Fine structure of the conus papillaris in the bobtail goanna (Tiliqua rugosa)

The structure of the conus papillaris in an Australian lizard, the bobtail goanna (Tiliqua rugosa) was investigated by light and electron microscopy. In this strongly diurnal species, the conus papillaris consists of a heavily vascularized and pigmented, finger-like structure about 1 mm in diameter and 3-4 mm in length. It is situated over the optic nerve head and projects into the vitreous chamber. Within the conus are numerous capillaries and larger blood vessels, melanocytes and occasional mast cells. Many of the capillaries display prominent luminal and abluminal microfolds. Other capillaries show no microfolds while still others display an intermediate number of microfolds. The larger blood vessels are usually indistinguishable as to being either arterioles or venules. The endothelial cells of all blood vessels show a population of cytoplasmic granules. The melanocytes are large pleomorphic cells usually rich in microfilaments. Unmyelinated nerve processes are plentiful within the conus and the Schwann cells enclosing these nerve fibres are occasionally seen to be pigmented. The morphology of the conus papillaris indicates a heavy involvement in the transport of materials. It is considered to be homologous to the pecten oculi of the avian eye; to the falciform process of the teleost eye; to the supraretinal vessels of amphibians and to the intraretinal vessels of the mammalian eye.     

Microvasculature of the avian eye: studies on the eye of the duckling with microcorrosion casting, scanning electron microscopy, and stereology

The microvasculature of the eye of the duckling was studied with microcorrosion casting, scanning electron microscopy, and stereology. Most blood to the eyeball first passes through the arterial ophthalmic rete mirabile, a complex of small arteries which intermixes with a similar complex of veins (venous ophthalmic rete mirabile) at the ventrotemporal angle of the eye. The present study reveals the ultrastructural anatomy and the compact, three-dimensional arrangement of vessels in this rete, which had been shown by previous investigators to function as a countercurrent heat exchanger. Vessels from this rete include the supraorbital and infraorbital arteries, which supply the eyeball anteriorly, and the ophthalmotemporal artery, which supplies the eyeball posteriorly. The internal ophthalmic and ethmoidal arteries, branches of the cerebral carotid artery, anastomose with the ophthalmotemporal artery posteriorly. Blood is distributed to the eyeball anteriorly by two ring arteries: the iridial ring artery, which circumscribes the iris and which receives blood from the long ciliary and infraorbital arteries; and the more peripheral, ciliary ring artery, which receives blood mostly from the infraorbital and ethmoidal arteries. Within the iris is a dense, freely anastomosing bed of capillaries which extends to the edge of the pupil and then loops back beneath the ciliary body. The vasculature of the ciliary body consists of radially arranged plates of anastomosing capillaries of irregular bore which mimic the contours of that organ, but permit changes in pupil diameter. The present study demonstrates the three-dimensional anatomy of the very dense capillary net of the choriocapillaris deep to the retina and the capillary mass of the pecten, and thus supports the finding of earlier investigators that nutrients diffusing from these structures nourish the avascular retina. The pecten consists of a pleated sheet of freely anastomosing capillaries which protrudes into the vitreous body from near the optic nerve. The choriocapillaris and the pecten are supplied by branches of the ophthalmotemporal artery: the former by numerous short posterior ciliary arteries, the latter by two or three arteries which further divide into one or two smaller vessels for each of its folds. Veins of the choroid layer at the periphery of the anterior surface of the eyeball, and to some extent on its lateral walls, are revealed by the corrosion-casting technique as unusual, flattened vessels of large caliber which lie in closely spaced parallel arrays. The large surface area thus created may function in heat dissipation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Enzymhistochemische und feinstrukturelle Beobachtungen am Pecten oculi von Taube (Columba livia) und Lachmöwe (Larus ridibundus)

