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The ultrastructural aspects of the paraventricular nucleus and its neuropil are described in the normal rat.

Pancreatic insulin content and insulin secretion rate evoked by glucose in incubated pieces of pancreatic tissue were measured in normal, pregnant, hypophysectomized, and chorionic growth hormone-treated hypophysectomized rats. Pregnancy failed to affect the insulin content of the pancreas and its secretory response to glucose at the 5th and 10th day of pregnancy. Thereafter (15th and 20th day) a marked increase in secretion rate wasnoticed; a small increase in insulin content was also observed. Administration of chorionic growth hormone to hypophysectomized rats induced changes in islet function comparable to those observed in late pregnancy. It is suggested that the increase in the functional activity of the beta-cell during pregnancy could be due, in part at least, to endogenous production of chorionic growth hormone. (Endocrinology 84: 41, 1969)

To investigate the extent to which whole tau proteins, structurally abnormal tau and fragments of tau are incorporated into neurofibrillary tangles in Alzheimer's disease, an immunocytochemical mapping study using a panel of antibodies to several synthetic human tau peptides has been performed. Neurofibrillary tangles were immunolabelled in situ, and paired helical filaments (PHF), the principal structural component of tangles, were immunolabelled after isolation and Pronase treatment. N-Terminal and C-terminal domains of tau were found to be present in tangles in situ. SDS-treated PHF were found to contain most of the C-terminal half of tau and were also labelled by antibodies to ubiquitin. Only some of these PHF were labelled by antisera to tau sequences towards the N-terminus, and this enabled the identification of a region of tau in which proteolytic cleavage may occur. The ultrastructural appearance of the immunolabelling suggested that both the N- and C-terminal domains of tau extend outwards from the axis of PHF. After Pronase treatment. PHF were strongly labelled only by an antiserum to PHF and by the antiserum to the most C-terminal tau synthetic peptide. The latter antiserum also strongly labelled extracellular tangles in situ, whereas these extracellular tangles were poorly labelled by the antisera to the other synthetic peptides. One anti-(tau peptide) serum labelled a population of neurofibrillary tangles in situ only after alkaline phosphatase pretreatment of tissue sections. Our results show that, although peptides along the length of the tau molecule are associated with neurofibrillary tangles in situ, only the C-terminal one-third of the molecule is tightly associated with PHF, since this region of tau is resistant to SDS treatment of PHF. We also report the existence in PHF in situ of a masked tau epitope which is partially unmasked by dephosphorylation. These results are indicative of post-translational changes in tangle-associated tau in degenerating neurons in Alzheimer's disease.

The immunoreactivity of neurofibrillary tangles (bundles of abnormal filaments) in Alzheimer's disease was compared in photonic and electron microscopy using antisera against the microtubule- associated protein tau, against isolated tangles, against ubiquitin and using monoclonal antibodies against neurofilament proteins. Only a sub-population of tangles is labeled in situ by the anti-ubiquitin serum and some tangles are unlabeled by any of the antibodies used. Double immunolabeling in electron microscopy shows, however, that ubiquitin epitopes can coexist with tau and neurofilament epitopes on a same abnormal filament. These results indicate that in situ ubiquitin immunoreactivity (and to a lesser extent tau and neurofilament immunoreactivity) is not an obligatory feature of these abnormal filaments and suggest that their antigenic composition could evolve in affected neurons.

The characterization of nuclear area, the proliferation index, and nuclear DNA content was carried out by means of digital cell image analysis, which makes it possible to compute morphometric and densitometric features on Feulgen-stained nuclei from archival, that is, formalin-fixed, paraffin-embedded materials. The 181 meningiomas studied included 173 classic (41 meningotheliomatous, 27 fibroblastic, 82 transitional, nine psammomatous, eight angiomatous and six hemangioblastic tumors) and eight malignant meningiomas (three hemangiopericytomas and five tumors that we labeled HFM, that is, tumors exhibiting evidence of histological features of malignancy). The results reveal a strong relationship between incomplete surgical resection and recurrence on the one hand and between the probability of recurrence and histopathological type on the other. Whereas neither nuclear area nor nuclear DNA content assessments were helpful in distinguishing the six classic and the two malignant meningioma subgroups, a statistically significant increase in proliferative activity was observed in the malignant meningiomas as compared with classic ones, excepting hemangioblastomas that proliferate at the same rate as the malignant meningiomas. Furthermore, the multiple meningiomas definitely proliferated more actively than the single ones, but a similar proliferative activity was observed in the nonrecurrent and recurrent meningiomas. Proliferation analyses might be therefore helpful for determining aggressive meningiomas and for planning adjuvant therapy in these cases.

Ocular bobbing and myoclonus were unusual findings in a patient with central pontine myelinolysis. Pathological findings confirmed the diagnosis of pontine and extrapontine myelinolysis.

The authors describe the clinical and pathological observations of a thoracolumbar intramedullary ependymoma. A voluminous conus of collagenous tissue was located in the center of the tumor. This most unusual histological finding is compared to rare cases of the literature describing the presence of bone and cartilage in ependymomas.

A patient with the clinical diagnosis of brain abcess presented with a CT brain scan showing an intracerebral hematoma. Subsequently bilateral spontaneous hyperdense lesions appeared. Autopsy showed the typical findings of viral encephalitis probably due to herpes simplex. It is stressed that the differential diagnosis of intracerebral hematoma includes viral encephalitis in the proper clinical setting.

An unusual case of traumatic aneurysm of the A-1 part of the anterior cerebral artery associated with a contralateral carotid-cavernous fistula is presented. Trapping of the fistula was carried out, and an attempt to repair the vessel wall was made. Thrombosis of the vessel occurred, but remained asymptomatic. Causes, physiopathology, and treatment of traumatic aneurysms are discussed.

Diencephalic syndrome of infancy occurred in an infant in whom an optic chiasma glioma was confirmed by clinical signs and histological examination. It is, to our knowledge, the first histological examination of the optic pathways and evidence of optic chiasma glioma to be reported in this syndrome.