Masayo Hosoi

Morphogenesis of craniopharyngeal derivatives in the neurohypophysis of fisher 344 rats : Abnormally developed epithelial tissues including parotid glands derived from the stomatodeum

Morphogenesis of craniopharyngeal derivatives of the neurohypophysis found in 14 Fischer 344 (F344) rats was studied. The incidence of the craniopharyngeal derivatives was 0.17% in male (7 out of 4,200) and 0.16% in female (7 out of 4,450) F344 rats. Neither a sex-related difference in their incidence nor a strain-related difference in their morphological features was observed. Craniopharyngeal derivatives were composed of aberrant epithelial structures consisting of serous acinar and tubular and fusiform cell structures, and most of these derivatives were associated with Rathkes cleft cysts, which are suggestive of a congenital background. The acinar structures were positive for periodic acid-Schiff reaction and negative for Alcian blue stain. Immunohistochemically, cells forming these structures were positive for cytokeratin, and basal cells of the acinar or tubular structures and some of the fusiform cells showed positive staining for alpha-smooth muscle actin. Electron microscopically, these spindle-shaped basal cells had intracytoplasmic myofilaments with focal density in their cytoplasm, and they were regarded to be myoepithelial cells. These findings strongly indicate that the craniopharyngeal derivatives are not a neoplastic lesion but rather are a developmental aberration derived from the stomatodeum, which is known to be the origin of both nasal and oral epithelial tissues, including the parotid glands, other than Rathkes pouch.

Spontaneous Ganglioneuroma Possibly Originating from the Trigeminal Ganglion in a B6C3F1 Mouse

In a carcinogenicity study, a neuronal tumor in the cranial cavity was observed in a 110-week-old female B6C3F1 mouse. At necropsy, the tumor was seen at the site of the pituitary gland. Histologically, the tumor consisted of well-differentiated ganglion cells, nerve fiber/neuropil-like elements and ganglion-like cells. The tumor was composed mainly of ganglion-like cells, which were arranged in solid sheets interspersed with thin fibrovascular stroma. Nissl substance was detected at the margin in the cytoplasm of well-differentiated ganglion cells, and nerve fibers were identified by the Kluever-Barrera method. Immunohistochemically, the well-differentiated ganglion cells were positive for S-100, neurofilament protein (NF), neuron-specific enolase (NSE), synaptophysin, and chromogranin A. The nerve fiber/neuropil-like elements were positive for S-100, NF, NSE, and glial fibrillary acidic protein (GFAP), and the ganglion-like cells were strongly positive only for NSE and synaptophysin. On the other hand, there were no pituitary cells, such as prolactin-positive or adrenocorticotropic hormone (ACTH)-positive cells in the tumor tissue. Detailed histopathological examination suggested that the tumor might be a ganglioneuroma arising from the trigeminal ganglion. This report provides additional histopathological evidence of peripheral nerve neoplasms in mice.

Adenocarcinoma in the rectum of a capped langur (Presbytis pileata)

A rectal adenocarcinoma in a 22‐year‐old capped langur histologically resembling those in human cases is reported. An ill‐defined diffuse tumor with fibrously firm rectal wall showed diffuse infiltrative growth of signet‐ring cancer cells. Immunohistochemistry demonstrated positive staining for CEA, lysozyme, EMA, keratin and B72.3.

Study on the pathogenesis of foreign body granulomatous inflammation in the livers of sprague-dawley rats.

Focal granulomatous inflammation developed in the livers of five 10-week-old male Sprague-Dawley rats. The characteristic features of this lesion were the presence of foreign body multinucleated giant cells engulfing calcium deposits and site-specific development in a fissure formed in a sub-lobation in the left lobe or interlobar fissure of the medial lobe of the liver. To clarify the pathogenesis of this lesion, rat livers showing abnormal sub-lobation or lobar atrophy, rat livers in an acute dermal toxicity study and guinea pig livers in a skin sensitization test were also examined histologically. Consequently, the present lesion was considered to be a reactive change against calcium that was dystrophically deposited in the area of hepatocellular necrosis due to delayed circulatory disturbance caused by external pressure or extension force. Granulomatous lesions like in the present cases should be differentiated from those caused by evident exogenous pathogens such as chemicals or microorganisms.

Immunohistochemical and morphologic features of a cecal adenocarcinoma in a white-handed gibbon (Hylobates lar).

Cancer in nonhuman primates, especially gastrointestinal cancer, is of considerable interest from the viewpoint of comparative path~logy.~J~ Carcinoma of the large bowel is fairly common in humans8J2 but rare in nonhuman primate^.^.^ An exceptional number of colonic carcinoma cases have been observed in some colonies of cotton-top tamarins (Saguinus oedipus oedi~us);~.’ however, only a few cases have been reported in other species such as macaques, and there are no reports of such cancer in gibbons. This report describes a tumor with the histologic appearance and immunohistochemical staining characteristics of a cecal adenocarcinoma in a white-handed gibbon (Hylobates lar). An approximately 20-year-old female white-handed gibbon kept in the Higashiyama Zoo in Nagoya City5 was examined because of anorexia, weight loss, and diarrhea with bleeding. Her physical condition did not improve with treatment, and she rapidly became anemic, depressed, and ataxic and died in a coma. The gibbon was caged indoors in a family group and fed commercial monkey food and fresh fruits. Necropsy was performed immediately after death. Organs were fixed in 10% neutral buffered formalin. Tissues were embedded in paraffin, cut in 5-pm sections, and stained with hematoxylin and eosin (HE). Selected sections of the cecum with tumor were also stained with periodic acid-Schiff (PAS) or alcian blue. Deparaffinized sections of the tumor were prepared for immunohistochemical evaluation by the labeled streptavidin-biotin (LSAB) method (Dako Corp., Santa Barbara, CA) according to specific protocols. The primary antibodies against the following antigens were used: epithelial membrane antigen (EMA) (monoclonal, 1 : 20; Dako Corp.), carcinoembryonic antigen (CEA) (polyclonal, 1 : 300; Dako Corp.), lysozyme (polyclonal, 1 : 275; Dako Corp.), keratin (polyclonal, 1 : 400; Dako Corp.), and B72.3 (monoclonal, 1 : 50; Japan Tanner Corp., Kobe, Japan). Negative and substitution serum controls and positive tissue controls were employed. The specimens were counterstained with Mayer’s hematoxylin.

Gastric Adenocarcinoma in a Cougar (Felis concolor)

Diffusely invasive tumors occurred in the stomach of a 9-year-old female cougar (Felis concolor) from a zoo in Japan. The tumors consisted of tubular adenocarcinoma cells, and had infiltrative growth to the submucosa and muscularis propria. Tumor cells were positive for carcinoembryonic antigen (CEA), lysozyme, epithelial membrane antigen (EMA), gastrin, alpha-1-fetoprotein (AFP), keratin, and B72.3. Mucin-like materials occurred within cytoplasmic vacuoles.