The organ culture and grafting of lamprey cartilage and teeth.

Cartilage from larval (ammocoetes) and adult (prespawning upstream migrant) lamprey was successfully maintained both when cultured in vitro or grafted in vivo (on the chorioallantoic membrane (CAM) of host chick embryos). In addition teeth from adult lamprey were successfully cultured in vitro. Cartilages were cultured in supplemented Lebovitz's l15 medium at 15 and 20 degrees C for periods of up to 56 d and in supplemented BGJb medium at 37 degrees C for periods of up to 14 d. Cartilages were also grafted onto the CAM for up to 16 d. Both the cultured and grafted cartilages retained their structural and cellular integrity as verified histologically. The viability of the cartilage, even after extended culture periods, was demonstrated ultrastructurally by the presence of chondrocytes displaying abundant rough endoplasmic reticulum, mitochondria, and Golgi apparatii with associated vesicles. In addition the cartilages were shown to be metabolically active in vitro by the incorporation of radioactive sulfur into the matrix. Some cell outgrowth from other tissues, such as connective tissue, muscle, and gill when left adjacent to the cartilage, occurred over time in cultures. No cell outgrowth was observed in CAM-grafted tissue nor was there any invasion of the agnathan tissue by chorioallantoic blood vessels. Teeth cultured in L15-supplemented media for up to 14 d at either 15 or 20 degrees C retained their structural and cellular integrity as observed histologically, with no apparent cell outgrowth. With the successful culture of these tissues, their development, biochemistry, and physiology, potentially of great importance in understanding early vertebrate evolution, can be better understood.