(A) The vasa of males during spermiation, shortly after entering a pond, collected early in the March breeding season. The epithelial cytoplasm is dyed a vivid blue, and bundles of spermatozoa are discernible in the lumina.

(B) The vasa of males with a distinctive aquatic-phase morph, collected at the peak of the March breeding season. The epithelial cells have discharged their secretion into the lumina, the cytoplasm has lost its color, and spermatozoa in the lumina are entirely separated from each other.

For comparison, see histological changes in the cloacal region of both these phases (Male Ventral Glands).