.2 +/- 2.7 microm vs 19.1 +/- 5.0 microm; p = 0.8) but thinner than on day 2. The older group had significantly denser ZP than the younger group (4.2 +/- 0.5 nm vs 3.3 +/- 1.0 nm, p < 0.01). Blastocysts from both groups had significantly denser ZP than their corresponding day 2 embryos (older: 4.2 +/- 0.5 nm vs 2.9 +/- 0.7 nm, p < 0.001; younger: 3.3 +/- 1.0 nm vs 2.8 +/- 0.8 nm, p = 0.013). It is concluded that there is little relationship between ZP thickness and its density as measured by polarized light microscopy. While ZP thickness decreases with extended embryo culturing, the density of the ZP increases. ZP density increases in both age groups with extended culture and, interestingly, more in embryos from older compared with younger women.

Adult↗

PubMed2004

Equivalency of culture media for human in vitro fertilization formulated to have the same pH under an atmosphere containing 5% or 6% carbon dioxide.

Culture media for human in vitro fertilization and early embryonic development were modified to maintain similar pH values under an atmosphere containing 5% or 6% carbon dioxide by adjusting the concentration of sodium bicarbonate. Similar results were obtained with both media groups in a mouse embryo assay and in human in vitro parameters of fertilization and early development and clinical outcomes.

Adult↗

PubMed2002

Improvement in early human embryo development using new formulation sequential stage-specific culture media.

OBJECTIVE: To determine whether altering selected components of sequential culture media can improve early development variables of human embryos. DESIGN: Prospective, randomized, sibling oocyte split trial. SETTING: Private ART center. PATIENT(S): Two hundred eight undergoing treatment with in vitro fertilization or microinjection. INTERVENTION(S): Oocytes from each patient were randomly allocated to fertilization and cleavage media of a control and a trial culture medium formulation. MAIN OUTCOME MEASURE(S): Rates of fertilization, cleavage, and uncontrolled division; average embryo morphology score; blastomeres per embryo; embryo score parameter (number of blastomeres x embryo morphology grade); and embryo utilization. The trial media resulted in a higher fertilization rate, higher cleavage rate, lower rate of uncontrolled division, higher number of blastomeres per embryo, higher average embryo morphology score, a higher embryo score parameter, and higher embryo utilization rate compared to the control media. All differences were statistically significant. CONCLUSION(S): Improved sequential stage-specific culture media can reduce the occurrence of severe human embryo fragmentation and improve developmental variables in early IVF- and ICSI-generated embryos.

Adult↗

PubMed2002

Objective assessments of temperature maintenance using in vitro culture techniques.

PURPOSE: To assess the ability of various facets of embryo culture (microscope stage warmers, volumes of culture media, culture vessel lids, and type of culture incubator) to maintain a constant temperature in vitro. METHODS: Ability to maintain 37.0 degrees C in the microenvironment of gametes was recorded by digital thermocouple in the chosen facets of in vitro culture. RESULTS: Stage warmers are highly variable in their ability to maintain the set temperature (range 33.8 degrees C-37.0 degrees C after 60 s). Temperature loss in culture media is both volume and vessel dependent, and the direct heat transfer culture incubator (MINC) has superior temperature maintenance compared with a large volume air convection incubator (FORMA), where temperature regain from 35.0 degrees C to 37.0 degrees C took 5.5 min compared to >20 min. CONCLUSIONS: There are large measurable differences in the ability to maintain set temperature that depend on the stage warmer used, volume of media, use of vessel lids, and the type of incubator chosen for IVF culture.

Cell Culture Techniques↗