Sarah A. Luse

Secretion of various endocrine substances by ACTH-secreting tumors--gastrin, melanotropin, norepinephrine, serotonin, parathormone, vasopressin, glucagon.

Six cases of ACTH‐secreting tumors—which are shown to secrete additional hormonal substances—are reported. The high incidence of this phenomenon among our 15 observed cases with ACTH‐secreting tumor suggests that poly‐humoral secretion in ACTH‐secreting tumors is more common than previous reports would indicate. Although several of our cases are unique in that the particular combination of endocrine substances produced has not been previously reported, the tumor types (islet‐cell carcinoma, carcinoid, pheochromocytoma, oat‐cell carcinoma) are in general those which may be endocrine active in a variety of ways. Ectopic corticotrophin production arises principally in tumors of endocrine tissue, neuroendocrine tissue, endocrine dependent tissue and in oat‐cell carcinoma of the thorax. The possibility that oat‐cell carcinoma of the lung and mediastinum may be a more malignant variety of carcinoid tumor is not proven but should not yet be discounted.

Interaction of filipin and derivatives with erythrocyte membranes and lipid dispersions: electron microscopic observations.

The effect of the polyene antibiotic, filipin, on the morphology of erythrocyte membranes and lipid dispersions has been investigated with the electron microscope using negative staining (phosphotungstate). Filipin induces pit formation in rat and human erythrocytes; similar pits are also produced by the antibiotic in lecithin cholesterol dispersions. Pit formation requires the presence of cholesterol. Evidence is presented which suggests that the light ring surrounding each pit may consist predominately, if not exclusively, of sterol which had interacted with the antibiotic. Pits are not produced in lecithin-cholesterol dispersions by derivatives of the antibiotic which have little (perhydrofilipin) or no (irradiated filipin) hemolytic activity. Thus, the characteristic lamellar pattern of the dispersions is retained in the presence of the irradiated derivative, whereas perhydrofilipin has an effect which is apparently similar to that produced by lysolecithin. The pits produced by filipin resemble those produced in human erythrocyte membranes by immune lysis in the presence of complement but are quite different from those produced by saponin. The relevance of these observations to current concepts regarding the mode of filipin action is discussed. It is suggested that filipin may interfere with the ability of cholesterol to stabilize the bilayer configuration of phospholipids. Experiments which suggest that the sterol can function as a stabilizer are described.

In vitro effects of the nerve growth factor on the fine structure of the sensory nerve cells

Summary Dorsal root ganglia from 8-day chick embryos were explanted in semisolid media with or without a specific nerve growth factor (NGF). The ganglia were incubated for a period of 4 and 12 h and examined with the electron microscope. The presence of the NGF in the culture medium calls forth striking and rapid changes in the fine structure of the neurons. The nuclei develop an irregular contour and denser clumped chromatin in comparison with the controls. In the cytoplasm the Golgi apparatus is dilated; in some cells there is a massive increase in ribosomes associated with increased number of membranous elements of endoplasmic reticulum. Neurofilaments and neurotubules, sparse in control cultures, are already prominent after 4 h of incubation in the presence of the NGF. After 12 h, the cytoplasm of most ganglionic cells is packed with large masses of neurofilaments.

Ovarian teratoma: Ultrastructure and neural component

The ultrastructural details of a malignant recurrent polycystic teratoma of the ovary in a child are presented. It is well recognized that brain is a common component of malignant ovarian teratomas. Even at the ultrastructural level no evidence of abnormality, other than degeneration, can be detected. The perfect replication of brain, even to the blood‐glial relationships and synapses, is documented. Abnormal cilia are present on ciliated epithelium. The ultra‐structural degenerative changes in the glia and neurons are indistinguishable from age changes seen in the human brain.

ELECTRON MICROSCOPIC OBSERVATIONS ON THE HUMAN SUBSTANTIA NIGRA.

ALTHOUGH a precise histochemicall and biochemical2 characterization of melanin is not yet available, it is generally believed that the pigmented cells of the substantia nigra contain melanin.3 Although pigment in the neurons of the substantia nigra is a recent phylogenetic acquisition, it is apparently present in all adult primate~.~-5 Surprisingly, the substantia nigra of human albinos is pigmented.6 There have been a number of electron microscopic reports on the ultrastructure of melanin7-10 and lipofuscin.lli12 Since the substantia nigra and other pigmented nuclei of the human brain are inaccessible for histological study except after death, it was decided to evaluate the degree of preservation of cellular detail in autopsy material and, if possible, to study the ultrastructure of the pigment granules.

An electron microscopic study of the cerebral blood vessels of the opossum

SummaryBlood vessels of the opossum brain are paired, artery and vein, and end in a closed loop. Both anatomically and physiologically they are true end-arteries. The two limbs are enclosed within a single basement membrane and are separated from each other by an intercapillary cell thought to be analogous to the usual capillary pericytes. The similarity of this vascular arrangement to that in the rabbit placenta and in the medulla of the kidney is discussed in relation to the counter-current multiplier system.

Fixation and embedding of mammalian brain and spinal cord for electron microscopy

White matter of the brain was fixed in 1 % osmium tetroxide (Daltons fixative) to which was added saponin. It was found that adding saponin to the fixative, and following the gradual dehydration by a toluene step greatly improved preservation of myelin of the central nervous system.

A histocytologic and electron microscopic study of effusions associated with malignant disease.

The morphologic characteristics of cellular forms in serous effusions has been of continued interest during the past 80 years. Visualization of these cells has been obtained by various stains on either direct smears or sections of paraffin-embedded cell blocks. The recently available techniques of phase and electron microscopy offer additional information concerning the fine structure in the cellular constituents of effusions.

ULTRASTRUCTURE OF THE LEPTOMENINGES IN EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS.

HISTOLOGIC ALTERATIONS occurring in experimental allergic encephalomyelitis have been described in detail by light microscopy.l-6 In addition to the characteristic demyelinating lesions, a severe meningitis is commonly piesent, and this has been observed in the rat7 as well as in other species. Few studies on the ultrastructural changes in meningitis have been published so far. Nelson and associates8 have studied an experimental E. coli bacterial meningitis by electron microscopy, but apparently no report has been made on the more chronic meningitic response in experimental allergic encephalomyelitis. Our observations were made in conjunction with a study of the demyelinating lesions in this disease.O

Response of a transplantable rhabdomyosarcoma to cyclophosphamide therapy with special reference to differences in male and female mice

Cyclophosphamide (Cytoxan) was used to treat a transplantable rhabdomyosarcoma in C3H mice. Nine to 10 days after the tumor was transplanted, the mice were treated with 100 or 200 mg/kg of Cytoxan at 10‐day intervals for 3 injections. Male mice bearing this tumor responded better to therapy than female mice. The response in females was improved by ovariectomy and antagonized by estrogens.