Ultrastructure of the prothoracic gland of variously aged female pupae of Xyleborus ferrugineus and associated ecdysteroid titers.

The prothoracic glands of female pupae of Xyleborus ferrugineus at three ages (0-h, 48-h, and 72-h-old) were examined for ultrastructural changes that correlate with high titers of ecdysteroids in the entire pupa. In all three ages, the prothoracic gland cells appear compact with a prominent nucleus. Lysosome-like structures with concentrically oriented internal membrane are observed in both 0-h and 72-h-old gland cells. Mitochondria are abundant in the glands of both ages, and rough endoplasmic reticulum is relatively sparse. Numerous microtubules are present in the prothoracic gland cells of 48-h-old female pupae that contain relatively high titers of ecdysteroids. Rough endoplasmic reticulum also is especially abundant at this age of the pupa. Ecdysone titers, estimated by the radioimmunoassay method (RIA), were 161.04 +/- 26.80 pg/mg, 704.25 +/- 69.02pg/mg and 298.72 +/- 26.80pg/mg body weight in 0-h, 48-h and 72-h-old female pupae, respectively.