A Study on Relationship between Sperm Penetration and Egg Activation in the Medaka, Oryzias latipes

A physiological study has been made of the initial phase of fertilization in the medaka, Oryzias latipes. It was found that the effective attachment of a spermatozoon to the ovoplasm was established within 5 seconds after insemination. However, average reaction time for the breakdown of cortical alveoli evoked by stimulation of the spermatozoon or by pricking of the egg was 47±8 seconds and 20±3 seconds, respectively. Single stimulation by pricking is sufficient to evoke the excitation of ovoplasm. It was calculated, therefore, that the stimulus by the spermatozoon evoked the excitation of ovoplasm about 27 seconds after insemination. From these results, it was concluded that the effective attachment of a spermatozoon to the ovoplasm was attained prior to the activation of ovoplasm.Article信州大学理学部紀要 2(1): 87-94(1967)departmental bulletin pape

Distribution and chromosomal diversity of Thai-medaka, Oryzias minutillus in Thailand

Article信州大学理学部附属諏訪臨湖実験所報告 9: 137-147(1995)departmental bulletin pape