Images Dated 7th December 2005

Uterus lining during menstruation, SEM

Uterus during menstruation. Coloured scanning electron micrograph (SEM) of the lining of the uterus being shed during menstruation. The upper layers (red) are being shed and the breakdown of the underlying blood vessels releases red blood cells (red dots). Menstruation occurs for a few days during a woman's menstrual cycle. Prior to menstruation, the uterine lining (endometrium) thickens to prepare it for the reception of a fertilised egg. If a fertilised egg enters the uterus, it implants in the wall and develops into an embryo. If the released egg is not fertilised, the thickened wall is shed

© STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

Corpus luteum, SEM

Corpus luteum. Coloured scanning electron micrograph (SEM) of a corpus luteum, or yellow body (brown), in an ovary. The corpus luteum is formed after ovulation, from the ovarian follicle that released the egg. The function of the corpus luteum is to secrete the hormone progesterone to ready the uterus for the implantation of a fertilised egg. If the egg is not fertilised it stops secreting and degrades after roughly 12 days

© STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

Collapsed ovarian follicle, SEM

Collapsed ovarian follicle. Coloured scanning electron micrograph (SEM) of an ovarian follicle just after ovulation (release of an egg). The central lumen is filled with red blood cells (yellow) from a collapsed blood vessel. Surrounding the lumen are cuboidal follicular cells (blue). The follicle will form into the corpus luteum, or yellow body. The function of the corpus luteum is to secrete the hormone progesterone to ready the uterus for the implantation of a fertilised egg. If the egg is not fertilised it stops secreting and degrades after roughly 12 days

© STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY