Final answer:
Dimeric IgA is an antibody important for immune defense on mucosal surfaces, produced by exocrine glands, and transferred from mother to infant through breast milk.
Step-by-step explanation:
Dimeric IgA plays a crucial role in the immune system by protecting bodily surfaces against pathogen invasion. It is produced by exocrine glands and found in secretions such as mucus, saliva, tears, and notably in mother's breast milk, known as colostrum. Dimeric IgA is composed of two IgA monomers linked by a J chain and a secretory component, enabling its protection not just within the body but also on the mucosal surfaces. This form of IgA helps in trapping pathogens in mucus which can then be eliminated from the body, playing a vital role in immunity especially in infants who receive this protective antibody through breastfeeding.