Zusammenfassung Im Endothel der Kapillaren des Pecten der Augen von Haustaube und Lachmöwe (Larus ridibundus) lassen sich lichtmikroskopisch alkalische und saure Phosphatase sowie Aminopeptidase nachweisen. Bernsteinsäuredehydrogenase und verschiedene Esterasen fehlen dagegen.Im Elektronenmikroskop ist das Kapillarendothel des Pecten der Lachmöwe durch dichte apikale und basale Mikrovillisäume, Mitochondrienansammlungen, zahlreiche polymorphe elektronendichte Granula, in reichem Maße vorhandene Ribosomen und multivesikuläre Körper gekennzeichnet. Zwischen Basallamina und Endothelzelle befindet sich ein weiter mit Fibrillen gefüllter Raum. Die Pigmentzellen des Pecten bilden mitochondrienhaltige Füßchen aus, die sich der Basallamina der Kapillaren anlegen. Die Oberfläche des Pecten wird von einer weiteren Basallamina gebildet; auch ihr lagern sich Füßchen der Pigmentzellen an. Die vorliegenden histochemischen und feinstrukturellen Befunde und Angaben aus der Literatur lassen vermuten, daß das Kapillarendothel im Pecten besondere Anpassungen an verstärkt ablaufende Transportvorgänge aufweist.

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Enzyme histochemical and fine-structural observations on the pecten oculi of Birds

Summary The endothelium of the capillaries in the pecten of the eyes of domestic pigeons and blackheaded gulls (Larus ridibundus) gives a positive reaction for alkaline and acid phosphatase, as well as for aminopeptidase. Negative results have been obtained for succinic-acid dehydrogenase and various esterases.In the electron microscope the capillary endothelium in the pecten of the blackheaded gull is characterized by densely packed apical and basal microvilli, accumulations of mitochondria and polymorphic electron-dense granules, numerous ribosomes and relatively common occurrence of multivesicular bodies. The endothelial cells are separated from their basal lamina by wide spaces which are filled by fibrils. The pigment cells of the pecten extend mitochondria-containing processes towards the basal lamina of the capillaries. The surface of the pecten is bound by a further basal lamina, which is underlain by other projections of the pigment cells. The present histochemical and fine-structural findings and evidence derived from the literature suggest that the capillary endothelium of the pecten shows particular adaptations in respect of transport mechanisms.

Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Vergleichende Untersuchungen an Amoebozyten und Blasenzellen von Cepaea nemoralis L. (Gastropoda,Stylommatophora)

Summary The pecten oculi of the sparrow consists of capillaries, pigment cells and a superficial membrane. Because of the loose structure of the first two components broad intercellular spaces occur in the pecten. The capillary wall consists of endothelial cells and a perivascular membrane. The bodies of the endothelial cells are flattened, while the plasmalemma of both their surfaces (basal and luminal) is strongly folded and forms numerous microfolds with an average thickness of 700 Å. The height of the inner microfolds is 1.4–1.8 m, the outer microfolds measure 1.3–1.6 m. They lie densely packed side by side and are separated by recesses of the capillary lumen ca. 500 Å wide. Due to this the surface of the endothelial cell is increased by approximately 20-fold. The adjoining endothelial cells abut or overlap with margins, and are joined by the zonulae adherentes. Pigment cells form numerous processes and microvilli. Some rest on the capillary walls, while others penetrate the superficial membrane of the pecten or fill the intercellular spaces.     

Morphology and tyrosine-hydroxylase immunohistochemistry of the systemic secondary vessel system of the blue catfish,Arius graeffei

Fish have a secondary vessel system which emerges from the primary vasculature via large numbers of coiled origins. The precise role of this vessel system is unknown. Vascular casting techniques and scanning electron microscopy reveal that the secondary vessels of the blue catfish, Arius graeffei, originate from dorsal, lateral, and ventral segmental primary arteries and from the caudal dorsal aorta. These vessels anastomose with each other to form larger secondary arteries which parallel the primary vessels for their entire length. Secondary vessels do not appear to form a capillary bed in the skin in A. graeffei as they do in some fish species. Coiled secondary vessel origins are abundant within the tunica media and adventitia of the primary vessels from which they emerge. The origins of the secondary vessels are surrounded by the extensive cytoplasmic processes of specialized endothelial cells. These processes extend for up to 6 μm into the lumen of the primary vessel. Ultrastructurally the coiled secondary capillaries consist of an endothelial cell tube which is surrounded by a single layer of pericytes. These endothelial cells extend large numbers of microvilli into the lumen of the coiled secondary capillary. Nerve terminals are commonly associated with the coiled secondary capillaries. Immunohistochemistry has revealed the presence of tyrosine-hydroxylase, an enzyme involved in catecholamine synthesis in nerve varicosities close to secondary vessels in A. graeffei. This vessel system could therefore be regulated by adrenergic nerves. © 1996 Wiley-Liss, Inc.     

