Journalartikel

Jahr der Veröffentlichung: 1998

Seiten: 125-135

Zeitschrift: Zygote: The Biology of Gametes and Early Embryos

Bandnummer: 6

Heftnummer: 2

ISSN: 0967-1994

DOI Link: https://doi.org/10.1017/S0967199498000045

Verlag: Cambridge University Press

Abstract: 
The dorsoventral polarity of unequally cleaving spiralian embryos becomes established at an early stage. The factors determining the position of the dorsoventral axis are still unknown. We present data showing that the sperm entry point (SEP) in both normal development and under experimental conditions determines the position of the first cleavage furrow in Dreissena embryos. The position of the spindles at second cleavage is directed by the site of fertilisation also, and the large, dorsal D quadrant of the 4-cell stage always forms opposite the SEP. The spiral chirality at third cleavage seems to be independent of both the fertilisation point and the arrangement of the quadrants. Dextral and sinistral third cleavages are found in a single egg batch, but sinistral cleavages prevail. We postulate that two factors coordinate the groper positioning of the dorsoventral axis. The sperm entry point as an epigenetic factor determines the dorsal side of the embryo. But since the dorsoventral axis forms oblique to the first cleavage furrow, this first decision is still ambiguous, and a second decision is required that, due to the alternative chirality of spiral cleavage, finally sets up the dorsoventral axis.

Harvard-Zitierstil: Luetjens, C. and Dorresteijn, A. (1998) The site of fertilisation determines dorsoventral polarity but not chirality in the zebra mussel embryo, Zygote: The Biology of Gametes and Early Embryos, 6(2), pp. 125-135. https://doi.org/10.1017/S0967199498000045

APA-Zitierstil: Luetjens, C., & Dorresteijn, A. (1998). The site of fertilisation determines dorsoventral polarity but not chirality in the zebra mussel embryo. Zygote: The Biology of Gametes and Early Embryos. 6(2), 125-135. https://doi.org/10.1017/S0967199498000045