Distribution of endothelial and basement membrane markers in angiogenic tumors of the nervous system

The distribution of two endothelial cell markers Factor-VIII-related antigen and Ulex europaeus agglutinin was examined by immunoperoxidase and immunofluorescence techniques in paraffin-embedded specimens representing the three main types of angiogenic neoplasms of the nervous system, hemangioblastoma, hemangioendothelioma and hemangiopericytoma. In addition, the distribution of the basement membrane (BM) marker, laminin, was studied in the same tumors. It was found that Ulex europaeus agglutinin was a more sensitive marker of neoplastic endothelial cells than Factor-VIII-related antigen. Both markers only stained endothelial cells, while the tumor cells of hemangiopericytomas and the stromal cells of hemangioblastomas remained unstained. These findings do not support the view that the stromal cells of hemangioblastomas are derived from endothelial cells. With antiserum to laminin a typical staining pattern could be noticed in each tumor, showing the architectural relationships of the cells very clearly. In all three tumor types laminin was only found in the BM of the vessels, not in the interstices of the neoplastic cells outside vessel lumina. Therefore, the reticulin network previously found between the individual cells of hemangiopericytomas does not correspond to BM. It is concluded that both Ulex europaeus agglutinin and laminin antisera could be valuable new aids for the diagnosis of the three tumor types.     

Hemangioendotelioma epitelioide óseo frontoorbitario: presentación de un caso

Epithelioid hemangioendothelioma is an endothelial derived tumor with an intermediate malignant degree between hemangioma and angiosarcoma. It usually involves soft tissues although it has been described in other locations such as lung, liver, limph nodes and bone. Bone epithelioid hemangioendothelioma is very rare representing less than 1% of bone tumors. Skull involvement is exceptional.We report a case of a young man with a skull epithelioid hemangioendothelioma involving orbit and frontal bone.     

Microvascular abnormalities in ethylnitrosourea (ENU)-induced rat brain tumors: Structural basis for altered blood-brain barrier function

The fine structure, histometric characteristics, and permeability of microvessels were studied by electron microscopy in normal and in ethylnitrosourea (ENU)-induced glioma tissue from rats, using horseradish peroxidase (HRP) as a tracer. The tumor vessels were classified into (1) capillary buds (Type I); (2) round small to large capillaries (Type II); (3) sinusoidal or venule-like microvessels (Type III), and (4) abnormal arteriole-like microvessels (Type IV). All endothelial cells, basement membranes and periendothelial cells in the tumor tissue demonstrated changes in structure. The most striking alterations occurred in the endothelial cells; there were abnormal endothelial tight junctions, altered pinocytotic activity, and thickening. In the tracer study, the reaction product of HRP was present around some sinusoidal or venule-like microvessels (Type III) and extended to the widened extracellular spaces around the microvessels. The endothelial cells of Type III microvessels showed decreased nuclear and mitochondrial fractions, and increased euchromatin content and a rough endoplasmic reticulum fraction. The pinocytotic vesicles with the HRP reaction product in the endothelial cells were not increased in number. Fenestrations and gaps of the endothelial cells were observed. These alterations of the endothelial cells of sinusoidal or venule-like microvessels (Type III) are considered to be the main cause of breakdown of the blood-brain barrier in this tumor.     

Studies of the endothelial origin of cells in systemic angioendotheliomatosis and other vascular lesions of the brain and meninges using ulex europaeus lectin stains

Ulex europaeus agglutinin I (UEA-I) is a plant lectin which binds specifically to alpha-L-fucose moieties on the surface glycoproteins of human endothelial cells. The binding is completely inhibited by preincubation of the lectin with fucose. UEA-I can be conjugated directly to fluorescein or peroxidase and can be used to stain endothelium of paraffin embedded tissues. UEA-I staining was evaluated on normal and infarcted brain, systemic angioendotheliomatosis, metastatic epidural angiosarcoma, hemangioendothelioma, hemangioblastoma, angioblastic meningioma of both the hemangioblastic and hemangiopericytic types, and vascular meningioma. The endothelium, but not neuropil of normal and infarcted brain was positive for UEA-I. The tumor cells of hemangioendothelioma and angiosarcoma also stained. However, no staining was seen in malignant intravascular cells of angioendotheliomatosis, the stromal cells of hemangioblastoma, or pericytes of angioblastic meningioma. It is concluded that the malignant cells in angioendotheliomatosis, the stromal cells of hemangioblastoma and the pericytes of angioblastic meningioma do not produce surface glycoproteins characteristic of endothelial cells.     