Ultrastructural organization of the hamster renal pelvis.

The renal pelvis of the hamster has been studied by light microscopy (epoxy resin sections), transmission electron microscopy, and morphometric analysis of electron micrographs. Three morphologically distinct epithelia line the pelvis, and each covers a different zone of the kidney. A thin epithelium covering the outer medulla (OM) consists of two cell types: (1) granular cells are most numerous and have apically positioned granules which stain intensely with toluidine blue, are membrane-bound, and contain a fine particulate matter that stains light grey to black in electron micrographs. (2) Basal cells do not have granules, are confined to the basal lamina region, and do not reach the mucosal epithelial surface. The inner medulla (IM) is covered by a pelvic epithelium morphologically similar to collecting duct epithelium of IM. Some cells in this portion of the pelvic epithelium (IM) stain intensely dark with toluidine blue, osmium tetroxide, lead, and uranyl acetate. Transitional epithelium, which separates cortex (C) from pelvic urine, has an asymmetric luminal plasma membrane and discoid vesicles, each of which is similar to those previously observed in mammalian ureter and urinary bladder epithelia. Based on morphological comparisons with other epithelia, the IM and OM pelvic epithelia would appear permeable to solutes and/or water, while the transitional epithelium covering the C appears relatively impermeable. It would also appear that the exchange of solutes and water between pelvic urine and OM would involve capillaries, primarily, since morphometric analysis showed that both fenestrated and continuous capillaries of the OM were extremely abundant (greater than 60% of OM pelvic surface area) just under the thin pelvic epithelium.     

Clinostomum complanatum and Clinostomum marginatum (Rudolphi, 1819) (Digenea: Clinostomidae) are separate species based on differences in ribosomal DNA

Infections by metacercariae of Clinostomum (Leidy, 1856) species adversely affect aquacultured fish and are potentially transmissible to humans. Molecular methodologies are efficient tools, which enable diagnosis of all life-history stages of trematodes in their diverse hosts. The small subunit of ribosomal DNA genes of adults of the Old World Clinostomum complanatum (Rudolphi, 1819) and the New World Clinostomum marginatum (Rudolphi, 1819), obtained from a little egret Egretta garzetta (Linnaeus, 1766) and the great blue heron Ardea herodias (Linnaeus, 1758), respectively, were amplified, sequenced, and aligned. The resulting alignment was used to develop a genetic assay to differentiate between these species.     

The blood-brain barrier: an alternative hypothesis

Brain blood vessels, unlike most vessels elsewhere in the body, exhibit a blood-brain barrier (BBB) to certain substances, e.g. trypan blue. Under some circumstances this barrier is no longer effective and the permeability of the vessels increases. Although capillarization is much less in the brain than in many other organs, e.g. heart muscle, total cerebral blood flow per minute is enormous. Consequently, to accommodate a large blood volume with a limited capillary bed, the velocity of blood through brain vessels must be extremely fast. The hypothesis presented in this paper is that this rapid flow results in a low or negative pressure on the endothelium, and plasma and trypan blue are prevented from passing through the wall. The tight junctions of cerebral endothelial cells may be able to withstand only a limited amount of pressure on their luminal surface. If the velocity of blood in brain capillaries decreases, pressure on the endothelium should increase, and brain vessels, like blood vessels elsewhere in the body, become permeable to vital dyes. Other conditions also increase capillary permeability, e.g. acute arterial hypertension or venous congestion. Although brain vessels can adapt to a moderate, gradual change in systemic pressure, when a significant rise in cerebral arterial pressure is abrupt, the compensatory changes in the postcapillary venous bed may be inadequate and consequently intracapillary pressure and vascular permeability are increased. Venous congestion increases intracapillary pressure by restricting capillary outflow as well as by reducing velocity through capillary beds. Under such conditions increased capillary permeability may be indicated by cerebral edema, and even, on occasion, by petechial hemorrhages. In short, if the flow is fast and unimpeded the BBB will be effective; if the velocity decreases, or intracapillary pressure increases for whatever reason, the permeability of the brain endothelium will be abnormally increased.     

