The interaction of phagocytes and the large-sized parasite Cryptococcus neoformans: Cytochemical and ultrastructural study

Summary The yeast Cryptococcus neoformans may develop under certain conditions a large polysaccharide capsule 50–100 M in diameter and therefore cannot be phagocytosed by either polymorphonuclear cells (PMN's) or mononuclear phagocytes (MN's). The cellular defense mechanism — in various animals — against the yeast is composed by formation of ringlike structure of PMN's or MN's cells which surround the C. neoformans. Ring structures develop either in vivo or in vitro in tissue culture; destruction of the yeast occurs within 36–72 hours.Several hydrolases, such as acid phosphatase, -glucuronidase and non-specific esterase were found to be released from the phagocytic cells into the enclosed yeast. Considerable reduction of NBT used as a marker for oxidative activity was observed in MN rings at contact regions of the MN cells and the yeast. Electron microscopic studies indicate that the phagocytic cells in the ring structure have many pseudopodes penetrating into the polysaccharide capsule of the yeast. Disintegration of the capsule was observed as well as phagocytosis of its material. A possible analogy between normal phagocytosis of small-sized bodies and the ring structure obtained when large bodies are involved is discussed.     

An investigation of ageing in human costal cartilage

Summary Changes in human costal cartilage with increasing age (2–81 years) have been studied in the optical and electron microscope using routine and histochemical techniques.Concurrent with increasing age, chondrocytes undergo degeneration which is characterized initially by the accumulation of lipidic material within cells and, subsequently, by the formation of a halo around degenerating chondrocytes. The halo material is composed of electron dense bodies, amorphous material, and collagen fibrils. Both electron dense bodies and the amorphous material are of cellular origin and they have similar histochemical responses.Using histochemical techniques in the optical and in the electron microscope, it has been shown that chondroitin sulfate decreases with increasing age, while a hyaluronidase resistant material (presumably keratan sulfate) increases, initially in the central zone, and subsequently in the peripheral zones. Hyaluronidase resistant material is minute or absent in the central zone of aged cartilage.The genesis of collagen fibrils progresses from thin unbanded collagen-like fibrils in the pericellular lacunae of chondrocytes in young specimens to thick fibrils (sometimes in excess of 0.5 ) with a period of 640 Å in ageing cartilage. Aggregation of collagen fibrils seems to be related at least initially to the preponderance of matrix granules and beaded filaments which have been shown to originate intracellularly in vacuoles formed in degenerating mitochondria. Both of these structures contain glycosaminoglycans and, with increasing age, glycosaminoglycans decrease while collagen fibrils aggregate. In old age, the amorphous material, and possibly the content of disrupting electron dense bodies, seem to give origin to some collagen fibrils. This and other mechanisms of formation of collagen fibrils have been observed and they are discussed.Calcification of the matrix increases with increasing age and this agrees with previous findings.Supported by grants from the Italian National Research Council. — The authors are indebted to Miss Giuliana Silvestrini and to Mr. Lucio Virgilii for their expert and extensive technical assistance. — To Dr. A. Ascenzi, Director 1° Istituto di Anatomia e Istologia Patologica, and to Dr. C. Cavallero, Director, 2° Istituto di Anatomia e Istologia Patologica, Università di Roma, the senior author would like to express his appreciation for the use of equipment and facilities pursuant to this investigation, while on sabbatical leave from the University of California, Irvine, College of Medicine. — We wish to extend our thanks to the Italian National Research Council for supporting this study.On sabbatical leave from the University of California, Irvine, College of Medicine.     

Ovulation and the mechanism of follicle rupture

Summary The rabbit Graafian follicles are encircled by a capillary network between the theca interna and the avascular membrana granulosa. After injection of an ovulatory dose of human chorionic gonadotrophin (HCG) the theca interna cells showed an increase in the amount of smooth endoplasmic reticulum, lipid droplets and mitochondria with tubular cristae. In addition, considerably more junctions, similar to the abutment nexuses of granulosa cells were found; annular nexuses also appeared. At 4 hours after injection of HCG a prominent oedema was evident in the theca interna layer, particularly in the apical region.Small fenestrations in the endothelium of the blood capillaries increased in amount after HCG injection, and close to the time of ovulation, large gaps or perforations, 1–3 in diameter, were found in the thin, distended part of the endothelial cells. The surrounding basement membrane became fragmented and partly lost, so that a seemingly free passage from the capillary lumen to the interstitium was eventually established. Leakage of fluid, causing interstitial oedema, presumably proceeds until the pressure in the pericapillary interstitium has risen to the pressure in the capillaries. Some hours before and up to ovulation the pericapillary interstitium has also broad communications with the cavity of the follicles. Therefore, both pressure and fluid can be passed from the capillaries-via the interstitium-to the follicle antrum. However, influx of fluid with subsequent follicle expansion and ovulation-at constant pressure-does not occur until the tensile strength of the follicle wall has decreased.This investigation was supported by grants from the Swedish Medical Besearch Council (Projects No. B72-12X-78-07A, B73-12X-78-08B and B74-12X-78-09C). The technical assistance of Miss Ingalis Fransson, Miss Kerstin Nilsson, and Mrs. Ulla-Britt Westman is greatly appreciated.     

