Immunological responses and microorganisms indigenous to the gastrointestinal tract.

Age Factors Animals Animals, Newborn Antibodies, Bacterial/biosynthesis Antibody-Producing Cells Antigen-Antibody Reactions Antigens, Bacterial Bacteria/immunology Bacteroides Digestive System/microbiology Female Germ-Free Life Immunity Immunoglobulins Intestinal Secretions/immunology Mice Pregnancy Spleen/cytology,immunology

Antibodies, Bacterial Antigens, Bacterial Immunoglobulins