James W. Townsend

Pathological effects of in utero methylmercury exposure on the cerebellum of the golden hamster: I. Early effects upon the neonatal cerebellar cortex

Abstract Pregnant golden hamsters ( Mesocricetus auratus ) were given either a single dose of 10 mg methylmercury/kg on gestational day 10 or daily doses of 2 mg/kg on gestational days 10–15. Cerebella of experimental and control offspring were examined by light and electron microscopy during the first month of postnatal life. Degenerative changes, characterized by accumulations of lysosomes and areas of floccular cytoplasmic degradation, were frequently observed in neuroblasts of the external granular layer (EGL) as well as in more differentiated neural elements in the molecular and internal granular layers. Pyknotic nuclei were seen singly and in groups throughout the EGL of treated animals. Developing dendrites appeared particularly sensitive to methylmercury. Affected dendrites were swollen and packed with degenerating cytoplasmic material. Astrocytes and perivascular macrophages also contained large aggregates of irregular electron-opaque debris, lysosomes, and large lipid droplets. Pathological alterations in the cerebellum were most pronounced during the first 15 days of postpartum life.

Histiocytic lymphoma in the mouse

Abstract This investigation studied the occurrence, distribution and morphology; and the transplantation, ultrastructural and in vitro characteristics of histiocytic lymphoma in the BALB/c and C57BL/6 strains of mice. The disease was more common in aged females of both strains. The liver was the major organ involved in the males and the liver and uterus were commonly involved in the females. Subcutaneous transplants readily metastasized to the lungs. Ultrastructurally the neoplastic cells resembled histiocytes and did not contain microfilaments or a basement membrane. The results suggest that this neoplasm is histiocytic in origin.

Pathological effects of in utero methylmercury exposure on the cerebellum of the golden hamster: II. Residual effects on the adult cerebellum

Abstract The long-term effects of prenatal methylmercury exposure were studied in the golden hamster (Mesocricetus auratus). Pregnant animals were given either 10 mg/kg methylmercury on gestational day 10 or 2 mg/kg on gestational days 10–15. Animals from treated and control litters were sacrificed as adults and cerebella examined by light and electron microscopy. Focal areas of astrogliosis were observed in the molecular layer of treated animals. Sequellae of previous injury, characterized primarily by abundant residual bodies, were observed in the perikarya and dendrites of granule and Purkinje neurons. Degenerative change of myelinated axons was observed. Possible hypotheses for continued neuronal degeneration in prenatally exposed animals are discussed.

The effect of ibuprofen on endotoxin-induced injury in sheep

The reversible cyclooxygenase inhibitor, ibuprofen, has been found to have beneficial effects on the hemodynamic alterations of endotoxemia in several animal species. We investigated the effect of ibuprofen posttreatment on the hemodynamic and histologic alterations of endotoxin induced injury in awake sheep. Three groups of sheep were treated with either an infusion of Escherichia coli endotoxin followed five minutes later by saline, an infusion of E. coli endotoxin followed five minutes later by the administration of 10 mg/kg of ibuprofen, or saline infusions in controls. Hemodynamic parameters were monitored for six hours, and the sheep were then observed for an additional 18 hours. Ibuprofen treatment reversed the early pulmonary hypertensive changes and early hemodynamic alterations associated with endotoxemia. Associated with the hemodynamic improvement was significant inhibition of thromboxane synthesis as measured by the stable metabolite, thromboxane B 2 . All endotoxintreated animals had histologic evidence of acute lung injury at 24 hours as manifested by pulmonary endothelial and alveolar epithelial injury. Ibuprofen treatment decreased the mononuclear and interstitial macrophage cellular infiltrate compared to endotoxin alone. These results suggest that thromboxane may be involved in the pathogenesis of the early hemodynamic derangements of endotoxemia. Endotoxemia was associated with histologic and ultrastructural evidence of lung injury. A single dose of ibuprofen did not alter the degree of histologic lung injury observed.

Pathological effects of in utero methylmercury exposure on the cerebellum of the golden hamster

Abstract Pregnant golden hamsters ( Mesocricetus auratus ) were given either a single dose of 10 mg methylmercury/kg on gestational day 10 or daily doses of 2 mg/kg on gestational days 10–15. Cerebella of experimental and control offspring were examined by light and electron microscopy during the first month of postnatal life. Degenerative changes, characterized by accumulations of lysosomes and areas of floccular cytoplasmic degradation, were frequently observed in neuroblasts of the external granular layer (EGL) as well as in more differentiated neural elements in the molecular and internal granular layers. Pyknotic nuclei were seen singly and in groups throughout the EGL of treated animals. Developing dendrites appeared particularly sensitive to methylmercury. Affected dendrites were swollen and packed with degenerating cytoplasmic material. Astrocytes and perivascular macrophages also contained large aggregates of irregular electron-opaque debris, lysosomes, and large lipid droplets. Pathological alterations in the cerebellum were most pronounced during the first 15 days of postpartum life.

Histology, Ultrastructure, Urinary Tract, Mouse

Ureter. The ureters originate from the renal pelvis and extend from the hilus of the kidneys to the dorsal neck of the urinary bladder. An intramural part of the ureter courses through the bladder musculature.

Pathological effects of in utero methylmercury exposure on the cerebellum of the golden hamster. 1. Early effects upon the neonatal cerebellar cortex.

Abstract Pregnant golden hamsters ( Mesocricetus auratus ) were given either a single dose of 10 mg methylmercury/kg on gestational day 10 or daily doses of 2 mg/kg on gestational days 10–15. Cerebella of experimental and control offspring were examined by light and electron microscopy during the first month of postnatal life. Degenerative changes, characterized by accumulations of lysosomes and areas of floccular cytoplasmic degradation, were frequently observed in neuroblasts of the external granular layer (EGL) as well as in more differentiated neural elements in the molecular and internal granular layers. Pyknotic nuclei were seen singly and in groups throughout the EGL of treated animals. Developing dendrites appeared particularly sensitive to methylmercury. Affected dendrites were swollen and packed with degenerating cytoplasmic material. Astrocytes and perivascular macrophages also contained large aggregates of irregular electron-opaque debris, lysosomes, and large lipid droplets. Pathological alterations in the cerebellum were most pronounced during the first 15 days of postpartum life.

Myoepithelioma, Salivary Glands, Mouse

Myoepitheliomas usually occur in the major salivary glands and appear in the subcutis of the ventral neck. They are seen as reddish-yellow masses, which may be solid or a mixture of solid and cystic. The cystic structures are filled with mucoid material and necrotic debris. The parotid and submaxillary are most commonly involved, whereas sublingual involvement is rare. We are not aware of any reports of myoepitheliomas in the minor salivary glands (Dawe 1979).

Histology and Ultrastructure, Salivary Glands, Mouse

The mouse, as well as many other species, has three major paired salivary glands — submaxillary (submandibular), parotid, and sublingual — and minor salivary glands (Smith 1966). The minor salivary glands are located in the oral submucosa and tongue, but are not visible grossly. All three major glands are closely associated and located in the subcutaneous tissue of the ventral neck area (Fig. 186). The submaxillary (submandibular) are the largest and easiest of the salivary glands to identify grossly. They are lobulated and extend posteriorly to the sternum and clavicle, anteriorly to the hyoid bone, and medially to overlap slightly on the median line. Submaxillary salivary glands of male mice are larger and more opaque than those of females (Fig. 186). A single excretory duct from the anterior dorsal surface of each gland opens on the floor of the oral cavity posterior to the incisor teeth (Hummel et al. 1966).