Granular “endocrine” cells in avian respiratory epithelia

Summary An electron microscopic investigation of the extrapulmonary respiratory tract of embryos and chick of the domestic fowl (Gallus domesticus) has demonstrated for the first time in birds the presence here of a small number of epithelial cells characterised by an aminecontaining type of granule. These granular cells were scattered singly throughout the trachea, syrinx and primary bronchi and seemed more numerous in the caudal part of the airway. In favourable planes of section a small part of the cell was in contact with the luminal surface of the epithelium. The characteristic granular vesicles (approximate diameter 140 nm) appeared to be randomly distributed in the cytoplasm and there was no concentration of vesicles close to the plasma membrane. One of the cells was closely associated with an intraepithelial axon. By fluorescence microscopy, a small number of cells with a similar shape and distribution to the granular cells was observed after administration of 3,4-dihydroxyphenylalanine which may indicate the presence of an amine handlign mechanism in these cells. It is suggested that the granular cells belong to the APUD system of endocrine cells and that they may be modulated by the concentration of gas in the airways.     

Regional differences in the distribution of golgi cells in the cerebellar cortex of man and some other mammals

Summary The number of Golgi cells per unit volume was determined in different regions of the cerebellar cortex of man and of ten other mammals. Despite the general belief in the uniform architecture of the cerebellar cortex, regional differences in the distribution of Golgi cells were found. In the inferior parts of the vermis, the number of Golgi cells per unit volume is twice that in the corresponding hemispheres. In addition, there are differences between the anterior and inferior parts of the vermis. These differences are a feature of the cytoarchitecture of the cerebellum in man and all the investigated mammals. The ratio of Purkinje cells to Golgi cells was also determined and found to differ in different species. In man, this ratio is 11.5, while in the monkey and cat it is almost 11.9 and in the rat 13.3. These differences in the ratio of Purkinje cells to Golgi cells are discussed from the point of view of cerebellar evolution.Supported by the Deutsche Forschungsgemeinschaft.     

Involution of the caudal musculature during metamorphosis in the ascidian,Botryllus schlosseri

Summary The caudal musculature of the free-swimming tadpole of the ascidian, B. schlosseri consists of cylindrical mononucleated cells connected in longitudinal rows flanking the axial notochord. During resorption of the larval tail, which is apparently induced by the contraction of the epidermis, muscle cells are dissociated and pushed into the body cavity where most of them are rapidly engulfed by phagocytes. In the initial stages of tail withdrawal muscle cells display surface alterations due to the disruption of intercellular junctions and disarrangement of myofibrils. Extensive degenerative changes, with shrinkage of mitochondria and disintegration of the contractile material are subsequently observed. Lysosomes and autophagic vacuoles are rarely seen and appear to play a secondary role in the degradation of the muscle cells, which occurs predominantly within the phagocytes. Myofilaments and myofibrils have never been observed within autophagic vacuoles. Clumps of muscle fragments and degenerated phagocytes undergo eventual dissolution in the blood lacunae, concomitantly with the differentiation of the young oozooid.This investigation was supported in part by a grant from the Muscular Dystrophy Associations of America and by CNR contract No. 7100396/04115542 from the Istituto di Biologia del Mare, Venice. We gratefully acknowledge the skillful assistance of Mr. G. Gallian, Mr. M. Fabbri and Mr. G. Tognon. We also thank the staff of the Stazione Idrobiologica at Chioggia for collecting the colonies.     

The ultrastructure of the sinus gland of Carcinus maenas (Crustacea: Decapoda)

Summary The sinus gland of Carcinus maenas consists of the swollen axonal endings of the neurosecretory cells of the major ganglia and acts as a storage release centre for the membrane bound neurosecretory material. These neurosecretory granules fall into five different types based on size and electron density. Their contents are released by exocytosis of the primary granules or smaller units budded from the primary granules.I thank Professor E. Naylor for his constant advice and Professor E. W. Knight-Jones, Department of Zoology, University College, Swansea, for the provision of laboratory facilities. I am grateful to the Science Research Council for the financial support. Finally, I thank the Electron Microscope Unit, Southampton General Hospital, where the work was completed.     

