Sperm capacitation refers to the physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg. This term was first coined in 1952 by Colin Russell Austin based on independent studies conducted by Austin and

The embryological treatise De formatione ovi et pulli (On the Formation of the Egg and of the Chick) was written by anatomist and embryologist

Preformationism was a theory of embryological development used in the late seventeenth through the late eighteenth centuries. This theory held that the generation of offspring occurs as a result of an unfolding and growth of preformed parts. There were two competing models of preformationism: the

Ovism was one of two models of preformationism, a theory of generation prevalent in the late seventeenth through the end of the eighteenth century. Contrary to the competing theory of epigenesis (gradual emergence of form), preformationism held that the unborn offspring existed fully formed in the eggs or

Spermism was one of two models of preformationism, a theory of embryo generation prevalent in the late seventeenth through the end of the eighteenth century. Spermist preformationism was the belief that offspring develop from a tiny fully-formed

Eduard Friedrich Wilhelm Pflüger was a physiologist known for his research on respiration and the respiratory quotient, experiments on the effects of electricity on muscles and nerves, and his study of the ovaries and eggs development. His experiments on how the gravitational orientation of frog eggs affects their cleavage plane inspired embryologists such as

Ovum Humanum was written and compiled by Dr. Landrum Brewer Shettles while he worked as a doctor in New York. The publication contains an atlas of photographs of the