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Silicosis, as Aschoff16) has classed it in his text-book, is an “Abkapselnde Entzundung” (encapsulating inflammation) caused by aseptic foreign bodies and represents a mesenchymal defence reaction. In the case when a granuloma is led toward formation of a typical hyaline nodule, the differentiation of the mesenchyma into capillary endothelium seems to be inhibited. The granuloma formed in the arterial wall hampers the nutritional plasma flow and thus causes the formation of the specific hyaline nodule. In this case, whether a detention of dust by collagen is postulated or not, the situation is certainly unfavorable to coalescence and the description Abkapselung (encapsulation) may be rightly applied. The acute silicosis cases apparently show an exaggerated picture of the formation of coalesced foci, and in such cases, another phlogogenic factor besides SiO2 seems to have come into play, causing a prosperous proliferation of granulation tissues and the characteristic feature of “encapsulation” above may be said severely injured. When tuberculous infection comes into combination, the caseation of the inflammation granulation brings about a peculiar pathological picture.

1. The lungs of phenyl thiourea treated guinea pigs show marked edema associated with hyaline membranes.2. Adequate edema fluid is necessary to make the hyaline membranes of guinea pigs.3. The hyaline membranes are considered as a stadium of the absorption or the concentration in pulmonary edema.4. Pulmonary edema and pneumonia are closely interrelated even in the animals.5. Pulmonary edema is a cause of death in the animals, just as atelectasis is significant in the human newborn infant.6. Pulmonary edema of human newborn infant should be carefully observed in the mesenchyma of the lungs.

Im ausgespannten vitalen Mesenterium der narkotisierten Maus last sich innerhalb der „Taches laiteuses“ (Ranvier) bei unterschiedlichster Gewebereizung (Atzstoffe, Bakterien) das Auftreten einer mesenchymalen ortsstandigen Zellform beobachten, die sich durch einen ringformigen Kern und das Fehlen cytoplasmatischer Granula auszeichnet. Diese Zellen werdenCricokaryocyten genannt. Durch weitere Transformation der Kernfigur offenbar zum Zwecke der Oberflachenvergroserung gegenuber dem Cytoplasma entstehen gelapptkernige Zellen, die in ihrerMorphe nicht ohne weiteres von segmentierten Blutleukocyten zu unterscheiden sind. Auch im Hautchenpraparat des Omentem majus vom Menschen kann eine autochthone Aktivierung der „Taches laiteuses‘ mit dem Auftreten von ringkernhaltigen Zellen gesehen werden und dies besonders dann, wenn vom Netz als Organ spezielle Leistungen der Abwehr einer Schadlichkeit gefordert werden.

Monolayer cultures of chick mesenchyma tissue were grown in media of various pH values (initially 6.0–8.5) but otherwise identical. The tissue displays a remarkable power to adjust the pH value of the medium in the direction of pH 7.5. The fastest increase in cell counts was obtained when the initial pH value was about 7.5. In some experiments, radioglucose was contained in the medium. The amount of radioactive CO 2 and lactic acid produced during incubation increased with increasing pH value. In tubes containing large numbers of cells, fermentation was more enhanced by increasing alkalinity than was respiration.

This report of a tumor of the hematopoietic system in an anaconda snake, Eunectes murinus, is the first of such a growth in a reptile. The primary site was apparently in undifferentiated mesenchymal cells in the liver and secondarily deposits occurred in the thyroid, spleen, pancreas, and kidneys. The lymphoblast was the predominant cell type in all of these organs; hence the tumor is designated as a lymphosarcoma.

Lymphopoiesis was studied by electron microscopy in the palatine tonsil of the rabbit from 18 days gestation to 5 days after birth. At 18 days tonsils formed as mounds of mesenchyma covered with epithelium. At 19 days the basal epithelial cells started to increase in number, eventually forming ‘buds‘ which projected into the mesenchyme. Simultaneously, lymphocytes appeared nearthe epithelium or buds. There was marked resemblance between the basal epithelial cells and the lymphocytes. Budding slowed down after the 25th day, but individual basal cells continued to migrate into the mesenchyme and lymphocytes increased in number. Ultrastructure wassimilar in both types of cells, and differentfrom mesenchymal cells. At 29 days lymphocytes were found in the basal epithelial layer behind an intact basement membrane. The evidence indicated that lymphocytes were derived from epithelium.

