from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The entry of several sperm into one ovum during fertilization.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The penetration of an ovum by more than one sperm
from the GNU version of the Collaborative International Dictionary of English
- n. Fullness of sperm, or seed; the passage of more than one spermatozoön into the vitellus in the impregnation of the ovum.
from The Century Dictionary and Cyclopedia
- n. Impregnation of an ovum by more than one spermatozoön.
Sorry, no etymologies found.
If more than one sperm penetrates an egg a situation called polyspermy, an abnormal embryo results, which would not survive.
Occasionally a second spermatozoön may enter the yolk, thus giving rise to a condition of polyspermy: when this occurs the ovum usually develops in an abnormal manner and gives rise to a monstrosity.
The ovum's zona pellucida is modified tot block polyspermy.
Dr Hasson said: 'To avoid the fatal consequences of polyspermy, female reproductive tracts have evolved to become formidable barriers to sperm.