Arteriovenous anastomoses in the cat carotid body

Summary In artery surrounding areas in the periphery of the carotid body of the cat we found arteriovenous anastomoses differing in respect to their character. So far, it is not yet to decide the frequency of their occurrence and their functional significance. The anastomoses were demonstrated by light microscopy of serial sections and by scanning electron microscopy with a more developed corrosion casting technique.

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Zusammenfassung In den arteriennahen, peripheren Bereichen des Glomus caroticum der Katze wurden arteriovenöse Verbindungen nachgewiesen, die ihrem Charakter nach unterschiedlich sind. Es ist allerdings noch nicht zu entscheiden, ob derartige Anastomosen regelmäßig vorkommen und wie sie funktionieren. Die beschriebenen Gefäßverbindungen konnten lichtmikroskopisch anhand von histologischen Serienschnitten und mit Hilfe einer weiterentwickelten Korrosionstechnik im Rasterelektronenmikroskop dargestellt werden.

     

Sympathetic innervation of the carotid bifurcation in the rabbit and cat: Blood vessels,carotid body and carotid sinus

Summary Two postganglionic branches of the superior cervical ganglion enter the area of the carotid bifurcation in the rabbit and the cat. The common and external carotid arteries receive a rich adrenergic nerve supply, which can be demonstrated by fluorophores of biogenic amines appearing after formaldehyde treatment. The internal carotid artery is only sparsely innervated; however, it shows a dense sympathetic supply at the site of pressor receptors. Following removal of the superior cervical ganglion, a total loss of fluorescent adrenergic nerves occurs and degeneration of nerve endings possessing dense core vesicles is conspicuous. These nerve terminals are situated mainly subendothelially in the carotid body sinusoids; they only rarely terminate on type I cells.     

Ultrastructural changes in the rat carotid body in severe haemorrhagia

Summary Rat carotid bodies were studied electron microscopically after short-term severe hypovolaemia, which is known to induce a marked chemoreceptor activation in the carotid body. Altogether 84 nerve-endings in the hypovolaemic rats' carotid bodies and 91 nerve-endings in the control carotid bodies were investigated. An increased accumulation of the glomus cell granular vesicles near the synaptic specializations of the nerve-endings was observed after hypovolaemia. Moreover, a statistically significant increase in the contacts between the nerve-ending synaptic specializations and the glomus cell granular vesicles was observed after hypovolaemia. A suggestion was made that the glomus cells might act as modulating, probably inhibitory, interneurones, whose catecholamines are responsible for the inhibition.The authors are greatly indebted to lecturer Pekka Korkala Ph.L. from the Department of Psychology for his skilful statistical analysis of the results.     

Lipids in the proximal convoluted tubule of the cat kidney and the reabsorption of cholesterol

Summary Lipid deposits in the cat kidney are mainly located in the epithelium of the proximal tubuli contorti, particularly in the pars contorta. As the amount of fatty acids in the blood of renal arteries is higher than in renal veins, the lipid inclusions are likely to be formed in the proximal convoluted tubule. Whether fat occurring in the urine has been released from the nephron epithelium and the mode of this release remains obscure. The structural equivalent of lipid extrusion into the tubules has not been observed.Components of the tubular lipids include triglycerides, phosphoglycerides and cholesterol. The results of the digitonin-cholesterol reaction favour the assumption that cholesterol is eliminated in the glomeruli and pinocytotically reabsorbed by the brush border cells, this process possibly serving recycling of this compound. The dilated basal labyrinth and intercellular space contain perpendicularly oriented lipid accumulations that reach the basal lamina. The ultrastructure of the lipid storing cells of pars contorta reacting positively for phosphoglyceride and cholesterol is characterised mainly by bodies with marginal plates. As far as can be judged from their morphology, these bodies are interpreted as large peroxisomes. A special feature of the pars recta are dumbbell shaped bodies and elongated or cup-like mitochondria concentrically surrounding cytoplasmic areas, as well as a well-developed smooth ER. In what way the organelles of the brush border cells are involved in catabolic and anabolic processes as far as renal lipid metabolism is concerned remains to be answered.This investigation was supported by a grant from the Deutsche ForschungsgemeinschaftThis paper is dedicated in friendship to Professor Berta Scharrer (New York) on the occasion of her 70th birthday     

