This fertilized ovum, known as a zygote, is a large diploid cell that is the beginning, or primordium, of a human being. — Keith L. Moore Copy Share Image
“Once an egg has been fertilized and managed to attach itself to the wall of the uterus and gastrulates (produces the three layers), the next key stage is the development of the “blastocyst,” the sack or sphere of just one… — Bill Nye Copy Share Image
