DIFFERENTIATION OF SMOOTH-MUSCLE CELLS FROM UNDIFFERENTIATED CELLS OFCHICKEN GIZZARD OCCURS ON THE LAYER OF FIBROBLAST-LIKE CELLS

We examined the in vitro differentiation of smooth muscle cells from u ndifferentiated cells of embryonic chicken gizzard, We used the gizzar d from 7-day-old embryos (Hamburger and Hamilton's stage 26-28) as a s ource of culture, since the expression of myosin is extremely low, and the gizzard consists of round cells, which are not stained by anti-sm ooth muscle myosin antiserum. When the dissections of the gizzard were cultured, they attached to the dish, and fibroblastlike cells migrate d within 4 days after the culture. Then round cells migrated from the transplants over the layer of fibroblast-like cells. At 12-14 days aft er the culture, smooth muscle cells, which were ribbon-shaped and stai ned by anti-smooth muscle myosin antiserum, appeared in the layer of r ound cells. The dissected transplant itself was not stained by anti-sm ooth muscle myosin antiserum even after being cultured for 15 days, We concluded then that the smooth muscle cells were differentiated from the round cells, which spread on the layer of the fibroblast-like cell s, We also observed the differentiation of smooth muscle cells when th e cells separated from 7-day-old embryo cultured on the layer of clone d fibroblast cells. We suggest that the fibroblastlike cell may play a n important role in the differentiation of smooth muscle cells.