probe

1. a slender, flexible instrument designed for introduction into a wound or cavity for purposes of exploration. v 2. to use such an instrument.

Molecule used to locate another molecule.

1. a long, slender instrument for exploring wounds or body cavities or passages.
2. a radiolabeled DNA molecule such as a phage, viral or plasmid carrying a foreign DNA sequence used in hybridization to detect DNA homologous to the fragment.

• cryosurgical p. — see cryoprobe.
• electroejaculation p. — a probe containing electrodes which is inserted in the rectum of the male animal and connected to an electrical power source to stimulate the nerves controlling emission and ejaculation of the semen.
• freezing p. — see cryosurgery.