Spinal cord compression through extraosseous extension of a vertebral low-grade hemangioendothelioma with histiocytoid differentiation

Herein, we report the case of a 47-year-old man clinically presenting a slow progressive loss of lower extremity functions within 8 weeks followed by an acute neurogenic bladder dysfunction. The patient exhibited high-grade paralysis of both legs with reduced sensation from dermatome Th11 downwards as well as marked spasticity of the lower extremity. Neuroradiological examinations revealed a protruding spinal tumor with extraosseous-intraspinal extension. The resected tumor mass exhibited a highly vascularized tumor with architectural complexity and high cellularity finally leading to the diagnosis of a hemangioendothelioma. Interesting was the fact that the tumor vasculature exhibited many CD68-positive cells protruding into the lumen and, therefore, being part of a partially histiocytoid differentiation which is all the more uncommon in hemangioendothelioma. The time frame of 3 hours between embolization and tumor resection is too short to explain a monocytic intravascular reaction. Usually, hemangioendotheliomas arise from the soft tissue, lungs or liver, but intraspinal manifestations are only rarely observed. Furthermore, the clinical course with a progressive development of a paraparesis due to a hemangioendothelioma is very uncommon.     

A clinicopathological study of central neurocytoma

In 1982, Hassoun et al. reported two cases of differentiated neuroblastoma with the clinical and light microscopic appearance of intraventricular oligodendroglioma and gave a name of "central neurocytoma" to this tumor. Jerdan et al. (1983) called the similar tumor as "differentiated cerebral neuroblastoma in adults". As the tumor can be diagnosed only by ultrastructural study, the established cases so far reported are very rare. In this paper we present five cases identical to those presented by Hassoun et al. and clarify the essential nature of this new category of brain tumors. All of our cases of central neurocytoma occurred in the lateral ventricles of young adults. Clinically there was no evidence of leptomeningeal or ventricular dissemination of tumor cells. After subtotal resection of the tumor and 6000 rads of whole brain irradiation, the tumor mass disappeared and no evidence for recurrence of the tumor was noted on CT scan. All cases showed almost the same histology. The tumor cells contained a small round and/or oval nucleus, and had eosinophilic thin delicate cytoplasmic processes. There were no Homer Wright rosette, but were anuclear spaces consisting of fine fibrillar structures, like so called "broad rosettes" or "large rosettes". Capillary mesh was found among the tumor cells, but there was no endothelial proliferation. The tumor cells were monotonous, lacking pleomorphism, mitotic figures, and necrotic foci. Calcifications were observed in two cases. In the areas where the tumor cells arranged loosely, cytoplasms became clear, showing perinuclear halo, like those of oligodendrogliomas. Immunohistochemical examination showed GFAP and vimentin positive cells were all reactive astrocytes around capillaries and near calcifications. No tumor cells contained GFAP and vimentin. The tumor cells were also negative for neurofilament both of 70 KD and 200 KD. NSE was more or less positive for tumor cell cytoplasm as well as fine fibrils. Anti-Leu7 antibodies stained only fine cytoplasmic processes, but not cytoplasm. Some reactive astrocytes were stained with anti-Leu7 antibodies. Electron microscopic examination showed nuclei of the tumor cells were roughly round or oval without nuclear indentations and contained finely dispersed nuclear chromatin. In the cytoplasm, there were numerous free ribosomes, mitochondria, Golgi apparatus and electron dense various-shaped granules. Microtubules were found in the periphery of the cells, but filamentous structures were not identified.(ABSTRACT TRUNCATED AT 400 WORDS)     

Olfactory neuroepithelioma arising from the olfactory placode

The patient was a 54-year-old man, who had lost his sense of smell 6 years previously and had started to become forgetful about 6 months prior to presenting at hospital. MRI admission showed a large multicystic tumor with Gd-DTPA enhancement extending from the anterior cranial fossa through the sphenoid sinus and into the nasal cavity. Histopathological examination revealed extensive proliferation of small round cells that were divided by connective tissue septae. The tumor cells occasionally formed tubular structures, although no basement membranes were present. On immunostaining, round tumor cells were positive for neuron-specific enolase, synaptophysin, and chromogranin A, while cells forming tubules were positive for AE 1 and CAM 5.2. Almost all of the tumor cells were positive for Ber-EP4, and some of the epithelioid cells surrounding the tubular structures were also positive for luteinizing hormone-releasing hormone (LH-RH). Electron microscopy demonstrated sporadic intercellular junctions, many microtubules in the tumor cell processes, and clear- and dense-cored vesicles in the cytoplasm. Based on the results, this case appears to be the first documented neuroepithelioma with Ber-EP4- and LH-RH-positive cells arising from the olfactory placode.     

