Development-activity relationships in nymphal corpora allata of the cockroach, Diploptera punctata

• Published in: Physiological entomology Vol. 21; no. 4; pp. 268 - 274
• Main Authors: Chiang, A.S, Holbrook, G.L, Schal, C
• Format: Journal Article
• Language: English
• Published: 01.12.1996
• Subjects: biological development; biosynthesis; cell number; cell size; cells; corpora allata; Diploptera punctata; fenoxycarb; hormonal regulation; inhibition; juvenile hormones; mitosis; nymphs; size
• ISSN: 0307-6962; 1365-3032
• DOI: 10.1111/j.1365-3032.1996.tb00864.x

In females of Diploptera punctata the corpora allata undergo a gradual increase in volume during most of the second nymphal stadium. In the first half of the stadium, steady growth of the glands results from a progressive increase in the size of constituent cells. Late in the stadium, cell size declines but the volume of the glands continues to rise due to an increase in cell number. Changes in cell size during the stadium displayed a distinct pattern in relation to Juvenile Hormone (JH) synthesis. Both cell size and activity increased during the first two-thirds of the stadium, peaked early in the last third of the stadium, and decreased before the moult. The rise in cell numbers late in the stadium corresponded to a wave of cellular mitosis and occurred after a steep decline in the rate of JH biosynthesis. Exposure of late second instars to fenoxycarb, a JH analogue, depressed mitosis significantly, suggesting autocrine regulation of cell proliferation in the corpora allata. Possible mechanisms modulating sequential cycles of growth and atrophy of cells and cell proliferation in these glands are discussed in relation to temporal patterns of JH and ecdysteroid titres in nymphs.