The influence of controlled damage on the growth and the energy metabolism of tissue in culture was studied. In the preparation of monolayers of chick mesenchyma tissue the time of treatment with trypsin was varied. Thereafter, the cells in the roller tubes were counted at time intervals. At first, fewer cells were found in the tubes where trypsin treatment had been more prolonged, but after 5 days all cell counts were similar. The production of CO 2 and lactic acid from radioactive glucose were also measured in the time interval from the third to the fifth day after treatment with trypsin. Depressed respiration and increased fermentation were found. It is suggested that the damage to respiration is, in part, compensated by an increase in fermentation.

Among the diseases of the pancreas, two predominate in frequency and severity: carcinoma of the pancreas and pancreatitis. The less frequent affections include pancreatic adenoma, the pancreatic cyst and pseudocyst, and the cystadenomas and sarcomas originating from the mesenchyma in or around the pancreas.

The myoepithelial cells are indeed a fascinating type of cell, in that they appear to belong to two widely divergent types of tissues, namely the epithelium and the mesenchyma. This two-sided nature is expressed not only by their position (on the one hand they are connected in typical manner with the secreting epithelium, whereas on the other hand they interact with the stroma and the basal membrane in the same way as smooth muscle fibres), but also by their possession of potentialities of both kinds of tissue, although these potentialities become apparent only under pathological conditions of growth. This concept is the key-note of the following paper, whose purpose is to report a comparative study of the myoepithelia of various organs. Many phenomena that were detectable and detected in only one organ, will be used to elucidate certain otherwise obscure changes in other organs. First we shall examine the normal myoepithelia of various tissues (I), then consider regressive changes (II) and hyperplasia (III), in order to apply the information thus obtained to the problem of tumors (IV, V). To some extent, therefore, this paper constitutes a continuation of my paper from 1939 “On the myothelia of the mammary gland”. Additional material has been collected since then; unfortunately, however, some of the relevant documents were lost during the war and in the post-war period.

An ultrastructural and a histochemical study of the disintegration of the human fetal palatinal junctional epithelium was carried out. Special attention was focused both on the epithelium proper as well as on participation of the surrounding mesenchyma. Epithelial autophagia was noticed in the form of inclusion bodies with cellular remnants as well as general cellular disintegration. The disintegration was correlated to the cellular activity of acid phosphatase and AS-esterase. The differences between human and non-human material were recorded and discussed. In the surrounding mesenchyma, histiocytes (macrophages) were noticed participating in the epithelial disintegration, while ordinary mesenchymal cells seemed without importance. The study of activity of alkaline phosphatase reveals that the rapidly growing ossification center of the vomer was touching the superior aspect of the epithelial junctional seams, where the epithelial disintegration starts. Based upon the findings the following sequential steps of disintegration were discussed: 1) pressure from the outside (the vomer anlage), 2) epithelial autophagia and 3) heterophagia of epithelial remnants (invading histiocytes). The ultrastructure and histochemistry of the so-called epithelial pearls were described. The intercellular substance of the palatinal processes was found to consist of hyaluronic acid and of chondroitin-4- and/or-6-sulfate. The mutual ratio of the glycosaminoglucuronoglycans was discussed.

HEMANGIOENDOTHELIOMAS are angiomatous tumors with definite evidence of malignant features, which tend to form imperfect capillaries or grow diffusely. They are composed of small channels within groups of endothelial cells, and their characteristic feature is the preponderance of cells over vessels. The name hemangioendothelioma was suggested in 1908 by Mallory. The tumor may occur on any part of the skin and may be surrounded by satellite lesions. It often ulcerates and bleeds profusely. It is described as not being tender; it is often attached to underlying tissues. The tumor is said to have a characteristic color indicative of blood spaces. The origin of the hemangiomas and hemangioendotheliomas is essentially the same as that of blood vessels in general. The angioblastic cells from the vascular layer of the mesenchyma lay down solid cords and islands which later unite to form continuous tubes. The clinical picture of hemangioendothelioma is

