(A) Phase contrast image of mouse hepatic stellate cells cultured for 2 days. These hepatic stellate cells are still quiescent, as evidenced by their vitamin A lipid deposition, a stellate morphology, and presence of dendritic processes. (B) Phase contrast image of mouse hepatic stellate cells cultured for 14 days. By this time, hepatic stellate cells are fully activated and exhibit dramatic changes in their morphology and reduction in lipid deposition. (C) Fluorescence image of hepatic stellate cells in healthy adult mouse liver stained for desmin. (D) Fluorescence image shows α-SMA immunostaining in CCl₄-induced fibrosis in the adult mouse liver. (E) Confocal single-plane image of Tg(hand2:EGFP) expression in zebrafish hepatic stellate cells at 5 days after fertilization. The hepatic stellate cells exhibit a stellate morphology and send out complex protrusions (23). (F) Confocal single-plane image of hepatic stellate cells labeled by Tg(hand2:EGFP) expression in zebrafish larvae treated with 2% ethanol from 4 to 5 days after fertilization. Hepatic stellate cells become activated upon the acute ethanol assault, as evidenced by the loss of complex cellular processes and elongated cell body, suggestive of changes in contractility (24).