Differentiation and morphogenesis of Triatoma infestans (Klug 1834) female gonads. I- Post embryonic development

The post-embryonic development of the female gonads in Triatoma infestans (Hemiptera, Heteroptera), insects of importance in health affairs as harbors and vectors of different tripanosomatidea flagellates, is presented in a complete follow-up since insect hatches from the egg up to the last molt in the fifth instar stage. The detailed description of the morphological changes which occur in each instar as well as careful measurements evaluating its size increase have been analyzed by stereomicroscopy, phase contrast, dark field, and oblique ilumination, in order to optimize the observations as well the photographic register of gonad morphology and structure. The analysis was performed on gonad specimens obtained from broods no less than twenty (20) nymph bugs, reared at constant temperature and fed-up regularly. According to the results of our study we can assert that gonad differentiation takes place in early phases of the insect development. Such is tge case that first instars nymph´s present absolutely and easily recognizably male and female gonads. From the third instar on beside the filament region, the three zones in each ovariole body is distinguished, a differentiation that is more noticeable during the fourth instar where a definite organization is present at the vitelarium. Such a clear cut zone development continues intensively during the fifth instar. Finally at the end of such fifth nymph stage and when the last molt toward adults is prepared, clear signs of ovariole maturation take place since oocytes in early vitelogenesis are found.

The development of the vitelline envelope during Bufo arenarum oogenesis

La información de la envoltura vitelina del ovocito de Bufo arenarum durante la ovogénesis es estudiada a nviel ultraestructural. Se analizan diferentes estadios del ovocito en desarrollo, desde previtelogénesis hasta ovocitos totalmente desarrollados . Tres períodos pueden definirse en la formación de la envoltura vitelina. El primero se caracteriza por la aparición de un esbozo de aspecto fibrilar. Luego gran número de microvellosidades del ovocito se proyectan e invaden el esbozo inicial, observandose dispersas proyecciones citoplasmáticas desde las células foliculares. El tercer momento se caracteriza por la organización en bandas y fascículos de los elementos fibrilares estructurales, dando lugar a un estado de configuración de la envoltura vitelina muy semejante al que se encuentra en ovocitos celómicos. Los diferentes pasos del proceso de formación de la envoltura vitelina son analizados en función del estado citofisológico de las células involucradas en el proceso. A partir del cuadro observado en ovocitos y células foliculares se llega a la interpretación de que el principal responsable en la formación de la envoltura vitelina es el ovocito