胃癌及胃壁组织内淋巴管分布的研究

本文首次用５′－Ｎａｓｅ－ＡＬＰ双重组织化学方法观察了２０例胃癌组织和癌旁胃壁组织内淋巴管的细微分布。在光镜下毛细淋巴管和淋巴管５′－Ｎａｓｅ染色强阳性,管壁显示明显的棕色或深棕色,而毛细血管和血管的ＡＬＰ反应显示强阳性,管壁呈明显的蓝色。据此可将淋巴管、血管区别开来、本研究发现胃癌组织内有较多的淋巴管、毛细淋巴管以及较多的棕色实性条状组织,这些条状物可能是新生的毛细淋巴管。上述结果为研究癌组织内淋巴管的分布及胃癌淋巴道转移,提供了可靠的实验方法。     

Arterial and venous vasculature of the heart of the beluga whale (Delphinapterus leucas)

The arteries and veins of the heart of the beluga whale (Delphinapterus leucas) are described from the dissection of nine specimens. The arterial distribution is composed of the basic mammalian pattern of two major vessels, the left and right coronary arteries, which supply the cardiac tissue. The venous drainage is provided by three major systems which are the great, middle, and small cardiac veins. The vascular characteristics of the heart of the beluga whale are the marked sinuosity of both coronary arteries and their main branches, the numerous large interarterial anastomoses between major vessels, and the duplication of vessels in parallel branches. These characteristics are discussed in functional terms and correlated with the diving ability of the species.     

Die Ultrastruktur des Conus papillaris im Auge der ErzschleicheChalcides chalcides (L.) (Lacertilia,Scincidae)

Zusammenfassung Die Strukturen des fingerförmigen Conus papillaris im Auge der ErzschleicheChalcides chalcides wurden licht- und elektronenmikroskopisch untersucht. Eine Abgrenzung zum Glaskörper hin fehlt. Das GefÄ\system gliedert sich in Arteriole, prÄkapillÄre GefÄ\e, Kapillaren und Venolen. Die Arteriole besitzt Endothelzellen mit kurzen FortsÄtzen und elektronendichten Cytosomen sowie eine locker angeordnete Muskelschicht. Die prÄkapillÄren GefÄ\abschnitte sind kurz und Ähneln im Aufbau der Arteriole. Die organellenreichen Endothelzellen der sehr langen Kapillaren weisen zürn GefÄ\lumen hin einen dichten Saum bis zu 1,2 m hoher, regelmÄ\ig angeordneter Mikrofalten auf, wÄhrend die basale ZelloberflÄche etwas weniger organisiert ist. In einer bindegewebigen GefÄ\scheide kommen PericytenauslÄufer vor. Die Venolen unterscheiden sich von der Arteriole durch eine grö\ere Zahl luminaler FortsÄtze und weniger Cytosomen im Endothel, sowie durch eine lockerer gebaute Muskelschicht. Im Interstitium finden sich Bindegewebszellen, Mastzellen und Pigmentzellen, deren Ultrastruktur beschrieben wird. Die zahlreichen marklosen vegetativen Nervenfasern enthalten auffallend wenige Schwannsche Zellen, deren Rolle formal z.T. von den Pigmentzellen eingenommen zu werden scheint. Die Nervenfasern dienen vermutlich teilweise der Innervation der zentralen GefÄ\e; andererseits kann erstmals in einem Conus papillaris auch eine Innervation von Pigmentzellen nachgewiesen werden.Die Befunde werden mit denen am Conus papillaris anderer Echsen und Pecten oculi von Vögeln im Hinblick auf strukturelle Gemeinsamkeiten zwischen beiden Organen verglichen. DerChalcidesconus entspricht in Form, GefÄ\architektur, Innervation und Mastzellgehalt dem typischen Echsenconus, wÄhrend die relative Kapillarvermehrung und die Gestaltung ihrer EndotheloberflÄche mit den VerhÄltnissen im Pecten oculi vergleichbar ist. Der Conus papillaris vonChalcides chalcides nimmt somit hinsichtlich seiner Ultrastruktur eine gewisse Mittelstellung zwischen Conus und Pecten ein. Vermutlich dient auch der Conus der ErnÄhrung der avaskulÄren Echsennetzhaut bzw. dem Austausch der intraokulÄren Flüssigkeit.

