Effects of visible light and room temperature on the ultrastructure of preimplantation rabbit embryos: a time course study

Abstract

In a time course study (4-20 h) rabbit early cleavage stages (day 1 p.c.) and compacted morulae (day 3 p.c.) were exposed to visible light or room temperature (23 degrees C), respectively. An 8 h light exposure of day 1 embryos caused alterations in nuclear morphology (lobulated nuclei, loss of nucleolar differentiation), an increased electron density of the cytoplasm, and cellular fragmentation leading to a considerable degeneration of blastomeres (central clustering of organelles, loss of cell surface differentiation) after a 20 h exposure. Room temperature exposure (compacted Day 3 morulae) led to decompaction and a cleavage delay after 8 h. After 10 h, arrested metaphases occurred in all examined morulae. Even after 20 h at 23 degrees C, day 3 embryos were at the decompacted morula stage, and showed metaphase-arrested blastomeres. The general morphology of the blastomeres was unaffected at this temperature, except for vacuolated ser- and cis-side vesicles of the Golgi complex at 8, 12 and 20 h, respectively.

Full-Term Development of Golden Hamster Oocytes Following Intracytoplasmic Sperm Head Injection

“…The reason for harmful effects of light on oocytes and embryos is not clear, but generation of radical oxygen species may damage genomic and mitochondrial DNA in oocytes and embryos. Although golden hamster oocytes/embryos may be exceptionally sensitive to light [23,24], possible detrimental effects of light on mammal oocytes and embryos [31][32][33] should be taken into consideration during their manipulation.…”

Effect of embryonic fibroblast cell co-culture on development of mouse embryos following exposure to visible light

“…Similar to mouse oocytes and in contrast to mouse 2-cell embryos (our results), rabbit day 1 embryos are less sensitive to visible light and they may tolerate 8 h exposure to visible light. But rabbit oocytes as well as hamster oocytes are more sensitive to visible light [7]. By comparing the results of different studies on various animals, it can be suggested that the nature of an animal is an influential factor in resistance to visible light.…”

“…On the contrary, in vitro produced embryos as well as oocytes are prone to various environmental factors during manipulations in laboratories [1]. The adverse effects of pH fluctuations [2,3], high and low laboratory temperature [4], change in carbon dioxide and O 2 level [5,6] and light [7,8] have been investigated to some extent. Among the environmental factors, light is known to exert some harmful effects on developmental competence of mammalian oocytes and embryos [9].…”

An increase in [Ca2+]i is sufficient but not necessary for driving mitosis in early mouse embryos

“…Mammalian embryos are susceptible to photodamage by visible light (Daniel, 1964;Hegele-Hartung et al, 1991) and we have previously found that time-lapse confocal microscopy prevents mitosis entry in zygotes in almost all cases (G.F. and J.C., unpublished). Two-photon microscopy uses two-photon excitation of the fluorophore, allowing the use of longer-wavelength light and restricting excitation to the focal point.…”