Embryo implantation in humans. After fertilization the human embryo begins a 4 day long journey down the fallopian tube and into the uterus. When the embryo reaches the blastocyst stage it develops two distinct populations of cells. The outer cell mass,called the trophectoderm, and the inner cell mass.
Cat eye glasses. Named after their resemblance to the shape of a cat's eye, cat eye glasses are probably the most popular style of vintage eyeglasses. Though cat eye glasses were around since the 1950's, they reached their peak popularity when Audrey Hepburn wore a pair in the 1961 film Breakfast at Tiffany's.
Eye Color Guide - The Most Common Eye Colors. 1  The human eye is both beautiful and unique. 2  Brown eyes are the most common eye color in the world with over 55% of the world's population having brown eyes. 3  Hazel eyes are similar to brown eyes, although they are typically lighter in color, and have more of a green-yellow tint.