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Fine structure of the conus papillaris in the eye ofChalcides chalcides (L.) (Lacertilia, Scincidae)

Summary The conal process (conus papillaris) within the eye ofChalcides chalcides was studied by light and electron microscopy. The finger-like organ is not sharply bordered against the vitreous body. The vascular system consists of a central arteriole, precapillary vessels, capillaries and venules. The endothelial cells of the arteriole contain some luminal processes and many electron dense cytosomes. The arteriole is enveloped by a single layer of loosely arranged muscle cells. The precapillary vessels are short and in general resemble the arteriolar structure. The capillaries are forming long loops. Their endothelial cells are richly studded with cellular organelles, especially mitochondria and micropinocytotic vesicles. Their luminal surface is organized into numerous regularly arranged about 1.2 m high microfolds, whereas the basal area is developed in a similar but slightly decreased way. The capillaries are enveloped by a connective tissue vessel sheath and some pericyte processes. The endothelium of the venules differs from that of the arteriole in a higher number of luminal processes and lesser dense cytosomes. The muscle cells are loosely connected to each other forming up to 3 layers. The intervascular space of the conus is occupied by connective tissue cells, mast cells, and pigment cells. Connective tissue cells are represented by small rounded elements. Pigmented cells contain many mitochondria, some filaments, dense areas beneath the inner leaflet of the unit membrane, and they are covered in part by basement membrane-like material. Mast cells are richly supplied by specific granules, on which exocytotic processes could not be observed. The conus is innervated by numerous unmyelinated vegetative nerve fibers. Schwann cells are rare and in part seem to be replaced by pigment cells. The nerve fibers probably innervate the central vessels. In addition, for the first time an innervation of conal pigment cells is found.Our findings are compared to those of the conal process of other lizards and those of the pecten oculi within the bird's eye. Form. vascular architecture, innervation and content of mast cells resemble the situation in typical lizards' conal processes, whereas lengthening of capillary vessels and organization of the luminal surface of their endothelial cells correspond to those found in birds' pecten oculi. Therefore, the conal process ofChalcides chalcides based on its ultrastructure, seems to represent a position in the middle between the typical conus papillaris of lizards and the pecten oculi of birds. It is assumed that like the pecten the conal process serves to the nutrition of the avascular retina and/or the exchange of intraocular fluids.

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Wir danken Frau I. Schroeder und Frl. S. Seidel (Münster) sowie Herrn D. Müller (Münster) und Herrn Ch. Fiebiger (Marburg) sehr herzlich für ihre technische Mitarbeit.     

Black lesions of the skin

Benign melanocytic lesions include lentigo, ephelid (freckle), pigmented nevus, sacral spot, blue nevus, and combined nevus and blue nevus. Malignant melanocytic lesions are melanomas, which arise from melanocytes at the epidermodermal junction, or, rarely, from blue nevi. They usually originate in brown plaques known as lentigo maligna, in pigmented nevi, or in normal skin. Melanoma is diagnosed clinically in less than 50 per cent of instances. Biopsy is therefore of great importance, since practically all melanoma can be cured by adequate early resection.     

Structure of the Rete Mirabile in the Kidney of the Rat as Seen with the Electron Microscope

Electron micrographs of the rete mirabile in the medulla of the rat have revealed that the endothelium of the afferent and efferent vessels are markedly different in fine structure. The venous capillaries returning blood from the papilla are lined with a fenestrated endothelium much like that in the peritubular capillaries of the kidney. The arterial capillaries delivering blood to the papilla have an unperforated lining of overlapping endothelial cells with extremely irregular tapered margins. It is pointed out that the organization of particularly the latter vessels suggests that the functional capabilities of these retia go beyond those of a simple diffusion countercurrent exchanger.     

