Oxygen Tension on Human Embryonic Development

The oxygen transport physiology of sand snail Polinices sordidus egg masses was investigated using oxygen microelectrodes and open-flow respirometry. P. sordidus eggs are laid in a jelly matrix that rapidly absorbs water and swells into a horseshoe-shaped sausage. The average diameter of these sausages is 37 mm. Eggs are enclosed in capsules that are distributed throughout the jelly matrix, but 65 % of the eggs are located within 3 mm of the outer surface. There is no circulatory or canal system within the matrix so all gas exchange between developing embryos and the environment must occur by diffusion through the jelly matrix. Oxygen tension in the outer layer remains moderately high (PO2>10 kPa) throughout incubation but decreases rapidly in more centrally located regions, so that by day 4 embryos in this region are exposed to extremely hypoxic conditions (PO2<1 kPa). This hypoxia limits oxygen consumption of embryos to low levels and appears to slow embryonic development or even to arrest it. From day 4 onwards, the central region gradually become less hypoxic because the hatching of peripherally located embryos causes the outer layers of the jelly matrix to disintegrate and thus reduces the diffusion distance for oxygen between the centrally located embryos and the surrounding sea water. As the oxygen tension rises, development accelerates and the embryos eventually hatch as viable veligers, apparently unharmed by their prolonged exposure to hypoxia.

Download Full-text

Morphokinetic Analysis of Preimplantation Development of Mouse Oocytes Fertilised in Vitro Using a Non-humidifying Incubator With Time-lapse Cinematography (CCM-iBIS)

10.21203/rs.3.rs-142391/v1 ◽

2021 ◽

Author(s):

Hiroyuki Watanabe ◽

Haruka Ito ◽

Ayumi Shintome ◽

Hiroshi Suzuki

Keyword(s):

Embryonic Development ◽

Oxygen Tension ◽

Developmental Rate ◽

Time Lapse ◽

Preimplantation Development ◽

Mouse Oocytes ◽

Lower Oxygen ◽

Developmental Rates

Abstract Preimplantation development of mouse oocytes fertilised in vitro was assessed in a non-humidified incubator with time-lapse cinematography (CCM-iBIS). The developmental rates of embryos to the 4-cell and blastocyst stages under 5% CO2, 5% O2, and 90% N2 in CCM-iBIS were significantly higher than those under 5% CO2 in air in CCM-iBIS and a conventional CO2 incubator (CPO2-2301). The developmental speed of embryos was much faster in those cultured under lower oxygen tension in CCM-iBIS than in higher oxygen tension in CCM-iBIS and CPO2-2301. Embryonic development was much faster and more synchronised under lower oxygen tension. Non-humidified culture did not affect the development of the embryos. Mouse embryos cultured at lower oxygen tension reached 2-cell at 17 h, 3-cell at 39 h, 4-cell at 40 h, initiation of compaction at 58 h, morula at 70 h, and blastocyst at 82 h after insemination on average. Although compaction partially unravelled with cell division in compacting embryos, it appeared to complete depending on the timing of observation. Observation at a conventional 24-h interval 13 likely misjudges the developmental rate to morula. Determination of embryonic development 72 h after insemination may be more appropriate for “compacting morula” rather than “morula” in mice.

Download Full-text

Live Confocal Analysis of Fertilization and Early Development

Microscopy and Microanalysis ◽

10.1017/s1431927600031135 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 1012-1013

Author(s):

Uyen Tram ◽

William Sullivan

Keyword(s):

Drosophila Melanogaster ◽

Embryonic Development ◽

Real Time ◽

Early Development ◽

Fluorescent Probes ◽

Primary Defect ◽

Fluorescent Analysis ◽

Dynamic Event ◽

Enormous Amount ◽

Fluorescent Studies

Embryonic development is a dynamic event and is best studied in live animals in real time. Much of our knowledge of the early events of embryogenesis, however, comes from immunofluourescent analysis of fixed embryos. While these studies provide an enormous amount of information about the organization of different structures during development, they can give only a static glimpse of a very dynamic event. More recently real-time fluorescent studies of living embryos have become much more routine and have given new insights to how different structures and organelles (chromosomes, centrosomes, cytoskeleton, etc.) are coordinately regulated. This is in large part due to the development of commercially available fluorescent probes, GFP technology, and newly developed sensitive fluorescent microscopes. For example, live confocal fluorescent analysis proved essential in determining the primary defect in mutations that disrupt early nuclear divisions in Drosophila melanogaster. For organisms in which GPF transgenics is not available, fluorescent probes that label DNA, microtubules, and actin are available for microinjection.

Download Full-text