Ultrastructural changes in the follicular epithelium ofCeratophrys cranwelliprevitellogenic oocytes

Abstract

In this work we carried out ultrastructural, autoradiographic and biochemical analyses of the follicular epithelium during C. cranwelli previtellogenesis. This study revealed that the follicular epithelium in early previtellogenesis is constituted of a single layer of squamous homogeneous cells. During mid-previtellogenesis two types of cells develop: dark cells and clear cells. The follicular dark cells are actively involved in the synthesis of RNA, which is transferred to the oocyte through the interface. In late previtellogenesis the dark cells show apoptotic characteristics such as chromatin condensation, DNA fragmentation and cytoplasm shrinkage. This process forms apoptotic bodies that seem to be engulfed by the oocyte. Our results show evidence that, during mid- and late C. cranwelli previtellogenesis, the follicular epithelium undergoes remodelling processes interacting with the oocyte.

Analyses of the development and glycoproteins present in the ovarian follicles of Poecilia vivipara (Cyprinodontiformes, Poeciliidae)

“…We hypothesized that the presence of stratified follicular epithelium in some ovarian follicles indicates their preparation for the next phase of follicular development by increasing the number of epithelial cells, which was confirmed by the presence of these cells during the phases of mitosis in follicular epithelium. Villecco et al (2007) analyzed the follicular epithelium of previtellogenic oocytes of Ceratophrys cranwelli and observed the development of two distinct types of cells: clear and dark ones. The dark cells were actively involved in the synthesis of RNAs, which were transferred to the oocytes and subsequently suffered apoptosis.…”

Gametogenesis and reproductive dynamics of Rhinella schneideri (Anura: Bufonidae): Influence of environmental and anthropogenic factors

“…For tropical anurans, some aspects related to spermatogenesis (Aguiar-Jr, Lima, Bao, & Recco-Pimentel, 2004;Ferreira, Mehanna, & Prado, 2008;Garda, Colli, Aguiar-Jr, Recco-Pimentel, & Báo, 2002;Oliveira, Vicentini, & Taboga, 2003;Oliveira, Zanetoni, & Zieri, 2002;Santos & Oliveira, 2008;Veiga-Menoncello, Lima, & Recco-Pimentel, 2006;Villagra et al, 2014) and oogenesis (Oliveira & Santos, 2004;Prado, Abdalla, Silva, & Zina, 2004;Villecco, Mónaco, & Sánchez, 2007) have already been described. In addition to gamete morphology, anurans have been models for several studies that characterise the reproductive dynamics of the species (Akef, 2014;Ferreira & Mehanna, 2012;Huang, Lin, & Yu, 1997;Jørgensen, 1981;Kanamadi & Saidapur, 1982;Kaptan & Murathanoglu, 2008;Medina, Ramos, Crespo, González-Calvar, & Fernández, 2004;Sasso-Cerri, Faria, Freymüller, & Miraglia, 2004;Villagra et al, 2014).…”