1/2. Ultrastructural study of benign osteoblastoma of the maxilla.The ultrastructure of benign osteoblastoma of the maxilla in a 14-year-old boy was studied. Morphologically, the tumor tissue was composed of abundant osteoid of a trabecular form, and cellular and vascular connective tissue. The cellular components were osteoblasts, osteoclasts, osteocytes entrapped within the osteoid, and small perivascular cells of two types. The small cells of one type were ovoid and had a relatively large nucleus and a dark cytoplasm. The cells of the other type were elliptical and had a clear cytoplasm. The former seemed to be a preosteoblast and the latter could not be identified. The osteoblast was the predominant cell in this lesion and was characterized by the presence of abundant rough-surfaced endoplasmic reticulum and several Golgi complexes. These characteristics indicated the pronounced activity of collagenous fiber synthesis and the matrix of the osteoid tissue.- - - - - - - - - - ranking = 1keywords = nucleus (Clic here for more details about this article) |
2/2. Histological and fine structural studies on pigmented neuroectodermal tumor of infancy.Pigmented neuroectodermal tumor of infancy originating from the anterior maxilla in a two-month-old male has been studied by light and electron microscopy. The tumor is characterized histologically by two types of neoplastic cells embedded in considerable amounts of fibrous stromal tissue. The first type of cell is cuboidal to columnar in shape with an epithelial appearance having abundant cytoplasm; either scanty or a heavy accumulation of melanin pigment is observed in the cytoplasm. These cells are aligned along the cleft-like space or arranged in small ductal structures. Electron microscopy shows the characteristic features of melanocytic cells having a varying degree of asynchronous maturation of melanosomes. The second type of cells is small and round in shape and has a hyperchromatic nucleus and scanty cytoplasm, resembling neuroblastic cells or lymphocytes. Electron microscopy reveals cytoplasmic processes resembling immature neuritis which protrude into the intracellular space; a small number of secretory granules having a central core surrounded by a single limiting membrane are observed in the cytoplasm and cytoplasmic processes.- - - - - - - - - - ranking = 1keywords = nucleus (Clic here for more details about this article) |