Important role of collective cell migration and nerve fiber density in the development of deep nodular endometriosis.

OBJECTIVE To evaluate deep nodular endometriotic lesions induced in baboons over 12 months and analyze collective cell migration and nerve fiber density. DESIGN Morphologic and immunohistochemical analysis of endometriotic lesions induced in baboons over the course of 1 year. SETTING Academic research unit. ANIMAL(S) Three female baboons (Papio anubis). INTERVENTION(S) Recovery of induced deep nodular endometriotic nodules from baboons. MAIN OUTCOME MEASURE(S) Evaluation of the morphology of glands by analysis of the center of lesions and the invasion front; immunohistochemical staining with Ki67, E-cadherin, and β-catenin for investigation of mitotic activity and cell-cell junctions, and with protein gene product 9.5 and nerve growth factor (NGF) for study of nerve fiber density (NFD). RESULT(S) All (100%) of the lesions were invasive 1 year after induction, compared with 42.29% after 6 months. Glands from the invasion front showed significantly reduced thickness but significantly higher mitotic activity. E-Cadherin and β-catenin expression were similar between the center and front. NFD was significantly higher in lesions induced after 1 year than after 6 months, and NGF expression was significantly lower in 1-year lesions than in 6-month lesions. CONCLUSION(S) Nodular endometriotic lesions induced in the baboon model were found to be significantly more invasive and innervated after 12 months than after 6 months. The invasive phenotype was highly expressed in glands at the invasion front, and our study suggests that nerve fibers play a role in the development of lesions as observed in women.