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.
No. 5: Zeus and Willow. Zeus, the No. 43 most popular male cat name, is a bit of an anomaly. It was in the top 100 in the early 2000s, fell out of favor and then re-entered the list in 2009, gaining popularity ever since. Willow has gone from being the No. 74 most popular female cat name in 2003 to No. 23 in 2012.