Ovum humanum, while in essence an atlas of photographs of egg cells, also includes brief textual descriptions of Shettles’ experience compiling his photos and the methods he used. Shettles describes the many late nights he spent in the dark room of Columbia Presbyterian Hospital over a period of six years photographing eggs, obtained from his various patients at Columbia Presbyterian, at different stages of development both prior to as well as after fertilization. Shettles also describes the tools he used to capture these photographs, which included a Zeiss phase contrast microscope to which he attached a Leica camera. This setup provided unparalleled viewing and photographic documentation of the egg cells that Shettles compiled for his book. Shettles reports that during the six years he took photographs of over one thousand human egg cells in order to create a comprehensive compilation of these photographs. Once published, many of the book’s readers viewed the photographs as equally significant as both scientific reference material and artwork. Many of the photos contain shapes and images that would later be compared to photographs of outer space as well as more familiar images like animals and faces.