Biología de la Reproducción Amphibian oogenesis

MÓNACO ME; VILLECCO EI; SÁNCHEZ SS

Tafí del Valle, Tucumán

Congreso; XXI Annual Scientific Meeting of Tucumán Society Biology; 2004

Asociación de Biología de Tucumán

Oogenesis is a complex process that leads to the formation and differentiation of the female gamete. Within the gonad, the development of each gamete is mainly mediated through the follicles which undergo progressive cellular and molecular interactions. One of the most relevant events in amphibian oogenesis is the marked gene expression and accumulation of transcripts during primary oocyte growth. The high pattern of accumulation of different RNAs is related to the requirement for stored components to be used in early development. In the Ceratophrys cranwelli species, the oocyte contains high levels of RNAs as a consequence of a gene amplification that produces multiple nucleoli and of the RNAs from the follicle cells present in the cortical vesicles. At present, the data on the possible functions of maternal localized RNAs is limited. We study the maternal connexin mRNA expression pattern, probably related with the vitellogenesis and maturation process. Besides RNAs, oocytes store components to meet all nutritional requirements of the embryo until it is able to consume food. Thus, a large number of yolk platelets accumulate during the vitellogenic phase. When the oocytes complete their growth in the ovary (full grown oocytes) they are arrested at the prophase of meiosis I. However, they are not able to be fertilized or support embryonic development unless they undergo oocyte maturation. This process corresponds to a complex differentiation program that transforms the oocyte into an egg that is fertilization competent. We have demonstrated a possible connection between the intra-oocyte cAMP level and the coupling/uncoupling of gap junctions. cAMP was proposed as a regulatory molecule in the meiotic arrest of Bufo oocytes. Analysis of the oocyte-follicle cell interface during the amphibian oogenesis revealed the development of a complex cell-cell interaction that changes throughout the various oogenetic periods.