American Journal of Primatology 69:36–45 (2007) RESEARCH ARTICLE Histomorphology of the Mandibular Condylar Cartilage in Greater Galagos (Otolemur spp.) ANNE M. BURROWS 1,2Ã AND TIMOTHY D. SMITH 2,3 1 Department of Physical Therapy, Duquesne University, Pittsburgh, Pennsylvania 2 Department of Anthropology, University of Pittsburgh, Pittsburgh, Pennsylvania 3 School of Physical Therapy, Slippery Rock University, Slippery Rock, Pennsylvania The functional morphology of the primate craniomandibular complex and temporomandibular joint (TMJ) components is frequently discussed in terms of gross skeletal structure. At the histomorphologic level, however, the TMJ has only been studied in Old World anthropoids. The present study is designed to describe the microanatomy of the condylar cartilage of the TMJ in two closely related species of greater galago: the exudativorous Otolemur crassicaudatus and the frugivorous O. garnettii. TMJs with intact joint capsules were harvested from adult, cadaveric specimens of these species (four O. crassicaudatus and five O. garnettii). The samples were decalcified, processed for paraffin sectioning, and sectioned at 10–18 mm in the coronal plane. The samples were then stained with hematoxylin/eosin, Gomori trichrome, and Alcian blue, and examined with a photomicroscope. Generally, condylar cartilage in O. crassicaudatus was thickest both laterally and centrally, while O. garnettii had the relatively thickest cartilage laterally. Both species displayed a superficial articular zone, a middle proliferative zone, and a deeply located hypertrophic zone in the condylar cartilage. O. crassicaudatus typically had the greatest cell density in each of these zones. In addition, O. crassicaudatus had focal concentrations of Alcian blue laterally and centrally, while O. garnettii had the greatest reactivity in the central portion only. These results suggest that O. crassicaudatus may be specialized to resist greater compressive force at the TMJ condylar cartilage in specific regions of the mandibular condyle. Am. J. Primatol. 69:36–45, 2007.  c 2006 Wiley-Liss, Inc. Key words: temporomandibular joint; histology; exudate; galago; condylar cartilage Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ajp.20325 Received 5 July 2005; revised 24 January 2006; revision accepted 24 January 2006 Ã Correspondence to: Anne M. Burrows, Dept. of Physical Therapy, 600 Forbes Ave., Duquesne University, Pittsburgh, PA 15282. E-mail: burrows@duq.edu r r 2006 Wiley-Liss, Inc.