Sources of RNA supply to the oocytes in Crynodes peregrinus fuessly (Coleoptera : Chrysomelidae)

• Published in: International journal of insect morphology & embryology Vol. 8; no. 2; pp. 113 - 122
• Main Authors: Ray, Aparna, Ramamurty, P.S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1979
• Subjects: arthropods; entomology; insects; telotrophic ovariole; 3H-uridine incorporation; autoradiography; trophocytes; RNA synthesis; germinal vesicle; follicle epithelium; Histochemistry
• DOI: 10.1016/0020-7322(79)90010-2
• ISSN: 0020-7322

Histochemical and autoradiographic investigations of the sites of RNA synthesis in telotrophic ovarioles of Crynodes peregrinus were carried out. Oöcyte growth occurs in 4 stages. Stages I and II are previtellogenic stages (euplasmic growth), stage III is vitellogenic while stage IV is a postvitellogenic stage, having chorionated eggs. RNAse-sensitive basophilic reaction is noticeable in follicle epithelial cells, trophocytes, oöcyte cortex and germinal vesicle. 3H-uridine incorporation patterns showed that trophocytes synthesise RNA in their large polyploid nuclei and supply the products to the oöcytes via trophic cords. Follicle cells also synthesise RNA, which, up to early stage III, seems to be exported to the oöcyte, but later, is perhaps retained in the cells for synthesis of chorion precursors. Germinal vesicle is also actively involved in RNA synthesis up to stage II and subsequently this diminishes or ceases completely. This represents an intermediate condition between polytrophic ovarioles where the germinal vesicle is practically idle and panoistic ovarioles, where it actively synthesises RNA throughout. Thus, 3 possible sources of RNA supply to the oöcyte are indicated and all these seem to contribute to its euplasmic growth.