Deoxycorticosterone‐induced precocious hatching of teleost embryos

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Abstract
Embryos of the teleost (Oryzias latipes) incubated at 22–23°C in medium containing deoxycorticosterone (DOC) at a concentration of 1μg/ml hatched in 11.7 days; embryos incubated under identical conditions in rearing medium alone or in rearing medium plus the steroid vehicle hatched in 22.3 and 22.2 days, respectively. The rate of development of embryos incubated with DOC was not different from that of control. Addition of DOC to the rearing medium at either 0, 4, or 8 days after fertilization resulted in a reduction of hatching time relative to the control group, but there was no significant difference in the time of hatching between these DOC‐treated groups. Increasing the rate of embryogenesis by increasing incubation temperature to 28°C resulted in a decrease in hatching time in both DOC‐treated and control embryos. The time required for hatching decreased in a dose‐dependent manner as the concentration of DOC in the incubation media increased from 0 to 1 μg/ml. Since hatching of teleost embryos is dependent upon enzymatic solubilization of the chorion, these data suggest that exogenous deoxycorticosteron induces the precocious release of hatching enzymes from the teleostean larvae.