Heterologous gap junctions between oocyte and follicle cells in Bufo arenarum: Hormonal effects on their permeability and potential role in meiotic arrest

Abstract

The physiological significance of follicle cell-oocyte gap junctional coupling in the ovarian follicle Bufo arenarum was investigated. Lucifer Yellow injected into the oocyte readily passed to the overlying follicle cells, demonstrating effective dye coupling. We determined that the gap junction coupling varies during the annual sexual cycle. In winter there is a marked decrease in the amount or absence of heterologous gap junction contacts. In contrast, during the breeding season, gap junctions were normally coupled. We studied in vivo and in vitro the effects of frog pituitary hormone (FPH) and follicle stimulating hormone (FSH) on gap junction coupling. The results suggest that FSH induce the coupling of gap junctions enabling a greater metabolic cooperation necessary for oocyte growth and maintenance.On the other hand, nuclear maturation under physiological conditions seemed to have a direct consequence on the gap junction uncoupling and the interruption of the gap junctional flow of an oocyte maturation inhibiti 3n factor by the effects of LH-like gonadotropin or progesterone. 0 1996 Wiley-Liss, Inc.

Ultrastructural observations of previtellogenic ovarian follicles of the caecilians Ichthyophis tricolor and Gegeneophis ramaswamii

“…The zona pellucida and the vitelline envelope appear later (Stifani et al, 1988(Stifani et al, , 1990Aybar et al, 1996;Villecco et al, 1996Villecco et al, , 1999Villecco et al, , 2000. The organization of the previtellogenic follicles in the caecilians almost matches that of the frogs described.…”

“…The fully formed yolk platelet consists of glycogen and lipids, the acquisition of which may follow a different pattern (Villecco et al, 1999;Uribe, 2003). The ultrastructural changes in the follicles in relation to these stages have been described only for a few anuran species Villecco et al, 1996Villecco et al, , 1999Villecco et al, , 2000Villecco et al, , 2002Sanchez and Villecco, 2003). The ultrastructural description of previtellogenic follicles of urodeles and caecilians has not yet been attempted (Uribe, 2003;Exbrayat, 2006).…”

Assembly of ovarian follicles in the caeciliansIchthyophis tricolorandGegeneophis ramaswamii:light and transmission electron microscopic study

“…In addition to this passive role, the follicle cells in other amphibians play an active role in the formation of vitelline envelope (Dumont & Brummet, 1978), steroid biosynthesis (Redshaw, 1972;Guraya, 1979;Wallace, 1985;Mahmoud et al, 2006), providing cAMP, which would be a regulatory molecule in the meiotic arrest of the oocyte at diplotene (Villecco et al, 1996(Villecco et al, , 2000(Villecco et al, , 2002. The production of a maturation inducing hormone (MIH) brings about oocyte maturational competence (OMC) so as to respond to MIH (Villecco et al, 1996;Patino et al, 2001), synthesis and secretion of the components of the vitelline envelope (Cabada et al, 1996). The possible role of the follicle cells in these aspects in the caecilians is under investigation.…”

Ultrastructural changes in the follicular epithelium ofCeratophrys cranwelliprevitellogenic oocytes

“…These include steroidogenesis (Redshaw, 1972;Fortune, 1983;Sretarugsa & Wallace, 1997;Hernandez et al, 2003;Schoenfelder et al, All correspondence to: S.S. Sánchez (Dumont, 1978), meiotic arrest (Villecco et al, 1996) and other processes such as vitelline envelope formation (Dumont and Brummett, 1978;Cabada et al, 1996), RNA transfer (Sanchez Riera et al, 1988;Motta et al, 1995) and organelle transfer (Andreuccetti, 1992;Motta et al, 1995). Follicle cells have been implicated in a number of gonadotrophin-regulated processes involved in oocyte growth and maturation.…”

“…Follicle cells have been implicated in a number of gonadotrophin-regulated processes involved in oocyte growth and maturation. These include steroidogenesis (Redshaw, 1972; Fortune, 1983; Sretarugsa & Wallace, 1997; Hernandez et al ., 2003; Schoenfelder et al ., 2003), initiation of yolk protein (vitellogenin) uptake (Dumont, 1978), meiotic arrest (Villecco et al ., 1996) and other processes such as vitelline envelope formation (Dumont and Brummett, 1978; Cabada et al ., 1996), RNA transfer (Sanchez Riera et al ., 1988; Motta et al ., 1995) and organelle transfer (Andreuccetti, 1992; Motta et al ., 1995).…”