The purpose of the peritoneum in a pig fetus is to line the abdominal wall cavity and to help protect the inside of the abdominal cavity. A peritoneum is a thin layer of membrane that is located under the muscle layers of the abdomen.
The peritoneum is also important in a fetal pig because it is able to cover the organs that are located in the peritoneal cavity. The organs that are located in this cavity are surrounded by a thick membrane of liquid that acts as a lubricant and allows the organs to move around a small amount within the cavity.
The easiest way to see the function of the peritoneum in a fetal pig is to perform a dissection. The dissection will not only give insight into where the organs and various systems lie in the pig's body, but will also give an idea of how the organs work together to function. A fetal pig will have all of the organs that an older pig will have, but they will be more defined and easier to see and understand. Fetal pigs will also have the addition of an umbilical cord which can give insight into how the pig survives while still in the womb.