at the age of 65. His sudden demise deprives the world of a great scientist and even greater person.
Sandy's rise to prominence in osteoclast biology began in his graduate student years at John Hopkins University School of Medicine where his studies with D.G. Walker on osteopetrotic rodents showed that osteoclast progenitor cells were mononuclear cells present in bone marrow and other hemopoietic tissues (e.g., see Marks, 1976;Marks and Walker, 1976). These pioneering studies were remarkable not only for their delineating the origin of osteoclasts but for their prescience about the role of lymphoid cells in osteoclastogenesis.
Although the above studies alone would have secured his role as a leading authority in osteoclastogenesis, Sandy next applied his bone biology expertise to understanding tooth eruption. In a remarkable series of articles with Don Cahill, they demonstrated that tooth eruption required the presence of the dental follicle that surrounds each unerupted tooth (Cahill and Marks, 1980;Marks and Cahill, 1984). The follicle is important because it is the site of the recruitment of mononuclear cells, which then form osteoclasts that resorb alveolar bone to form an eruption pathway (Marks et al., 1983;Wise et al., 1985). Returning to osteopetrotic rodents, Sandy and collaborators showed that in the toothless rat (tl) injections of colony-stimulating factor-1 (CSF-1) early postnatally stimulated eruption by restoring mononuclear cells and osteoclasts (Iizuka et al., 1992). My laboratory then showed that CSF-1 was indeed produced by the dental follicle (Wise et al., 1995). That the mutation in the tl rat was in the CSF-1 gene was demonstrated by Sandy's group just prior to his death (Van Wesenbeeck et al., 2002).
The above studies are only a fraction of the more than 270 publications (including textbooks) written by Sandy. He was the principal investigator on 16 research grants, including being the recipient of a merit award from the NIH. He was a founding member and former president of the American Association of Clinical Anatomists, American editor of the journal of Clinical Anatomy for 10 years, and a member of numerous editorial boards. His scholarship was not confined to science, however, because he was an outstanding teacher of gross anatomy to medical students, both in presentation and in understanding what aspiring physicians should know.
Sandy's outstanding contributions to science and scholarship pale, however, in comparison to the man himself. In these times of turmoil, perhaps we can even better appreciate this man who was internationally respected for his humanitarianism (providing periodontal work at a free dental clinic; organizing a trip to Nicaragua to build a medical clinic); for his recognition that science is global (visiting professor at the Karolinska Institute in Sweden and at the University of Malaysia); and for his hosting and mentoring scientists from a multitude of countries. His innate decency was reflected in his generosity, a generosity not only of giving material things, but also of giving his time, spirit, and counsel. This trait, coupled with his hearty appetite for life and his sense of humor, made him a magnet. Whenever I would see him at a scientific meeting, we would begin to talk. Within two minutes, however, there would be a crowd of people around him. They crowded in, not because they were rude, but because they wanted to be a part of his life, a life that affirmed the worth of each of our lives.