Fig. 5. Blood ecdysteroid levels and expression of pre-ecdysis-triggering hormone (PETH), ecdysis-triggering hormone (ETH) and their precursors in Inka cells during the last larval instar. (A-C) Throughout the fifth instar, PETH levels were higher than those of ETH and their precursors. (A,B) Differences in levels between PETH and ETH were very obvious during the feeding stage on days 1–4, when only 6–28 % of the total ETH immunoreactivity (ETH-IR) was active ETH and the remaining 72–96 % was represented by different unprocessed precursor forms. (B) Levels of ETH and its precursors increased after the pre-wandering steroid peak. (C) Both active peptides and their precursors reached their highest levels after the prepupal peak, when 54–63 % of the total ETH-IR represented ETH. Each peptide determination represents the mean + S.D. of 3–4 sets of 20–40 epitracheal glands. Each ecdysteroid determination represents the mean ± S.D. of 5–11 haemolymph samples. Note the differences in scale between A, B and C.
