Having come from an egg, one should never belittle them;
from tiny eggs mighty mammals grow.
The typical adult human body is made of trillions of cells.
Each of these arises by cellular division from a single cell. The
embryo of any animal that produces sexually grows by cellular
division or mitosis from a single fertilized cell called a zygote
(pronounced with two syllables), which is the union of two gamete
cells (a sperm cell from the male and an ovum from the female).
In 1744 Albrecht von Haller coined the term evolution to
describe the then prevailing theory (also known as preformation)
that every human was preformed by God at once, each person nested
inside the sperm of his or her father, which was nested inside the
sperm of his father, and so forth back to Adam.
I am amazed that it wasn't until Von Baer's work in 1826
that anyone proved that mammals grew from eggs, maybe because of
the inherent difficulty of observing the process in the
laboratory, or because humans believed that mammals like us were
not like other animals. Ever one's own biases blind one to the
Von Baer went on to study the embryonal development of
animals, and discovered the blastula stage and the notochord.
The biologist Gregor Mendel, who published the laws of genetic
inheritance in 1865, coined the term gamete.
See also in The book of science: