Born 21 Apr 1849; died 25 Oct 1922 at age 73.

Oskar (Wilhelm August) Hertwig was a #German #embryologist and #cytologist who did extensive work on the #nuclear #transmission of #heredity.

He was the first to recognize that the essential event in #fertilization is the #fusion of the #nuclei of the #sperm and #ovum.

In 1875, he observed all the steps in fertilization, including the union of egg and sperm #chromosomes in sea urchins. These animals are particularly suitable for microscopic studies because of their transparency. He saw there was a single nucleus before fertilization and two nuclei immediately afterwards. He realized the second nucleus had come from the #spermatazoon, and thus a single spermatazoon can #fertilize an #egg.

He also investigated #malformations of #vertebrate #embryos.

www.masterdoctorclinic.com