Tubular bodies (Weibel-Palade) in the endothelial cell of glioblastoma

Authors have studied the ultrastructure of endothelial cells in the microvessels of malignant and benign gliomas and in particular, the numbers of tubular bodies (Weibel-Palade) in endothelial cells of glioma microvessels in related with blood vessel proliferation. Glioblastoma 6, astrocytoma grade II 1, oligodendroglioma 1 and 2 samples of non-tumor brain tissue were analyzed quantitatively using light and electron microscope with Karnovski fixative. All tissues were obtained from the center, the intermediate and the margin in each tumor tissue and just outside of the tumor at operation. 389 microvessels were examined in the total gliomas electronmicroscopically. Tubular body was first described by Weibel and Palade in the vascular endothelial cells of various organs in both man and animals. This is now considered to be an organelle specific to the endothelial cell, but its function is still unknown. Tubular body observed in the endothelial cells of the gliomas vessels consisted of a membrane-limited round, oval or elongated shaped intra cytoplasmic body (about 0.1-0.2 micron) which contained tubules of 150-200 A outer diameter. Tubular bodies were classified in the two types. One of them (mature type) was relatively electron dense to be more compact, the other (immature type) had relatively pale matrix. In the immature type they are located in close proximity to the Golgi complex or endoplasmic reticulum.(ABSTRACT TRUNCATED AT 250 WORDS)     

Affinity cytochemistry of vascular endothelia in brain tumors by biotinylated Ulex europaeus type I lectin (UEA I)

Summary The vascularization of 50 tumors of the central nervous system (CNS) including 17 meningeomas, 25 neuroectodermal tumors, i.e., astrocytomas, oligodendrogliomas, mixed gliomas, glioblastomas, medulloblastomas, seven metastatic carcinomas, and one malignant hemangioendothelioma were investigated using biotinylated Ulex europaeus type I lectin (UEA I) in an indirect avidinbiotin-peroxidase procedure. The cytochemical staining pattern of UEA I on paraffin sections was compared with that of biotinylated Dolichos biflorus lectin (DBA), and with the immunocytochemical staining of factor VIII related antigen (F VIII/RAG) by polyclonal antisera using the PAP technique. UEA I visualized the endothelia of blood vessels with equal intensity, sensitivity, and reliability in normal brain and in tumor tissue with neovascularization. While large, medium, and small vessels were equally well demonstrated by UEA I and antibodies against FVIII/RAG, capillaries and endothelial sprouts were stained more consistently and intensely by UEA I. No reliable cytochemical staining could be obtained by DBA regardless of tissue or cell type investigated.It is concluded that UEA I is a highly useful cytochemical marker for the identification of vascular endothelia in paraffin sections of human brain tumors.Dedicated to o. Professor emeritus Dr. Dres. h. c. Hubert Meessen on the occasion of his 75th birthday     

Rosette‐forming glioneuronal tumor of the fourth ventricle with advanced microvascular proliferation – a case report

Rosette‐forming glioneuronal tumor (RGNT) of the fourth ventricle is a recently described novel type of primary brain tumor that was included into the current WHO classification of CNS tumors. It is a very rare, slowly growing, mixed neoplasm at cerebellar localization with distinctive morphological pattern. We present an unusual case of a 20‐year‐old patient with RNGT of the fourth ventricle with advanced microvascular proliferation. MRI revealed the solid‐cystic tumor mass largely involving the cerebellar vermis and left hemisphere with compression of the fourth ventricle. Microscopically, the tumor showed classical architectural pattern with two distinctive components. The main component consisted of neurocytic rosettes formed by round, isomorphic nuclei arranged around eosinophilic, fibrillar cores with strong synaptophysin expression. The perivascular rosettes with cell arrangement along blood vessels were observed only sporadically. The second neoplastic component consisted of spindle or stellate astroglial cells with piloid process and Rosenthal fibers, strongly resembling pilocytic astrocytoma. Focally, the astroglial cells showed increased cellularity but without marked nuclear atypia. The glial part of the tumor revealed advanced proliferation of microvessels. The vessels of glomeruloid type exhibited multilayered endothelial proliferation and marked mitotic activity. MIB1 labelling index was generally low; however, in areas exhibiting microvascular proliferation its expression was significantly increased up to 20%. This report demonstrates the unique case of RGNT with conspicuous microvascular proliferation of glomeruloid type and extensive endothelial proliferation. As there is still limited clinical experience with RGNT, further studies are necessary to evaluate the biology of this type of tumor.     

