Two types of frontal glands inDiphyllobothrium dendriticum (Cestoda, Pseudophyllidea) and their fate during the maturation of the worm

Two types of frontal glands were detected in plerocercoids ofDiphyllobothrium dendriticum and their fates during the development from plerocercoid to adult worm were followed. Type I—the green glands—dominate the scolex of the larvae. They are located posteriorly and peripherally in the scolex and in the cortical and medullary parenchyma of the neck. The glands empty into the frontal pit. Type II—the golden glands—have earlier eluded observation or been mingled with the green glands. The golden glands are confined to the scolex and are closely associated with the nervous system. The green glands are activated during the first day of cultivation in vitro and in vivo. Already after 12 h of cultivation most of the green gland material has been secreted. The process continues, rapidly emptying ducts and cells. The green glands disappear completely within three days. The golden glands remain, on the whole, unaltered throughout the maturation of the worm and still occur in the adult worm. The roles of the two glands are discussed.