Adults of the wingless bagworm moth, Eumeta variegata, show remarkable sexual dimorphism. Final-instar larvae of the male have invaginated wing discs, whereas those of the female are rudimentary. To determine the best method for culturing the wing discs of E. variegata, which in both sexes are attached to the larval integument, two methods of culturing the larval wing discs are compared. Initially, a stationary culture was used. In these cultures necrotic cells and degeneration of wing discs of males were sporadically observed. By contrast, many small vacuoles were observed in the female wing rudiment under these conditions. In order to overcome some of the problems associated with stationary culture, rotating culture was used and resulted in the wing discs of males and females remaining in good condition. A histological analysis revealed that the wing disc morphology was normal when they were cultured in this way. These results indicate that rotating the culture medium is the better procedure for studying the action of hormones on the differentiation and metamorphosis of reduced wing rudiments in E. variegata.
The growth response to angiotensin II (Ang II) was studied using cultured vascular smooth muscle cells (VSMC) isolated from the aortae of male and female spontaneously hypertensive rats (SHR). Systolic and mean arterial blood pressure of 10-week-old males was significantly higher when compared to age-matched females. The specific growth rate of male VSMC was significantly higher on the third and sixth day after synchronisation. Angiotensin II in concentration 10~7 M stimulated the specific growth rate only in male VSMC during the exponential phase of growth. Moreover, doubling time was 3 hours shorter in male VSMC in comparison with the females. Our results suggest that both the increased specific growth rate and augmented growth-response of male VSMC to Ang II may explain the higher sensitivity of males to hypertensive stimuli.