Faculty Bibliography

BACKGROUND:The turtle plastron is composed of a keratinized epidermis overlying nine dermal bones. Its developmental origin has been controversial; recent evidence suggests that the plastral bones derive from trunk neural crest cells (NCCs). RESULTS:This study extends the observations that there is a turtle-specific, second wave of trunk NCC delamination and migration, after the original NCCs have reached their destination and differentiated. This second wave was confirmed by immunohistochemistry in whole-mounts and serial sections, by injecting DiI (1,1', di-octadecyl-3,3,3',3',-tetramethylindo-carbocyanine perchlorate) into the lumen of the neural tube and tracing labeled cells into the plastron, and by isolating neural tubes from older turtle embryos and observing delaminating NCCs. This later migration gives rise to a plastral ectomesenchyme that expresses NCC markers and can be induced to initiate bone formation. CONCLUSIONS:The NCCs of this second migration have properties similar to those of the earlier NCCs, but also express markers characteristic of cranial NCCs. The majority of the cells of the plastron mesenchyme express neural crest markers, and have osteogenic differentiation capabilities that are similar or identical to craniofacial ectomesenchyme. Our evidence supports the contention that turtle plastron bones are derived from a late emigrating population of cells derived from the trunk neural crest.

This article outlines how to perform a standard comprehensive extraoral and intraoral examination and the existing commercially available adjunctive techniques for the early detection of oral cancer and premalignant lesions. Visualization-based techniques (e.g., autofluorescence and chemiluminescence), toluidine blue vital staining, cytopathologic tests and high-risk human papillomavirus testing are discussed in detail, including the indications and protocols for use, their advantages and disadvantages and clinical cases.

Many lesions in the oral cavity may present with a papillary or pebbly clinical appearance. Although the great majority of these papillary lesions are histologically diagnosed as squamous or viral papillomas, there are occasional cases of other more unusual possibilities. Angiokeratomas are uncommon vascular lesions that often present clinically as papillomas. They may also present with other varying clinical appearances that range from pigmented lesions to hemangiomas. However, all forms demonstrate a characteristic microscopic appearance consisting of hyperkeratotic, hyperplastic epithelium covering connective tissue with abundant blood vessels that are sharply confined to the connective tissue papillae. Angiokeratomas generally involve the skin and are often associated with an underlying systemic metabolic disease such as Fabry's disease or fucosidosis. Patients with these systemic diseases may have multiple lesions, with possible involvement of the oral mucosa. However, solitary lesions involving only the oral cavity are rare; only eight previous cases have been documented. In this paper, we describe a case of solitary angiokeratoma presenting as a papillary lesion on the ventral tongue of an 18-year-old male. The lesion was surgically excised and no recurrence has been reported to date. Although this patient had no other lesions or systemic issues, we stress the importance of evaluating a patient with a diagnosis of angiokeratoma of the oral cavity for underlying systemic metabolic disease.