Resumo

NAVARRO-MALDONADO, Ma. del Carmen et al. Desarrollo embrionario temprano en el hamster Sirio Dorado, Mesocricetus auratus (Mammalia: Rodentia). Acta Zool. Mex [online]. 2000, n.81, pp.105-115. ISSN 2448-8445.

The pattern of embryonic segmentation in the golden sirian hamster (Mesocricetus auratus) was analized using two female groups: 47 nuliparous 3-4 months old females and 39 multiparous (mean 3 parturitions) 7-8 months old females. The mating time was restricted to 15 minutes and the time of ovulation was determined on the basis of secuencial studies of vaginal citology. The best moment to obtain 8-blastomeres embryos was between 62 and 63 hours postcoitus for nuliparous females. In multiparous females the time of segmentation was 2 hours longer in comparison to nuliparous. We propose that the increase in pregnancy duration, that has been correlated with age in females, occurs already during the very early embrionic development stages. In order to estimate the time of early segmentation in the golden sirian hamster, it is neccesary to restrict the mating time and to relate it accurately with the occurrence of ovulation, and to establish the age and parturition number in females. Besides, the segmentation process shows a clear asyncrony in multiparous females, making possible to recover embryos that belong to 4 distinct segmentation phases (2, 4, 6 and 8 blastomeres) between 60 to 63 hours postcoitus.

Palavras-chave : Embryonic development; hamster; pregnancy duration; Mesocricetus.