Morphological and physiological studies of the silkmoth ovary I. The general histology and some histochemical properties of the ovary of Samia Cynthia (Drury).

Ovaries of the giant silkmoth Samia cynthia Drury have been studied histologically and histochemically during diapause, adult development, and after injury to the diapause animal. In addition to cellular changes involved in follicular growth and vitellogenesis, changes in the intermediate layer cells are very striking, showing a distinct pattern during ovarian development and after injury. Two types of granules, one periodic acid-Schiff (PAS) positive, the other paraldehyde-fuchsin (PF) positive, change in their number and distribution in the intermediate cells during development and after injury. The PAS-positive granules appear during the first one-third of development, increase in number and size until the tenth day, then gradually dwindle in number and size, and disappear in the adult cells. The PF-positive granules, present in moderate numbers in the diapause animal, decrease in number until the tenth day of adult development, then reappear, and are present again in adult intermediate cells. After injury to a diapause pupa, intermediate cells show a greatly increased number of PF-positive granules, but none that are PAS-positive. The PAS-positive granules are a neutral or mildly acidic mucosubstance, and may correspond to lysosomal activity, while the PF-positive granules may be a neurosecretory-like substance or the product of hormone-dependent protein synthesis, since the patterns of granule distribution in the intermediate cells seem to reflect both general metabolic and hormone-related events.