LS-2-P-6059 STRUCTURE OF NUCLEOLI IN OOCYTES FROM BIDDER´S ORGAN OF CUBAN ENDEMIC TOADS (ANURA: BUFONIDAE, PELTOPHRYNE)

The nucleolus is the nuclear subdomain that assembles ribosomal subunits in eukaryotic cells and it is the largest structure in the cell nucleus. The nucleolar organizer regions of chromosomes, which contain the genes for pre‐ribosomal ribonucleic acid, serves as the foundation for nucleolar structure. The nucleolus disassembles at the beginning of mitosis, its components disperse in various parts of the cell and reassembly occurs during telophase and early G1 phase. In amphibian´s oocytes there are a lot of nucleoli during previtellogenic stages which synthesize part of the necessary machinery that brings the maternal cytoplasm to start protein synthesis in the early embryo. On the other hand, Bidder´s organ (OB) is a vestigial organ in any member of the Bufonidae family located in cranial tip of the male and maybe female gonad. Normally it is inactive and contains little previtellogenic follicles or previtellogenic oocytes. The main goal of this work is to show the presence and structure of nucleoli in nuclei from oocytes of Bidder´s organ in Cuban toads as well as trying to explain why their presence and development in apparently vestigial and possibly nonfunctional structures.
Three male’s toads of Peltophryne fustiger, P. peltocephala, P. florentinoi, P longinasus, P. gundalchi, P. taladai and P. cataulaciceps were collected in their habitats through Cuban archipelago and ethically euthanized. Gonad fragments were fixed in Bouin's fluid, Paraformaldehyde and Glutaraldehyde to be processed for light microscopy and TEM respectively.
The results show that the gonad of the male from all studied species has one pair of Bidder’s organs just above the testes on each cranialis part. Previtellogenic oocytes were seen and as in other members of the Bufonidae Family it was found that ovarian and Bidderian oocytes were morphologically identical. Two or three nucleoli were observed in each nucleus whose structure resemble normal morphology, with ribosomes presents.
Although the presence of previtellogenic follicles is referred to OB as a rudimentary ovary, the structure and dimensions of the nucleoli in those nuclei of Cuban toads indicates that they are active cells capable of producing ribosomes, to ensure protein synthesis. No vitellogenic follicles that may suggest a real function of body Bidder as a producer of viable female cells were observed, however we do not know the reason for the maintenance of the BO. So, it´s possible to suggest the possibility that Bidder´s organ may be an active endocrine organ rather than a simple, rudimentary ovary.