Influence of ovulation conditions upon the metabolism and cleavage capacity in Bufo arenarum oocytes
✍ Scribed by Bühler, Marta I.; Zelarayán, Liliana
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 70 KB
- Volume
- 278
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Ovarian fully grown oocytes have two different types of metabolic behavior that are closely related to the seasonal variations in Bufo arenarum. During the reproductive period, the increase of gonadotropic activity modified the metabolism of ovaric oocytes by enhancing the activity of the pentose phosphate cycle and the glutamic aspartic cycle. This metabolic behavior, which remained unchanged during ovulation, fertilization, and early development, would represent a metabolic adaptation needed to satisfy the requirements for precursors during cleavage. Moreover, during the winter period, ovarian oocytes broke down carbohydrates through the Embden Meyerhof route followed by a classical Kreb's cycle. When ovulation was induced "in vivo'', the short period required (5-6 h) was not long enough to modify the metabolic behavior of oocytes, which exhibited the same metabolism in the coelomic cavity as that observed in the ovary. Nevertheless, if these oocytes were allowed to continue their transit down through the oviducts and accumulate in the ovisacs, their metabolism changed to that of summer oocytes. The observation that follicle-stimulating hormone (FSH) may induce "in vitro" a change in the metabolic activity of winter oocytes suggests that this hormone would be present in oviducal fluids. In addition, the cleavage capacity was directly related to the type of metabolism operating in the oocytes. In fact, only those oocytes with a metabolism characteristic of the reproductive period are able to cleave after fertilization.