OCCURRENCE OF A PROTHORACICOTROPIC HORMONE-LIKE PEPTIDE IN THE DEVELOPING NERVOUS-SYSTEM OF THE HONEY-BEE (APIS-MELLIFERA L)

An antibody generated against prothoracicotropic hormone (PTTH) of the silkworm Bombyx mori reacted with distinct sets of cells in the centr al nervous system and also in the retrocerebral complex of Apis mellif era larvae and pupae. Neurons expressing a Bombyx-PTTH-like peptide we re first detected in the spinning stage of the last larval instar. Fiv e distinct clusters of brain neurons comprising a total of 20-24 neuro ns were stained in this larval stage, in addition to a pair of somata located in the labial neuromere and in the first thoracic ganglion. Wi th progressing metamorphosis this pattern changed. In white-eyed pupal brains only two neurons in the dorsal protocerebrum continued to expr ess a PTTH-like peptide, whereas in the suboesophageal ganglion each n euromere now contained a pair of immunoreactive neurons. No axonal PTT H immunoreactivity was detected.