Immunoglobulin concentrations in pig follicular fluid.

IgG is the predominant immunoglobulin in pig follicular fluid. IgA is present in amounts second to IgG, while IgM is detectable in traces only. The concentration of IgG in the fluid increases as the follicles enlarge to the Graafian preovulatory size, while IgA levels seem not to be affected. Follicular fluid of prepubertal gilts contains slightly higher IgA concentration compared to sow follicular fluid although its IgG content is much less. There is no correlation between the IgG and IgA concentrations in the porcine follicular fluid; this may suggest different rates of filtering of these immunoglobulins into the follicles.