(In the ovule) an opening in the integuments through which the pollentube may enter the seed and through which the radicle usually emerges during germination.
A little opening in the integument which forms the outer layer of an ovule or a seed. The pollen tube enters the ovule through this opening.
An opening in the integuments surrounding the ovule through which the pollen tube may enter the ovule and through which the root emerges upon germination of the seed.
The opening in the ovum for entrance of the spermatozoon. It is seen in the ova of some animals.