Step 1: Understanding the Concept:
The Copper-T (CuT) is a type of non-hormonal Intrauterine Device (IUD).
IUDs are devices inserted into the uterus by medical professionals to provide long-term, reversible contraception.
Step 2: Detailed Explanation:
The Copper-T acts on multiple levels to prevent fertilization:
1. Increased Phagocytosis: The presence of an IUD (a foreign body) in the uterine cavity causes a local inflammatory response. This stimulates white blood cells to increase the phagocytosis (engulfing and digesting) of sperms that enter the uterus.
2. Copper Ion Release: The copper wire on the device continuously releases copper ions (\( Cu^{2+} \)) into the uterine and tubal fluids.
3. Sperm Motility Suppression: These copper ions act as a spermicide. They significantly reduce the motility (swimming speed) and the fertilizing capacity of the sperm. If the sperm can't reach the egg or can't penetrate it, pregnancy is prevented.
4. Implantation Interference: While less common, the device also alters the uterine lining (endometrium), making it hostile for a fertilized egg (blastocyst) to implant.
Comparing with other options:
(a) Preventing ovulation: This is how hormonal pills (OCPs) work by suppressing FSH and LH.
(b) Acidic medium: The vagina is naturally acidic, but the IUD works through ion toxicity, not pH change.
Step 3: Final Answer:
The primary mechanism of the Copper-T IUD is the release of copper ions which increase sperm phagocytosis and inhibit sperm motility.