脑膜恶性黑色素瘤病三例临床病理及神经影像学特点

目的 探讨脑膜恶性黑色素瘤病的临床、病理及神经影像学特点.方法 对我院收治的经病理确诊的3例脑膜恶性黑色素瘤病患者进行观察,总结其临床、脑脊液细胞学、神经影像学、脑膜组织病理等方面特点.结果 3例患者均以头痛起病,随后出现脑膜刺激征.其中1例皮肤有巨大黑色素痣,1例额部黑痣破溃经久不愈,另一例无皮肤及内脏黑色素瘤,为原发性.3例患者颅脑MRI强化后显示软脑膜及蛛网膜弥漫性较均匀强化并增厚.脑脊液可见大最的异形细胞.脑膜呈黑褐色或深棕色,光镜下肿瘤细胞呈多形性,核大而圆或呈不规则形,胞质丰富,核分裂象可见,胞质内黑色素颗粒聚集,细胞排列紊乱.免疫组织化学分析S-100蛋白、波形蛋白、黑色素瘤抗体HMB-45等胞质反应阳性.结论 脑膜恶性黑色素瘤病临床主要表现为头痛及脑膜刺激征,脑脊液可见大量的异形肿瘤细胞.脑膜病理见肿瘤细胞胞质内黑色素颗粒聚集、瘤细胞排列紊乱.颅脑强化MRI对该病的诊断具有一定价值.     

Glioblastoma with large numbers of eosinophilic hyaline droplets in neoplastic astrocytes

We report a case of glioblastoma with unusual histological features arising in the left frontal lobe of a 79-year-old woman. On routine histological examinations of specimens obtained at the surgical resection, the tumor was consistent with glioblastoma, and intracytoplasmic inclusions of bright eosinophilic, round objects were found in a large number of neoplastic astrocytes. Pathological studies using histochemical/ immunohistochemical stainings and electron microscopy demonstrated that the inclusions were compatible with eosinophilic hyaline droplets (EHD), which are predominantly seen in pleomorphic xanthoastrocytoma and pilocytic astrocytoma. EHD-bearing cells were distributed throughout the tumor tissue and focally abundant (182/mm2). Most of those cells were negative for MIB- I immunostaining, although mitotic figures were rarely observed. Neither round granular body nor Rosenthal fibers were seen. Based on these neuropathological findings and a review of the literature, we concluded that this case was a very rare case of glioblastoma with numerous EHDs. The presence of numerous EHDs is considered a diagnostically helpful feature suggesting low-grade astrocytomas. The present case suggested that diagnostic application of numerous EHDs should be careful, particularly in small biopsy samples such as stereotactic biopsy.     

Identification of Lyve-1 positive macrophages as resident cells in meninges of rats

Meningeal immunity along with its associated lymphatic vasculatures is widely discussed recently. Lymphatic vessels in meninges drain interstitial fluid into the deep-cervical lymph nodes. The vessels are composed of cells that express the cardinal marker for lymphatic endothelium—the lymphatic vessel hyaluronan receptor-1 (Lyve-1). However, studies also show the presence of nonendothelial Lyve-1 expressing cells in certain tissues. Therefore, we were curious if nonendothelial Lyve-1+ cells are also present in dura mater of meninges. We show that Lyve-1+ endothelial cells are distributed adjacent to the blood vessels in the brain dura mater of rats. We did not observe any lymphatic vessels in spinal dura mater. Interestingly, we also observed isolated population of nonlymphatic Lyve-1+ cells in both brain and spinal dura mater. Morphologically, the Lyve-1+ cells were extensively pleomorphic, sometimes elongated or round. Surprisingly, the thoracolumbal meningeal Lyve-1+ cells were predominantly round in morphology. Using endothelial specific marker VEGFR3 and macrophage markers CD68 and CD169, we observed that the isolated Lyve-1+ cells lacked endothelial cell signature, but were either CD68+ or CD169+ macrophages. Moreover, we observed that the Lyve-1+ cells colocalized with collagen fibers in the meninges, and some of Lyve-1+ cells had intracellular collagen. The study for the first time demonstrates the presence of Lyve-1 positive macrophages in the lymphatic and nonlymphatic regions in the meninges of rats.     