Actin,myosin, and laminin localization in retinal vessels of the rat

Summary Actin, myosin, and laminin have been localized in retinal vessels of normal rats by fluorescence microscopy. Actin was localized with the fluorescent F-actin binding toxin nitrobenzoxadiazole phallacidin (NBD-Ph). Indirect immunofluorescence was used to localize myosin and laminin. In addition, laminin localization was also performed with the Protein A-horseradish peroxidase (PA-HRP) method. NBD-Ph staining gave strong fluorescence in both retinal capillaries and larger vessels. Anti-myosin fluorescence could also be observed in trypsin digests of the retinal vasculature. Strong fluorescence of PA-HRP reaction product could be detected in the walls of vessels exposed to antilaminin antibody. Actin distribution in vessels of the RCS rat with inherited retinal degeneration (retinal dystrophic RCS rat) was also studied. After exposure to NBD-Ph, all capillaries showed fluorescence. However, it was more intense in many of the capillaries in the outer retina, which also appeared morphologically abnormal. Electron microscopy of retinal capillaries fixed in 2.5% glutaraldehyde containing 8% tannic acid revealed numerous micro filaments in the pericyte cytoplasm amd some in the basal portion of endothelial cells. In pericytes, these microfilaments are in close association with the endothelial side of the cell. Tangential sections through this region indicate that these filaments may be anchored to the membrane at this site.Supported by grants EY04831, Research to Prevent Blindness, Inc. and the Michigan Eye Bank     

Fine structural observations of the pecten oculi capillaries of the chicken

Summary The pecten oculi of the domestic chicken was examined with light, scanning and transmission electron microscopy and with freeze-etching techniques. Particular attention has been given to the capillary structure. The capillaries form an extensive anastomotic network. Their endothelial cells have apical (luminal), as well as basal, longitudinally oriented microfolds. It is assumed that the formation of apical differentiations of the endothelial surface is due to haemodynamic influences. Thus, sufficient surface area for membrane bound enzymes is achieved. These enzymes are necessary for active transcellular transport processes that require energy. In freeze-etched material, two different structures of the membrane surface of microfolds can be recognized. These results are discussed in relation to transport functions through capillary endothelial cells of the pecten. It is assumed that the pecten plays an important role in the nourishment of the retina and vitreous body. This paper was presented in part at the inaugural session of the European Club for Ophthalmic Fine Structure in Essen on January 20 and 21, 1973.     

Role of antioxidants in the survival of normal and vitiliginous avian melanocytes.

Mutant feather melanocytes from Barred Plymouth Rock (BPR) and White Leghorn (WL) chickens are currently being used as avian models of vitiligo. Feather melanocytes in BPR and WL chickens die prematurely in vivo due to low (50-66%) antioxidant glutathione and superoxide dismutase levels when compared to the wild type Jungle Fowl (JF) melanocytes. Excess superoxide anions, generated by xanthine:xanthine oxidase (X:XO), caused a 15-20% increase in mortality after 1 and 2 hrs. in all three genotypes of in vitro melanocytes as compared to control values that received no X:XO. Overall, the JF wild type melanocytes had the lowest mortality rate, WL melanocytes had the highest mortality rate and the BPR melanocytes had an intermediate mortality rate. Superoxide anion and hydroxyl radical production in the WL feather were double the production in the JF wild type feather. The production of reactive oxygen species in BPR was intermediate to the other two genotypes. In an effort to mimic the low antioxidant levels of the BPR and WL feathers in the JF feather, JF in vitro feather melanocytes were treated with buthionine sulfoximine (BSO), a glutathione synthesis inhibitor. With BSO added to the medium, the JF mortality rates increased by 20-25%, reaching the mortality levels of the mutant BPR melanocytes. The addition of iron to the JF melanocyte X:XO medium increased their mortality rate by 20%, probably via the Fenton reaction. Thus, antioxidants play an extremely important role in both the viability of normal avian melanocytes and the premature death of the vitiliginous avian melanocytes. A working hypothesis, supported in part by the current results, is that the premature death of the mutant melanocytes could be precipitated in the poorly vascularized feather by low antioxidant protection due to both low turnover of tissue fluids which contain SOD and to genetically determined low levels of internal antioxidant protection in these melanocytes. This same mechanistic hypothesis could apply as "a" cause of premature melanocyte cell death in human vitiligo wherein the vitiliginous melanocytes may have a genetic defect in their antioxidant protection system and blood flow to an area may be restricted.     