Electron microscopic investigation of synaptic organization of the trochlear nucleus in cat

Summary Two distinct types of neuron in the cat trochlear nucleus (one large, one small) are described, the - and -motoneurons, respectively. Four types of terminals are observed which establish axo-dendritic synapses. Two of them (Types I and II) perform axo-somatic synapses as well. Terminals en passant (Types I and II) are predominant. The Type I terminal is long and slender with a characteristic distribution of the axoplasmic organelles and the unique feature of a relative narrowing of the synaptic cleft as compared to the width of the neighboring extracellular space. Its vesicle population is pleomorphic and a conspicuous glial barrier surrounds the synaptic zones. The Type II terminal differs slightly from Type I, revealing a wider synaptic cleft and lacking a characteristic distribution of the axoplasmic organelles. The type III terminal is rarely observed performing axo-somatic synapses, but is a common finding in the neuropil. Post-junctional dense bodies are often present in its axodendritic synapses. The Type IV nerve terminal performs axo-dendritic synapses and is characterized by a rich content of large granulated vesicles. Axo-axonal synapses are observed only very rarely.The synaptic organization of the feline trochlear nucleus is compared with the synaptic morphology of the oculomotor nuclei of inframammalian species (Waxman and Pappas, 1971). In addition to certain similarities (e.g., richness of synapses en passant), significant differences are encountered: the present study provides no morphological evidence for electrotonic transmission in the trochlear nucleus of cat.Preliminary report made at the Annual German Jahresversammlung der Anatomischen Gesellschaft, Lausanne, Switzerland, 1973.The authors wish to thank Professor R. Hassler for his valuable discussion. — Dr. W. B. Choi is on leave from the Department of Anatomy, Catholic Medical School, Seoul, Korea.     

Distribution of carotid body type I cells and other periadventitial type I cells in the carotid bifurcation regions of the rabbit

Summary The distribution of carotid body type I and periadventitial type I cells in the carotid bifurcation regions was investigated unilaterally in seven and bilaterally in two New Zealand White rabbits. Carotid body type I cells occurred in close proximity to the wall of the internal carotid artery immediately rostral to the carotid bifurcation, within a division of connective tissue with defineable but irregular borders. Caudally, and separate from the main mass of carotid body type I cells, isolated groups of periadventitial type I cells lay freely in the connective tissue around the internal carotid artery and alongside the carotid bifurcation and common carotid artery. A overall picture of the carotid body in the rabbit was reconstructed and the occurrence and significance of periadventitial type I cells discussed.The authors are indebted to Mr. Stephen Jones of the Department of Histopathology, St Bartholomew's Hospital, for expert assistance in the preparation of the material, and to Mr. A.J. Aldrich of the Department of Anatomy for photography. This work was supported by a grant from the Wellcome Trust to one of us (M. de B.D.)     

Das unterschiedliche Bild organspezifischer Strukturen im Glomus caroticum und Nebennierenmark

Zusammenfassung Die organspezifischen Strukturen im Glomus caroticum und Nebennierenmark zeigen unter verschiedenen experimentellen Bedingungen ein unterschiedliches Bild. So läßt sich unter anderem durch Modifizierung der Fixationsmedien (Glutaraldehyd, Osmiumsäure in Kombination mit verschiedenen Puffern) eine optimale Differenzierung der zellulären Strukturelemente von Glomuszellen erreichen. An den osmiophilen Vesikeln fällt eine starke Variabilität ihres Erscheinungsbildes auf. Feinstrukturelle Unterschiede werden in Elektronendichte des Vesikelinhaltes, Größe und Ausbildung des Hofes sowie in Aufbau und Verlauf der Membran deutlich. Auf Grund dieser Kriterien lassen sich im wesentlichen 4 Haupttypen der Granula von seltener vorkommenden Sonderformen abgrenzen.

