Injection is directly through the firm cephalic plaque into the coelom.
This plaque can be located by the prominent flattened golden setae that are embedded at the base. In vivo exposure to isotopes Oocytes or embryos are labeled in vitro by immersing them directly into membrane filtered seawater containing the isotopes. Pulses can be from 2 to 8 hours. The coverslips are cemented to slides with the cells facing upward. After dipping the slides in Kodak NTB2 or Ilford G-5 emulsions, they are exposed for 2 weeks.