Injection volume influences tumor architecture and desmoplastic response. Injection volume influences tumor architecture and desmoplastic response. (A) Representative H&E-stained slides of 14-day-old tumors derived from orthotopic injection of 104 Hy15549 cells suspended in 50 µl, 30 µl or 10 µl Matrigel. Increasing Matrigel volume correlates with the size of the cystic center (dashed lines). The effect was abrogated at 10 µl injection volume. (B) Representative Sirius Red- and H&E-stained slides of 14-day-old tumors after 30 µl injection of cells. There is decreased desmoplasia near the cystic center of the tumor. (C) Residual Matrigel is associated with abnormal tumor architecture, including an innermost organized border, followed by glandular differentiation of cells and dense stroma near the periphery. Derek J. Erstad et al. Dis. Model. Mech. 2018;11:dmm034793 © 2018. Published by The Company of Biologists Ltd