Ultrastructural analysis of the human cerebral ventricular system

Summary The ultrastructural organization of the human fetal choroid plexus was assessed with scanning electron microscopy. The membranous modifications of choroidal ependymal cells differ remarkably between 11 and 20 weeks of intrauterine development and suggest a variable functional capacity at different times of ontogenesis. Based upon existing data coupled with the ultra-architectural organization of cilia, clavate and linear microvilli are seen with scanning electron microscopy, a multiple functional role is hypothesized for choroidal ependymal cells.supported by USPH grant NS 08171.career development awardee K04 GM 70001     

On catecholamine-containing cells in the rat interatrial septum

Summary The interatrial septum of the rat heart contains cells which show a strong intensive-yellow paraformaldehyde-induced fluorescence. By electron microscopy these cells are characterized by an abundance of dense-core vesicles.Cholinergio axons form axo-somatic synaptic contacts with the catecholamine-containing cells. These cells, packed with dense-core vesicles, are frequently interdigitated and interconnected by zonulae and maculae adhaerentes and occludentes. The catecholamine-containing cells are surrounded by satellite cells either individually or in groups.The catecholamine-containing cells, which bear blunt, plumpish processes, can be subdivided, on the basis of position and morphology into two types. One class of cells lies within the fibroblast capsule of the intra-atrial ganglion (van der Zypen, Hasselhorst, Merz and Fillinger, 1974). A second aggregation of catecholamine-containing cells occurs outside the ganglia in close proximity to capillaries. The capillaries exhibit pores in the area of contact with the catecholaminergic cells. The structure of these catecholamine-containing cells is described and their possible function discussed.

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Zusammenfassung Im Septum interatriale des Rattenherzens treten Zellen in Erscheinung, die nach Paraformaldehyd-Bedampfung eine intensive hellgelbliche Fluoreszenz zeigen. Diese Zellen zeichnen sich durch einen großen Reichtum an dense-core vesicles aus. Cholinerge Axone bilden axo-somatische Synapsen an den katecholaminhaltigen Zellen aus. Die mit dense-core vesicles angefüllten Zellen sind oft ineinander verzahnt und durch Zonulae adhaerentes verbunden. Einzeln oder in Gruppen werden die katecholamin-enthaltenden Zellen von Satelliten-Zellen umgeben.Die mit kurzen plumpen Fortsätzen versehenen katecholaminhaltigen Zellen lassen aufgrund ihrer Lage und eines andersartigen Baues zwei Typen erkennen. Eine Gruppe von Zellen liegt innerhalb der Fibrozytenkapsel des Ganglion intraatriale (van der Zypen, Hasselhorst, Merz und Fillinger, 1974). Eine zweite Ansammlung von Katecholamin enthaltenden Zellen findet sich außerhalb der Ganglien in engem Kontakt zu Kapillaren. Die Kapillaren weisen im Bereich des Kontaktes mit den katecholaminergen Zellen Poren auf. Die Struktur dieser Zellen wird geschildert und ihre mögliche Funktion diskutiert.

     

Morphometrisch-ultrastrukturelle Untersuchungen am Nucleus supraopticus der Ratte nach Dehydratation

Zusammenfassung Der Nucleus supraopticus der Ratte, die einer Dehydratation ausgesetzt war, wurde ultrastrukturell-morphometrisch analysiert. Dabei zeigte sich, daß die relativen Volumenanteile der einzelnen Zellkompartimente während der fünftägigen Durstperiode eine auffallende Konstanz aufweisen. Hingegen läßt sich eine absolute Zunahme der Einzelzellvolumina und somit auch der an der Synthese und Sekretion der Neurohormone beteiligten Zellkompartimente feststellen. Die vorliegenden Befunde sprechen für einen beschleunigten Abtransport des neurosekretorischen Materials bei gesteigerter Synthese. Auf eine optimale Standardisierung der Perfusionsmethode bei Untersuchungen am neurosekretorischen Zwischenhirnsystem wird hingewiesen.

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Morphometric-ultrastructural investigations on the supraoptic nucleus of dehydrated rats

Summary The supraoptic nucleus of the dehydrated rat has been analysed by electron microscopy and morphometry. With that it appears, that the relative volumes of the different cell compartments are striking constant. Otherwise one can see an absolute increase of the cell volume together with the cell compartments which take part at the synthesis and secretion of the neurohormones. These results are expression of an accelerated move of the neurosecretory material during increased synthesis. The importance of an optimal standardization of the perfusion-method in investigations of the neurosecretory system is demonstrated.

Wesentliche Teile der vorliegenden Arbeit werden von H. F. Reinhardt der Medizinischen Fakultät der Universität Basel als Dissertation vorgelegt.