A histochemical and ultrastructural investigation of the early development of the adenohypophysis was carried out on a human material. Special attention was paid to an accumulation of hyaluronic acid and chondroitin-4-and/or-6-sulfate in the mesenchyma; its role in morphogenesis of the Rathke's pouch is discussed. The role of the vessels as a “critical factor” in the budding of the parenchyma and in the differentiation of secretory cells is discussed. Canalicular extensions from the original lumen of the pouch into the core of parenchymal buds, which migrate into the mesenchyma, is a new observation. The participation of canaliculi in formation of follicular structures of pars distalis is described and discussed. The primitive cell type lining the pouch is also found in the wall of canaliculi and follicular structures. The cell type is described and its role as the real progenitor cell of the adenohypophysis is discussed. Three types of colloid are noticed in pars distalis: 1. In the follicular structures, 2. in the slits or clefts caused by partial occlusion of the lumen of the pouch, and 3. mesenchymal extravasal colloid presumably representing material squeezed out from the aforementioned clefts or slits. It is concluded that the colloid contains material secreted from different types of granulated cells as well as material from the surface coat of the luminal cells.

Introduction During the period when the attention of laryngologists was chiefly focused on problems related to the structure and function of the epithelium of the mucous membrane, Schade 3 had already published his physicochemical works. He stressed the significance of the connective tissue layer and the importance of its relation to the cell. However, in our branch of medicine, his reasearch on the antagonisms in swelling between the basal substance and the collagen fiber, on the one hand, and between the cell and the connective tissue as a whole, on the other, has not met with the recognition it deserved. The same applies to his studies on the physiological cycle of mesenchyma transformations and on the change in mesenchyma reactivity connected with those phenomena. A greater interest in this matter was awakened by later experiments of other authors investigating the hyaluronic acid-hyaluronidase system (Duran Reynals, 1928; Kulonen, 1951 5 ; Zablocki

Differentiation of cartilage and chondro-osseous tissue occurs from a mesenchymal cell outgrowth in 88.4% of cultures of muscle tissue from near term rat fetuses when the following physico-chemical and nutritional conditions are present. The muscle is placed in a vessel made from demineralized rat bone matrix wetted with a plasma, which serves as a bridge between the explant and the substratum. The matrix serves as both a substratum and the delimiting area of the proliferating edge of the culture. When contact is made with the substratum, a chondroosseous morphogenetic pattern is imposed upon mesenchymal cells and their progeny. The chemically-defined medium 199 is used for the first 5 days to produce abundant outgrowth of mesenchyma which precedes all skeletal tissue differentiation. Medium 199 is replaced with the modified BGJ medium for 6 to 30 days to provide aeration, amino acids and vitamins in optimum quantities for synthesis of new cartilage matrix. High oxygen tension in the atmosphere surrounding the culture media is toxic to young mesenchymal cells and must be avoided during the initial phases of skeletal tissue development.

The aerobic production of lactic acid and of carbon dioxide from radioglucose by monolayers of chick mesenchyma tissue and of HeLa human carcinoma tissue during periods of incubation between 8 and 72 hr with synthetic nutrient medium has been measured. At the same time the numbers of the cells were counted so that the mean utilization of the glucose by single cells could be calculated. The utilization of glucose per cell and hr for glycolysis decreases, and for respiration increases, with increasing number of cells/roller tube and with increasing time; the relationship of this result to the Crabtree effect is discussed. The amounts of free energy available to the single cell per hr from the utilization of glucose were calculated. In the case of mesenchyma this amount does not change with time, irrespective of the share of respiration in the total supply of free energy. In contrast, the total supply of free energy to the single HeLa cell, after a transient increase, falls off with time, i.e. with increasing scarcity of metabolic fuel. In all cases, the supply of free energy from the glucose is far inferior to that calculated from manometric experiments of previous authors. It is suggested that the difference is covered mainly by the amino acids in the medium. In further experiments, the effects of varying concentrations of cyanide on the two kinds of tissue were studied. To judge both by the decrease in the cell numbers and by the free energy supply per cell from glucose, HeLa proved more resistant than mesenchyma. It is suggested that both the lesser adaptation of HeLa to scarcity of glucose and the higher resistance to cyanide reflect the fact that HeLa relies for its energy supply on aerobic glycolysis rather than on respiration to a higher extent than normal tissue.

