Histoloxía en estudos de reproducción en cefalópodos
“Contrasting macroscopic maturity staging with histological characteristics of the gonads in female Octopus vulgaris” e o título do último artículo (publicado en Hydrobiologia) no que colaboramos. Ainda que non participamos como coautores, o Grupo de Ecoloxía Pesqueira (CSIC) puso a disposición dos autores o seu servizo de análise de imaxe, ademais de prestar apoio e asesoramento no uso do método estereolóxico e contribucións útiles durante a preparación do manuscrito.
A histoloxía e as técnicas estereolóxicas son usados de forma habitual en estudos reproductivos de peixes; pero son pocos os casos onde esta metodoloxía aplicase a cefalópodos. Como parte dun amplio estudo do proceso madurativo do Octopus vulgaris, Sieiro et al. usaron os principios da estereoloxía para desnrolar un novo índice histolóxico de madurez.
RESUMO: We contrasted histological characteristics with a macroscopic maturity scale in Octopus vulgaris. Seven histological stages of maturation were identified, and a stereological method was used to develop a new histological maturity index (HMI). This index was related to the gonadosomatic index giving the possibility to estimate the histological stage of individual octopus without sampling the gonads. However, the existing macroscopic maturity scale produced some degree of overlap along the range of HMI, suggesting that this macroscale at this moment might be just good enough to separate immature from fully mature individuals. A histological maturity criterion based on the presence of a larger proportion of folding oocytes compared to earlier microstages resulted in a size at maturity of 1.5 kg. However, using two different macroscopic criteria, size at maturity was 1.3 and 2.3 kg. The estimate of size at maturity is therefore sensitive to the maturity criteria used. The maturation cycle of female O. vulgaris was seasonal, peaking in spring months and reaching a maximum of reproductive activity in April independently of the maturation criteria used. Oogenesis was reviewed and found to be an asynchronic process. Our results suggest that there is a need to examine all these issues in other cephalopod species.