Helminth communities of herons (Aves: Ardeidae) in southern Italy

The helminth communities of nine species of herons from southern Italy were studied and compared. Of 24 taxa found including seven digeneans, seven nematodes, six cestodes and four acanthocephalans, only five taxa were found in more than one heron species, and five of the 21 taxa that could be identified to species level were classified as ‘heron specialists’. The total number of helminth species per heron species ranged from 1 in Botaurus stellaris to 9 in Ixobrychus minutus with infection levels generally low. A statistical comparison was carried out for herons with a sample size > 5. At the infracommunity level, only I. minutus clearly differed from other heron species. Diversity parameters of heminth infracommunities did not significantly differ among heron species. Species richness ranged from just 0.3 to 2.3 helminth taxa per individual host, and the Brillouin index, from 0 to 0.3. Total helminth abundance did not exceed 40 worms per host except in a single case of Ardeola ralloides. Infracommunities clearly were dominated by single helminth species. The present study confirms a depauperate helminth community in herons from southern Italy. Comparison with data from Spain and the Czech Republic showed strong quantitative similarities with values obtained in the present study. Results also suggest that the composition of local helminth communities are strongly variable depending on geographical location as is demonstrated by comparison with data from other European areas. However, whether herons in Europe naturally host depauperate helminth communities or these communities are depauperate because of other factors is unknown.     

5’核苷酸酶碱性磷酸酶双重染色法在毛细淋巴管研究中的应用

本文应用5’-N-ALP双重染色法观察了裸鼠皮肤及人胃癌组织内淋巴管的形态和细微分布.在光镜下毛细淋巴管、淋巴管呈5’-N强阳性反应,管壁显示明显的棕色或深棕色,而毛细血管、血管的ALP呈强阳性,管壁呈明显的蓝色.据此可用组化方法将毛细淋巴管和毛细血管区别开来.本法能显示呈褐色的毛细淋巴管,特别是呈实性条索状的毛细淋巴管,因而双重染色比HE染色更能客观、准确地显示毛细淋巴管的分布.     

The structure of lymphatic capillaries in lymph formation.

The lymphatic vascular system consists of endothelial lined vessels which begin as blind-end tubes or saccules that are located within the connective tissue areas. This system serves as a one-way drainage apparatus for the removal of diffusible substances as well as plasma proteins that escape the blood capillaries. If permitted to accumulate, these escaped components would deplete the circulatory system of its plasma colloids and disrupt the balance of forces responsible for the control of fluid movement and the exchange of gases and fluids across the blood vascular wall. The lymphatic capillaries are strategically placed and anatomically constructed to permit a continuous and rapid removal of the transient interstitial fluids, plasma proteins, and cells from the interstitium. Structurally the lymphatic capillaries consist of a continuous endothelium that is extremely attenuated over major aspects of its diameter, except in the perinuclear region which bulges into the lumen. These vessels lack a continuous basal lamina and maintain a close relationship with the adjoining interstitium by way of anchoring filaments. The adjacent cells are extensively overlapped and lack adhesion devices in many areas. When electron-opaque tracers are injected intravenously (i.e., horseradish peroxidase and ferritin), subsequent electron microscopic examination of tissues reveals the presence of tracer particles within the interstitium and the lymphatic capillary lumen. These particles gain access into the lymphatic capillaries via two major pathways: 1) the intercellular clefts of patent junctions and 2) plasmalemmal vesicles (pinocytotic vesicles). Another salient feature of the lymphatic endothelial cell includes the presence of numerous cytoplasmic filaments, which are similar in morphology to the actin filaments observed in a variety of cell types. The ultrastructural features of the lymphatic capillaries are discussed in relation to their role in the removal of interstitial fluids and particulate matter, and in the formation of lymph.     

Mate choice and imprinting in birds studied by cross-fostering in the wild

Sexual-selection theories generally assume that mating preferences are heritable traits. However, there is substantial evidence that the rearing environment may be important for the development of mating preferences, indicating that they may be learnt, or modified by experience. The relative importance of such sexual imprinting across species remains largely unexplored. Here, we report results of a large-scale cross-fostering experiment in the wild in which nestling birds were raised by parents of a different species. We show that resulting sexual imprinting may have a negative effect on pairing success in one species (the great tit, Parus major), but not in two other species (the blue tit, P. caeruleus and the pied flycatcher, Ficedula hypoleuca). A remarkable variation thus seems to exist, even between species that are congeneric and have similar breeding ecologies. The cross-fostering resulted in heterospecific pairings between the two tit species (female blue tit breeding with male great tit), which has never, to our knowledge, been previously documented. However, the chicks fledging from these nests were all blue tit.