Complex sentence: The hybridomas can be grown indefinitely in a suitable cell culture media, or they can be injected in mice (in the peritoneal cavity, the gut), they produce tumors containing an antibody-rich fluid called ascites fluid.
Split into simpler sentences: The hybridomas can be grown indefinitely in a suitable cell culture medium.They can also be injected into mice (in the peritoneal cavity, surrounding the gut). There, they produce tumors secreting an antibody-rich fluid called ascites fluid.