Anaplastic and meningothelial meningiomas in a single tumor: A “dedifferentiated meningioma”?

The patient was a 74‐year‐old man, who developed progressive cognitive impairment and gait instability. Neuroradiological examination demonstrated a large and predominantly extra‐axial tumor spreading over the bilateral frontal base, indicative of olfactory groove meningioma. The greater part of the resected tumor consisted of a dense, patternless proliferation of large, round or polygonal cells, and compactly fascicular growth of spindle cells. Tumor cells showed markedly anaplastic cytological features. In small areas of the tumor, a typical meningothelial meningioma showing no cellular atypism was found. Both tumor components were closely juxtaposed and no pathological features of an intermediate grade (atypical meningioma) were noted. Shortly after the operation, the patient developed a local recurrence of the tumor and multiple metastases to the cerebrum, bone and skin. Anaplastic meningioma is a rare, highly malignant neoplasm which arises de novo or as a result of the progressive transformation of a low‐grade meningioma. The coexistence of anaplastic and low‐grade components in a single meningeal tumor has been rarely reported. This dimorphic appearance is reminiscent of “dedifferentiation”, a phenomenon infrequently seen in various mesenchymal and salivary gland neoplasms. We think that the term “dedifferentiated meningioma” can be appropriately applied to tumors such as that reported herein.     

Primary epithelioid hemangioendothelioma in the clival region: A case report and literature review

Epithelioid hemangioendothelioma (EHE) is a rare and low‐grade vascular tumor, which usually occurs in the soft tissue, liver, breast, lung and skeleton. Here we submit a case with EHE of the clival region. A 58‐year‐old woman was admitted with a medical history of 3 months headache and 1 month visual deterioration. MRI revealed a well‐circumscribed mass of 4.0 cm × 3.0 cm with bony invasion. The tumor was subtotally removed in a piecemeal fashion. Histologically, the tumor was composed of epithelioid cells with eosinophilic cytoplasm and intracytoplasmic vacuoles. Immunohistochemically, the tumor cells were positive for the markers CD31, CD34, factor VIII and vimentin. The pathological result was interpretated as EHE of the clival region. EHE is an uncommon vascular tumor, which is rarely seen in the clival region. Definitive diagnosis depends on histopathologic and immunohistochemical features.     

Histological study of malignant cerebral granular cell tumor

Granular cell tumor (GCT), which is suspected to be of Schwann cell origin, sometimes grows in the subcutaneous tissue, oral cavity and visceral sites and this tumor has a rather benign nature. Intracranial GCT also grows in the neurohypophysis but rarely in the brain parenchyma. We reported a case of intra-cerebral GCT in the left hemisphere, which took a malignant course. The patient was a 62-year-old male with a history of slowly progressing right hemiparesis and aphasia since May 1986. He was in a drowsy state and showed right hemiplegia on admission (October 14, 1986). Radiological examinations revealed a tumor and surrounding edema in the left temporal lobe and basal ganglia . Resection of the tumor and both radiotherapy of 53 Grey and chemotherapy using ACNU (total 310 mg) and BrdU (500 mg, two times per week prior to radiation) were applied after the operation. Although the tumor disappeared once after these treatments, the patient died of recurrence on July 3, 1987. Histological examinations on the specimen taken at the first operation revealed that the tumor consisted of rather round, large and small cells with a few cell processes. The large cells often had bizarre and multiple nuclei. These large cells had rich eosinophilic granular particles of various size and vacuoles in their cytoplasm. The staining for antiglial fibrillary acidic protein (GFAP) was positive in a part of the cytoplasm and cell processes. Electron microscopically various sized and shaped granular structures and intermediate filaments were noticed in the cytoplasm of both large and smaller cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

The ultrastructural study of primary intracranial germ tumors

We describe here ultrastructural and clinicopathological features of five primary intracranial germinomas. By electron microscopy, two major tumor components were defined as large, well differentiated tumor cells and non-neoplastic cells such as macrophages, astrocytes and lymphocytes. Nuclei of tumor cells were round to oval, often presented irregularly contoured nuclear membranes with oval indentations and, occasionally, cytoplasmic invagination. Some of them constituted unusual conformational changes of nuclear membranes rarely described as intranuclear pockets. Desmosome-like intercellular junctions were observed in several neoplastic cells. The nucleoli were composed of a loose, fragmented nucleolonema, whereas elongated, anastomosing and rope-like nucleolonemas, described previously as characteristic for germinomas were not seen. Most tumor cells had villous cytoplasmic projections sometimes intermingled with similar projections of macrophages. Cytoplasm contained a moderate number of mitochondria, a few lysosomes, annulate lamellae, centrioles and glycogen particles. The other distinct components of tumor were lymphocytes, macrophages and astrocytes. Scattered astrocytes typically contained abundant glial filaments adjacent to primary tumor cell. A filopodia-like processes of macrophages often interspersed between other cells, were very prominent features of germinomas. Small lymphocytes were found scattered between the tumor cells, single or in clusters.     