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Ultrastructure of secretory granules and other specific inclusions in the carotid body and adrenal medulla

Summary The organospecific structures of the carotid body and the adrenal medulla show a different appearance under various experimental conditions. Thus, it is possible to obtain an optimal differentiation of the cellular structure elements of the carotid body cells by modifying the fixatives (glutaraldehyde, osmic acid, in combination with various buffer systems).Especially the osmiophilic vesicles show a great variability in their appearance. Ultrastructural differences become evident in the electron-density of the vesicle content, in the size of the electron-lucent space (halo of the dense core), as well as in the structure and conduct of the membrane. Based on these criteria four main types of granules can be said to occur in the carotid body. These can be distinguished from more uncommon special types.

Für technische Hilfe danken wir Frl. B. Ferdinand und Frl. B. Schmaloer.     

Adenine nucleotides in the carotid body

Summary Remarkably large amounts of adenine nucleotides are identified in type I-cells of the carotid body by fluorescence microscopy (labelling with quinacrine) and electron microscopy (uranaffin reaction). At the fine-structural level the matrix material of specific granules displays enhanced electron density after fixation with uranium ions. It is suggested that ATP is stored within specific granules in addition to catecholamines and proteins. Adenine nucleotides should be considered as one of the secretion products of the chief cells in the carotid body, being capable locally of influencing vascular flow and/or chemoreceptor terminals.Histochemical analysis of the activities leading to a splitting of adenine nucleotides shows a high reactivity with ATP or ADP as substrates. Reaction products are confined to the entire vascular bed of the carotid body. Using AMP or -glycerophosphate as substrate, practically no phosphohydrolytic activity could be detected within the carotid body. Thus, the phosphatases are adequate to remove ATP and ADP, but not to form adenosine.This study was supported by a grant from the Deutsche Forschungsgemeinschaft, Nr. Bo 525/3     

Studies on the cytophysiology of the fat body of the American silkmoth

Summary A developmental study at the electron microscopic level was conducted of the fat body cells of Hyalophora cecropia (L.). During the last larval instar the fat body increases in volume and the cells exhibit a well developed rough endoplasmic reticulum and protein bodies of diverse sizes. In the pupal fat body, the protein bodies appear to be enclosed by a double membrane and contain glycogen granules, ribosomes and mitochondrion-like structures. In addition, there are large lipid globules, cytolysomes and rough endoplasmic reticulum. The ultrastructure of the protein bodies suggests the development of large bodies by fusion of smaller protein bodies. Changes in fat body cell ultrastructure were followed during adult development and cytological evidence was obtained for the depletion of protein, glycogen and lipid in the female during this period. The female adult fat body cell contains free ribosomes, protein bodies, many mitochondria, a few lipid globules and glycogen granules. The male moth fat body cells have many mitochondria, a few glycogen granules, essentially no protein bodies, but an abundance of large lipid globules.Studies on the influence of egg maturation on the morphology of the fat body of Hyalophora gloveri (L.) revealed that ovariectomy of pupae yielded adults having more fat body than normal females, and that the fat body cells of the ovariectomized animals contained more glycogen, lipid and protein. Male pupae receiving ovarian implants developed into adults containing eggs and possessed more fat body than normal females but less than normal males. Very few glycogen granules were found in the fat body cells of normal males or males with implanted ovaries.Supported by grant AM-02818 from the National Institutes of Health.We thank Dr. James Oschman for his helpful suggestions and constructive criticisms.     

Histochemical localization of nucleoside triphosphatase activity in assimilate conducting plant tissue

Summary For the histochemical localization of nucleoside triphosphatases at the electron microscopic level, prefixed tissues were incubated with lead nitrate in addition to substrate (GOMORI reaction). While ATP and UTP as substrates gave electron-dense reaction products at the plasmalemma of sieve tubes, companion cells and phloem parenchyma cells, and at plasmodesmata in primary pitfields, AMP gave reaction products only at the tonoplast of parenchyma cells. Since electron-dense deposits also occur in cell walls and vacuoles, energy dispersive X-ray microanalysis was used to distinguish between lead deposits and lead-phosphate deposits. The latter were restricted to the symplast. Among the three plant species used, the leaf bundle phloem ofHordeum distichon showed ATPase activity largely restricted to the phloem cells, except for the thickwalled sieve tubes. Some activity also bordered the chloroplasts of the bundle sheath cells. In the C₄ plantGomphrena globosa, ATPase and UTPase activities appeared to be the greater in phloem parenchyma cells than in sieve tubes. In the phloem of youngMonstera deliciosa roots, ATPase occurred not only at the plasmalemma of sieve tubes, but also around sieve-tube plastids. When compared with AMP as substrate, it appears that nucleoside triphosphates are the natural substrates of the enzyme(s) in the plasmalemma of sieve tubes and phloem parenchyma cells.     

