Timing of implantation in the northern fur seal, Callorhinus ursinus

Abstract

We describe the timing of three stages of implantation in the northern fur seal, Callorhinus ursinus. The median date of formation of the implantation chamber is 14 November (± 1 SE = 2 days) ca. 237 days prepartum and 123 days postcopulation, of the amnion it is 22 November (±1 SE = 3 days), and of the embryo, it is 29 November (±1 SE = 3 days). The estimated rate of failure of implantation is 11.5% (± 1 SE = 0.1). Implantation dates are earlier in larger and older females.