Experimental oral foreign body reactions: vegetable materials

Foreign bodies and tissue reactions to foreign materials are commonly encountered in the oral cavity. Exogenous materials most commonly causing foreign body reactions are metallic in origin (usually amalgam). Of the nonmetallic materials seen during biopsies, suture materials and vegetable matter are most often observed. Since many foodstuff foreign materials are unidentifiable histologically, common vegetables were experimentally implanted subcutaneously in rats to assess local host responses and to characterize the nature of these materials microscopically. The histologic characteristics of these vegetable foreign body reactions are detailed herein. The implanted materials correspond to reactions seen in human subjects.

Ultrastructural evidence for luteinizing hormone-releasing hormone neuronal control of estrogen responsive neurons in the preoptic area

Both estrogen receptor (ER) immunoreactive (ir) and LHRH-ir neurons and processes are present in the preoptic area of the guinea pig. This experiment was conducted to determine if LHRH-ir terminals interact synaptically with ER-ir cells. A light microscopic dual chromogen immunocytochemical technique employing diaminobenzidine (DAB) and nickel-enhanced DAB for LHRH and ER localization, respectively, revealed that many varicose LHRH-ir fibers coursed in close proximity to ER-ir cells in the anterior part of the preoptic area at the preventricular periventricular nucleus (Pep), suggesting the likelihood of synaptic interactions. Ultrastructural analysis was performed using DAB and 3,3',5,5'-tetramethylbenzidine (TMB) for LHRH and ER localization, respectively. DAB labeling in LHRH-ir neurons appeared as a dense flocculent product dispersed throughout the cytoplasm. TMB stained ER-ir neurons contained electron dense crystalline spicules located predominantly in their nuclei. Numerous TMB labeled ER-ir neurons were present in the Pep, and occasionally occurred in clusters, closely apposed to one another. Many LHRH-ir terminals made synaptic contact or were apposed to unlabeled dendrites, while fewer contacted perikarya. Most significantly, ER-ir neurons showing clear evidence of intranuclear TMB crystals received synaptic input from LHRH-ir terminals. In addition, LHRH-ir terminals lacking synaptic specializations were also in direct apposition to ER-ir perikarya. These results provide morphological evidence that LHRH-ir neurons can regulate ER-ir neurons in the preoptic area. Since LHRH-ir cells are thought to be regulated by estrogen responsive neurons, interaction of LHRH terminals with ER-ir cells may represent a regulatory feedback circuit between the two systems.

Experimental oral foreign body reactions. Commonly employed dental materials

Foreign bodies and tissue reactions to foreign materials are commonly encountered in the oral cavity. The more common lesions include apical deposition of endodontic materials, mucosal amalgam and graphite tattoos, myospherulosis, oil granulomas, and traumatically introduced dental materials and instruments. Since many foreign materials are unidentifiable histologically, commonly used dental materials were experimentally implanted subcutaneously in rats to assess local host responses and characterize the nature of these materials microscopically. The histologic characteristics of these foreign body reactions are detailed herein. The implanted materials corresponded to reactions seen in human subjects.

Ontogeny of a sexually dimorphic opioid system in the preoptic area of the rat

A striking sexual dimorphism exists in the distribution of Met-enkephalin (m-ENK) immunoreactive fibers in the preoptic area of the rat brain. A dense plexus of m-ENK fibers, approximately 100 microns wide, is present in the periventricular part of the preoptic area (pePOA) in adult females, but not in males. In the present study, we have examined the time of first expression of this female-typical system during the course of normal brain development. The female-typical plexus of m-ENK fibers in the pePOA is not expressed prepubertally, but first becomes evident during the late peri-pubertal period (usually by 40 days of age). In adult females, the maintenance of immunohistochemically detectable levels of m-ENK in this fiber system is dependent upon the presence of gonadal steroids, especially estradiol. Therefore, we examined whether exposure of pre-pubertal females to estradiol would result in precocious expression of the m-ENK fiber plexus. The results of this experiment demonstrate that exposure to estradiol for 7 days induces the full expression of the m-ENK fiber system in the pePOA of prepubertal females, such that it was indistinguishable from that seen in mature animals. These results demonstrate that while the sexually dimorphic m-ENK system of the pePOA is not normally expressed prepubertally, the neural substrate is nevertheless in place and capable of being activated by exposure to exogenous estradiol.

Oral granular cell tumors: a clinicopathologic and immunocytochemical study

To investigate the histogenesis of the granular cell, a large series of granular cell tumors was studied for clinical and histopathologic features with emphasis on immunocytochemical markers. The nongingival granular cell tumors (NGGCT) were found to be more prevalent among females than males by a ratio of 2:1 and arose on the tongue (67%), the buccal mucosa (13%), the lips (8%), the soft palate (6%), and other sites (6%). With the use of the avidin-biotin-peroxidase method, polyclonal rabbit antisera were employed. The antisera were directed to the following antigens: S-100 protein, myoglobin, myosin, actin, desmin, alpha-1-antitrypsin, and muramidase. Results indicated that granular cell tumors are not homogenous for immunocytochemical markers. Nongingival granular cell tumors were universally positive for S-100 protein and failed to exhibit immunoreactivity for myogenous or histiocytic markers. Alternatively, the gingival granular cell tumor of infancy was negative for all markers, whereas rhabdomyoma was reactive with myogenous markers and a subpopulation of tumor cells displayed S-100 protein immunoreactivity. The granular cell ameloblastoma was reactive only with antiserum to alpha-1-antitrypsin. Ultrastructurally, granular cells from one of two NGGCT showed a direct evolution from skeletal muscle fibers. It is concluded that the oral NGGCT is a tumor positive for S-100 protein that may arise from muscle or nerve sheath.