Fat body, gonad, and prothoracic gland fate in Blattella germanica adults (Blattaria, Blattellidae)

• Published in: The Italian journal of zoology Vol. 67; no. 3; pp. 245 - 254
• Main Authors: Lambiase, Simonetta, Conforti, Elena, Fasola, Mauro, Grigolo, Aldo, Zhang, Yingmei
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.01.2000
• Subjects: Age-related degeneration; Bacteriocytes; Blattella germanica; Cockroaches; Fat body; Gonads; Hormonal control; Prothoracic gland
• ISSN: 1125-0003; 1748-5851
• DOI: 10.1080/11250000009356319

The histological analysis of the fat bodies, gonads, and prothoracic gland of both sexes of Blattella germanica, carried out throughout their adult life, revealed different fates of these structure in the two sexes. In the males, the prothoracic gland and the fat bodies showed a precocious alteration while the testicular morphology was preserved until two months of adult life. In the females, instead, the prothoracic gland persisted slightly longer and the fat body and ovary do not show alterations until after two months of adult life. Moreover, while the histological alterations found in the males were uniformly diffused, in females the occurrence of alterations was scattered in the fat body lobes and ovarioles. The amount of bacteriocytes was initially higher in females than in males; later, however, bacteriocytes decreased precociously in males, whereas in females they decreased only after the synthesis phase of vitellogenins. Such synthesis could be ascribed not only to the fat bodies, but also to the bacteriocytic component. The numerical decrease of bacteriocytes in both sexes is due to cellular degeneration with consequent loss of the symbiotic complement. We suggest that the preservation, over time, of the fat body morphology and of the bacteriocytic component in the female can be attributed to the synthesis of ecdysteroids, which are initially secreted by the prothoracic gland and later by the ovaries.