Epithelioid schwannomas of the acoustic nerve

Epithelioid schwannomas occur predominantly in relation to peripheral nerves and are associated with histological and clinical malignancy. However, a variant of the epithelioid schwannoma involving cranial nerves is extremely rare. In this study we report three cases of epithelioid schwannomas originating from the acoustic nerves and located in the cerebello-pontine angles. In the first case, the tumor was histopathologically entirely solid and demonstrated biphasic pattern with both spindle-shaped cells and a population of round or polygonal epithelioid cells. The second one consisted of the smaller part exhibiting typical Antoni B and A tissue and large areas containing clusters and bundles of epithelioid cells. Purely epithelioid schwannoma composed predominantly of cords or nests of round and polygonal epithelioid cells were observed in the third case. All schwannomas revealed marked polymorphism and nuclear hyperchromasia. Immunohistochemical studies showed a diffuse, strong positivity for S-100 protein in the cytoplasm of the spindle and epithelioid tumor cells. These two populations of cells were positively stained for vimentin, but were negative for EMA, cytokeratin and HMB45. Patchy GFAP-immunoreactivity was also noticed at the peripheral parts of the tumors. The authors discuss differential diagnosis of this unusual variant of schwannoma in relation to malignant transformation of the epithelioid component.     

Meningioma with eosinophilic granular inclusions

Rare meningiomas have been described that contain eosinophilic inclusions that have a granular or granulofilamentous ultrastructure. We describe a 66-year-old woman who developed a planum sphenoidale meningioma. Histologically, the tumor was composed of meningothelial cells arranged in fascicles and whorls, typical of a well-differentiated meningioma. Many tumor cells contained round intracytoplasmic eosinophilic inclusions that were periodic acid Schiff-negative and red on Masson trichrome. The inclusions were immunopositive for vimentin, and were immunonegative for epithelial membrane antigen, smooth muscle actin, desmin and type IV collagen. Ultrastructural examination showed the inclusions were composed of round to oval, well-demarcated, non-membrane-bound, osmiophilic granular material. The inclusions within this tumor had histochemical, immunohistochemical and ultrastructural properties not described in other reported meningiomas with eosinophilic granular or granulofilamentous inclusions.     

Cytochemical study of Mg2(+)-ATPase and ALPase activity in human meningiomas

Ultracytochemical features of microvessels and tumor cells of the human meningiomas were examined by light and electron microscopy with special reference to the distribution of Mg2(+)-ATPase and alkaline phosphatase (ALPase) activity on the walls of the vessels and tumor cell surfaces. Materials used were 4 cases of meningiomas, 2 of which were meningotheliomatous type, one fibroblastic type and one malignant meningioma respectively. For ultracytochemistry, specimens were quickly fixed in an ice-cold 0.1 M cacodylate buffer containing 8% sucrose (pH 7.2) for one hour and transferred to a substrate solution for detection of Mg2(+)-ATPase and ALPase. The preparations were incubated at 37 degrees C for 15-30 min in the medium described by Mayahara et al. for ALPase and for 15-20 min in the medium described by Wachstein and Meisel. The control samples were incubated in a medium containing 1 mM Bromotetramisole for ALPase and also in a substrate free medium for Mg2(+)-ATPase. At the light microscopy, Mg2(+)-ATPase and ALPase activities appeared to be mainly restricted to the capillary wall and around or in the tumor cell nest showing whorl formation. Both enzyme activities were negative in the control study. By electron microscopy, reaction products representing Mg2(+)-ATPase activity were distributed in the basolateral plasma membrane of the endothelial cells on the surface of the pericytes and on the surface of the tumor cells. Reaction products of ALPase activity located mainly on the abluminal surfaces of the endothelial cells and in some specimen on both luminal and abluminal surfaces of those cells. Intense reaction products were distributed evenly on all round surfaces of the tumor cells.(ABSTRACT TRUNCATED AT 250 WORDS)