Calcium binding sites in the vesicles of the carotid and aortic body chief cells

Summary Chief cells of the carotid and aortic body chemoreceptors possess numerous cytoplasmic dense-core vesicles which are known to contain primarily dopamine. Following fixation in solutions containing 50 mM CaCl₂, a 20–30 nm electron-dense particle (EDP) is often observed eccentrically located in many of the vesicles. Approximately 44 % of the carotid body and 16 % of the aortic body vesicles contain an EDP. The EDP probably represents the Ca^{+ +} binding site critical to the stimulus-secretion coupling events culminating in exocytosis of these vesicles. The presence of Ca^{+ +} in the cytoplasmic vesicles was verified by electron probe X-ray microanalysis.Supported by a Grant-in-Aid from the American Heart Association (77630) and by funds contributed in part by the Texas Affiliate. The authors wish to thank Ms. Teri Heitman for her excellent technical assistance     

Observations on the fine structure,enzyme histochemistry,and innervation of parathyroid gland and ultimobranchial body of Chthonerpeton indistinctum (Gymnophiona,Amphibia)

Summary Fine structural and enzyme histochemical observations on ultimobranchial body and parathyroid gland of the caecilian Chthonerpeton are presented. The cell clusters and follicles of the ultimobranchial body consist mainly of granulated cells which are termed C-cells and obviously belong to the APUD cell series. In the larger follicles additional possibly exhausted degranulated cells and replacement cells occur. A rich supply of nerve fibres has been found in this gland. Frequently nerve terminals were observed to come into synaptic contact with the C-cells. Two categories of nerve fibres occur: a) fibres containing large polymorphic electron dense granules (probably purinergic fibres), b) fibres containing small electron transparent vesicles and a few electron dense granules (probably cholinergic fibres). The parathyroid gland consists of elongated cells (one cell type) poor in organelles and often containing fields of glycogen and lipid droplets. The cells are further characterized by fair amounts of lysosomal enzymes; they are interconnected by maculae adhaerentes and occludentes. No nerves and blood vessels have been found in the parathyroid gland of Chthonerpeton. This study has been supported by the Deutsche Forschungsgemeinschaft We 380/5.     

Nitric oxide synthase in the rat carotid body and carotid sinus

The participation of nitric oxide synthase (NOS) in the innervation of the rat carotid body and carotid sinus was investigated by means of NADPH-diaphorase histochemistry and NOS immunohistochemistry using antisera raised against purified neuronal NOS and a synthetic tridecapeptide. NOS was detected in 23% of neurons at the periphery of the carotid bodies. Some negative neurons were surrounded by NOS-positive terminals. NOS-containing varicose nerve fibres innervated the arterial vascular bed and, to a lesser extent, the islands of glomus cells. These fibres persisted after transection of the carotid sinus nerve and are probably derived from intrinsic neurons. Large NOS-positive axonal swellings in the wall of the carotid sinus were absent after transection of the sinus nerve, indicating their sensory origin. The results suggest a neuronal nitrergic control of blood flow, neuronal activity and chemoreception in the carotid body, and an intrinsic role of NO in the process of arterial baroreception.     

A comparative study of the distribution of carotid body type-I cells and periadventitial type-I cells in the carotid bifurcation regions of the rabbit,rat, guinea-pig and mouse

