Analysis ofBufo arenarumoviductal secretion during the sexual cycle

Abstract

SummaryBufo arenarum oocytes are oviposited surrounded by jelly coats, one component of the extracellular matrix required for fertilization. The secretion, released to the oviductal lumen, was analysed by SDS-PAGE. The coomassie blue staining evidenced an electrophoretic pattern with molecules ranging between 300 and 19 kDa that showed variations in their secretion profiles during the sexual cycle. In the preovulatory period the densitometric analysis showed the presence of nine peaks with marked predominance of the 74 kDa molecule. Once ovulation has occurred, the jelly coats become arranged around the oocytes during their transit throughout the oviductal pars convoluta (PC), revealing the addition of three proteins only observed during this period, which suggests a differential secretion. Some of these proteins could not diffuse under any extraction treatment, indicating for them a structural or in situ function. Proteins of low molecular mass diffused totally while others showed a partial diffusing capacity. After ovulation a marked decrease in the relative amount of all the proteins released to the lumen, especially the 74 kDa protein, could be detected. During this period, unlike the other stages of the sexual cycle, a differential secretion pattern was observed along the PC. The histochemical analysis performed during the ovulatory period showed the presence of glycoconjugates including both acidic and neutral groups. The present results are in agreement with previous ultrastructural and histochemical studies that describe the role of Bufo arenarum jelly coats in fertilization.

Homeostasis and secretion of calcium in the oviductal mucosa of toad Rhinella arenarum

“…After the transit of the oocytes through the PC, the immunoanalysis revealed a decrease in the marking of the proteins analyzed. This is evident in the SC of the two layers and correlates with the histological analysis that indicating a decrease in the number and volume of the SC (Crespo et al, ) with a concomitant decrease in the secretory activity (Crespo et al, ). TEM observation revealed that during this period there is a marked reduction in intracellular Ca 2+ deposits mainly distributed in the vicinity of the plasmatic membrane.…”

“…In the glandular layer, we can also see heterogeneous distribution of reactivity that at this level does not involve individual cells but whole glands, most of them immunopositive. The presence or absence of immunoreactivity is closely correlated with the histochemical characteristics of the cellular components determined in this species (Crespo et al, ). In fact, the SC that react with these antibodies present a positive reaction with alcian blue pH 2.5 and toluidine blue pH 1, which are stains that indicate the presence of acidic molecules (Espada and Stockert, ).…”

“…It should be noticed that the immunonegative SC were those reactive to periodic acid‐Schiff staining, indicating the presence of neutral components (Crespo et al, ). Since transmission electron (TEM) observations (Medina et al, ) revealed that these cells also possess Ca 2+ deposits, Ca 2+ release would involve merocrine, holocrine, and apocrine processes, instead of the calcium pump.…”

Ultrastructure of the oviductal mucosa of Leptodactylus chaquensis. Analysis of the preovulatory and postovulatory periods

“…As an exception, the cells of the pc present SG with homogeneous acidic and predominantly sulphated contents (Alcaide de Pucci, 1991a). In R. arenarum a wide variety in the secretion profile of proteins, glycoconjugates and ions in each segment of the PC has been demonstrated (Medina et al , 2000; Crespo et al , 2009).…”

“…However, there are few studies that focus on the oviductal morphology of anurans and they are limited to some species and to some periods of the reproductive cycle (Shivers & James, 1970; Yoshizaki & Katagiri, 1981; Yoshizaki, 1985). Only the R. arenarum oviduct has been studied at the histological, ultrastructural and functional level throughout the reproductive cycle (Fernández et al , 1989; Winik et al , 1999; Fernández & Ramos, 2003; Medina et al , 2007; Crespo et al , 2009; Medina et al , 2012). With respect to L. chaquensis , at present the structural organization (Alcaide de Pucci, 1991b) and the histochemical analysis (Alcaide de Pucci, 1991a) of the oviduct during the preovulatory period have been studied by optical microscopy.…”