At 56-57 postovulatory days old, an embryo measures 23-32 mm in length, that is, up to about an inch long. Distinguishing characteristics of this stage include fusion of the eyelids at the margins, clear distinction of the subdivisions of the upper and lower limbs, the forearms appear at or above the level of the shoulders and the external genitalia are well developed but not always sufficiently to distinguish the embryo's sex.