Summary The bilateral distribution of carotid body type-I cells was investigated in five rabbits, rats, guinea-pigs and mice by serially sectioning the carotid bifurcation regions. Carotid body type-I cells occurred bilaterally in close proximity to the wall of the internal carotid artery in the rabbit, rat and mouse and to the wall of the ascending pharyngeal artery in the guinea-pig. The rat carotid body was sometimes recessed into the lateral aspect of the superior cervical ganglion and was the most easily defined organ in the four animals studied. Caudally, and separate from the principal mass of carotid body type I cells, isolated groups of periadventitial type-I cells were observed in the connective tissues around the internal carotid artery and adjacent to the carotid bifurcation and common carotid artery in the rabbits only. An overall picture of the carotid body in the four animals was constructed. In all specimens rostral-caudal dimensions were recorded and compared bilaterally.The authors are indebted to Mr. Stephen Jones and Miss Alison Field of the Department of Histopathology, St Bartholomew's Hospital, for expert assistance in the preparation of the material; Miss J. McClelland and Miss C. Slatter for illustrations, and Mr. A. J. Aldrich and Mr. P.S. Hazell for photography. This work was supported by a grant from the Wellcome Trust to one of us (M. de B. D.)     

The myelination of the cerebellar cortex in the cat

Summary The myelination of the cerebellar cortex of the cat was investigated in 61 cats aged from 3 hrs post partum to two and a half years. The first myelinated fibers appear at the time of birth in the central medullary ray. Before the onset of myelination, all fibers reach a critical diameter of about 1 m. About the 14th day of life the number of oligodendrocytes in the prospective white matter increases markedly. Thereafter, the oligodendrocytes invade the inner granular layer. It therefore seems that the myelination of the cerebellar cortex proceeds from the central medullary ray towards the granular layer. At the 60th day of postnatal life, most of the afferent and efferent fiber systems are myelinated. These findings are discussed in relation to the development of function and the maturation of the electrical activity of the cerebellar circuit.Dedicated to Prof. Dr. H. Leonhardt in honour of his 60th birthdaySupported by the Deutsche Forschungsgemeinschaft (La 184/3)     

Transport adenosine triphosphatase activity in the rat cornea

Summary The sodium-potassium activated adenosine triphosphatase (NaKATPase) activity of the rat cornea was investigated histochemically using a Pb²⁺-precipitation technique in which adenosine triphosphate (ATP) is used as substrate and two methods for potassium-dependent para-nitrophenyl-phosphatase (K-NPPase) activity.With all the three techniques used it was demonstrated that the sodium-potassium-activated adenosine triphosphatase (NaK-ATPase) activity is localized in the cell membranes of the endothelium whereas a much weaker activity was observed in the epithelium. When the Pb²⁺-technique was used, the epithelial cell membranes showed a weaker reaction in the presence of ouabain. This activity was only Mg²⁺-dependent and was presumably due to an Mg²⁺-dependent ATPase.The validity of the histochemical techniques for NaK-ATPase activity is discussed. The results emphasize the importance of the endothelium as the main site of Na⁺ transport in the cornea. Small amounts of the enzyme are also present in the epithelium, which seems to be rich in Mg²⁺-ATPase. Provided that careful controls are performed, all the methods give consistent results in the cornea.The work is part of an eye research project by Arto Palkama and supported by grants from the Sigrid Jusélius Foundation, Helsinki, Finland, to A.P. and from the Finnish Cultural Foundation, Helsinki, Finland, to T.T. and M.P.The authors are grateful to Miss Irma Hiltunen for skilful technical assistance     

Ultrastructural localization of peroxidase activity in normal human bone marrow cells

Summary The ultrastructural localization of peroxidase activity has been studied in the cells of normal human bone marrow using the diaminobenzidine peroxidase technique. Peroxidase activity has been localized within the primary (azurophil) granules of the neutrophilic series as well as in the cytoplasmic granules of eosinophils, basophils and monocytes. Peroxidase activity appears within the cisternal system (nuclear envelope, Golgi complex and rough endoplasmic reticulum) of these cells during the period of peroxidase-containing lysosome production. With the cessation of granulogenesis, peroxidase activity disappears from the cisternal system and does not reappear in subsequent developmental stages. In cells incubated in peroxide-free media, staining of granular components, but not of cisternae, is reduced. The inclusion of catalase in peroxide-free media eliminates all staining. This indicates that an endogenous peroxide is present within the cisternae and granules of these cell types.Supported by Grant No. AM-HE-12084-12 from the National Institutes of Health, Bethesda, Maryland.Appreciation is expressed to Anita Topson and Barbara Jordan for their technical assistance and to Dr. Arthur Sagone who performed the marrow aspirations.