Medially, however, the peritoneum reflects on the roof of the bladder and runs sharply dorsally, away from the deep layer of transversalis fascia.
It curves downward and medialward in front of the Iliacus and Psoas, and, as a rule, is covered by peritoneum on its sides and anterior surface only.
In 1942, Merrill Chase discovered that cells taken from the peritoneum of Guinea pigs that had been immunized against an antigen could transfer immunity when injected into Guinea pigs that had never been exposed to the antigen; this phenomenon was the discovery of cell-mediated immunity.