Evidence that developmental changes in type III acini in the tick Amblyomma hebraeum (Acari: Ixodidae) are initiated by a hemolymph-borne factor


During feeding, certain cells in the salivary gland type III acini of the ixodid tick Amblyomma hebraeum Koch undergo major developmental changes. We induced many of these changes in the ablumenal interstitial cells (AbIC), adlumenal interstitial cell (AdIC), and f-cells of type III acini, by transplanting the salivary gland of the unfed female to the hemocoel of a feeding female. In transplants, AbICs enlarged and formed a labyrinth of extracellular spaces. Extensions of AbICs pushed into the AdIC. Autophagic vacuoles were common in AbICs. The f-cells also enlarged and developed autophagic vacuoles. Complex interdigitation occurred between the f-cells and the AbIC. In transplants, the labyrinth was not as extensive as that of fed unoperated females or of operated females. The AdIC, AbIC, and f-cells did not undergo as extensive a development in unoperated fed males as the same cells did in unoperated fed females. In males AbICs did not develop an extensive labyrinth, and the f-cells did not develop beyond a secretory phase. No autophagic vacuoles were observed in any of these cells. When male salivary glands were transplanted into feeding females, AdIC, AbICs and f-cells developed an ultrastructure similar to the same cells in female transplants. Cells from salivary glands of unfed females cultured for 2 days in TC medium 199 resembled the same cells from control unfed salivary glands. The selectivity of these changes supports the conclusion that a hemolymph-borne salivary gland development factor initiated this development. © 1988 Elsevier Science Publishers B.V.

Publication Title

Experimental and Applied Acarology