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The syndrome of Ehlers and Danlos apparently is a constitutional dyscrasia of the mesenchyma, characterized by specific manifestations in the skin, joints and subcutaneous tissue, often associated with other congenital defects. Its history was initiated in 1899 when Ehlers reported on a patient to the Danish Dermatologic Society.1With the turn of the century, Morris made an indefinite presentation of a similar patient at a meeting of the Old Dermatological Society of London.2Six years later, in 1906, Hallopeau and Mace de Lepinay described the condition under the name of pseudodiabetic xanthoma.3Shortly thereafter, Cohn defined the pattern quite as it is recognized today.4In 1908, Danlos reviewed the case presented in 1906, recognized the unusual basic manifestations, corrected the misleading impressions given by the original authors in their descriptive title and, like Ehlers and Cohn, outlined the new syndrome.5The first report on the

An acid-insoluble fraction of rat dentin rapidly initiates a chain reaction in mesenchyma after allogeneic transplantation to the subcutaneous tissues. The tooth matrix induced alkaline phosphatase activity within 24 hours; cartilage appeared within 5 days; bone and bone marrow formed within 14 days. The induced cartilage disappeared within 5 weeks, but bone persisted at least 1 year.

The transplacental passage of demeton labeled with radioactive phosphorus (32P) in pregnant CF-1 mice was followed autoradiographically in frozen sections of fetal and placental tissues. The organophosphorus insecticide was injected intraperitoneally on the 14th day of gestation at a dose of 5 mg/kg. Placental tissue, fetal muscle, and osteogenic mesenchyma were heavily labeled within 20 minutes, the radioactivity decreasing with longer periods of treatment. Liver incorporated demeton maximally between one and two hours. The compound appeared to be rapidly metabolized because fetal tissues showed only trace activity after three hours.

In a study of 50 squamous carcinomas of the lower lip, 25 metastasized and 25 were successfully treated by simple resection. Lack of differentiation, a poor lymphocytic response and, in particular, the formation of a loose, alcian blue and Hale positive fibroblastic stroma were unfavorable prognostic signs.

IN the course of development the optic cup induces formation of the normal lens in overlying ectoderm and, later on, the pupil provokes formation of the cornea from ectoderm and mesenchyma. This regular scheme was described by Mangold1 in his classical review of the determination of the vertebrate eye. This scheme was also included in a more recent article by Lopashov and Stroeva2 dealing with the same question without any considerable alterations.

In Fortfuhrung fruherer Versuche uber die experimentelle Beeinflussung der Epidermolyse wird gezeigt, das Isonicotinsaurehydrazid in einer Konzentration von 50 mg-% die durch Hyaluronidase fermentativ ausgeloste Epidermolyse inhibiert. Die in destilliertem Wasser und in physiologischer Kochsalzlosung vor sich gehende Epidermisablosung wird dagegen durch Isonicotinsaurehydrazid nicht beeinflust.

To the Editor:— In his discussion of the article by Garvey and Lawrence on facial diplegia in lymphatic leukemia (The Journal, Dec. 16, 1933), Dr. R. H. Jaffe said: "While in malignant tumors metastases develop from the primary tumor by the implantation of cells derived from the primary tumor, the leukemic infiltrations develop locally from the undifferentiated mesenchyma." Many pathologists accept the fact that the local undifferentiated cells of the mesenchyma (mesodermal tissue) throughout the body participate in the provision of the leukemic elements. An example of the aborigenous proliferation of cells in leukemia is furnished by the observation that in the subcutaneous leukemic nodules the cells are not imported but produced locally. However, lymphomas found in the brain are essentially formed by immigrated cells. In my article on leukemia and the central nervous system ( Arch. Path. 2: 23 [July] 1926), to which Garvey and Lawrence made reference, I said