bluuebunny/crossref_metadata_2025 huggingface dataset:
The Structure of the Hypothalamohypophysial Portal Vascular System in Acipenser ruthenus L. (Chondrostei)
Authors: Hansen Georg Nørgaard
Published: April 2010

The vascularization of the pituitary region in Acipenser ruthenus L. (Chondrostei) is described. The adenohypophysis has no direct arterial supply but is fed exclusively by a pituitary portal system supplied through a pair of infundibular arteries. Distinct portal vessels connect the lateral part of the primary plexus of the neurohaemal area (the median eminence) with the secondary plexus of the pituitary gland. The primary plexus enters the pars distalis paramedially, apparently without the formation of distinct portal vessels. The neuro‐intermediate lobe receives its blood supply exclusively from the primary plexus. The plexus intermedius gives off capillaries to the parenchyma of the intermediate lobe (an intermediate lobe sinus system). The saccus vasculosus receives (1) a “direct” supply, i.e. branches originating directly from the cerebral arteries and (2) an “indirect” supply, i.e. capillaries from the primary plexus. The pars distalis is drained into an unpaired ventral hypophysial vein, while a dorsal hypophysial vein, also unpaired, drains the plexus intermedius. These two veins join to form the unpaired hypophysial vein. The findings are discussed from comparative and functional viewpoints.
The Olfactory System in the Hagfish Myxine glutinosa
Authors: Holmberg Kaj , Lundin Vanja
Published: April 2010

In the hagfish Myxine glutinosa nerve fiber bundles in the lamina propria of the olfactory lamellae run dorsally and collect to form dorsal nerves which posteriorly enter the olfactory bulb. The nerve fibers in the lamina propria and in the transitional regions between the lamina propria of each lamella and the dorsal nerves display two different appearances: 1. Small fibers (olfactory axons) range approximately between 85 and 165 nm in diameter; the cytoplasm is more electron dense than that of large fibers; one or a few microtubuli are frequently seen in the cytoplasm, whereas mitochondria are seldom observed; 2. Large fibers range approximately between 500 and 1200 nm in diameter; the cytoplasm is electron translucent and mitochondria occur frequently. Nerve fibers in the dorsal nerves have a diameter of 100 to 500 nm and within a nerve bundle they are grouped in fasciculi with an estimated fiber density of 16/μm2. Figers with diameter exceeding 500 nm are very seldom seen in the dorsal nerves.

The small fibers are with great certainty olfactory receptor cell axons, since their size, fine structure and organization in fasciculi is entirely similar to that described in other species. The structure and distribution of large nerve fibers are discussed with regard to the possibility that they either are efferent fibers which constitute an extrinsic innervation of the olfactory epithelium or are the axons of olfactory receptor cells.
Radioautography of Presumptive Interrenal Cells in the Sea Lamprey After 3H‐cholesterol Injection
Authors: Youson John H.
Published: April 2010

Abstract Radioautography demonstrates that the injection of 3H‐cholesterol into larval and adult sea lamprey, Petromyzon marinus L., results in labelling of their presumptive interrenal cells. This localization of cholesterol and/or its metabolites is: (1) further evidence for the homology of these cells with adrenocortical cells of higher vertebrates and (2) a suggestion of the possibility that these cells in lampreys are able to absorb cholesterol for utilization in corticosteroid synthesis.
Untersuchungen zum circadianen Sekretionszyklus der neurosekretorischen Kerngebiete der Maus*
Authors: Martin Dieter , Luppa Hans
Published: April 2010

Abstract Investigations on the circadian cycle of secretion in the neurosecretory nuclei of mouse. The circadian cycle of secretion of both hypothalamic neurosecretory nuclei N. supraopticus and N. paraventricularis in mice was studied by histological, histochemical, biochemical and electron‐microscopical methods. Both areas undergo a circadian secretion cycle (24 h‐rhytm).

The activity of metabolism increases at the beginning of night, whereas by day the cells are considered to be in a phase of restitution and transportation of the secretion. Especially increases the volume of the cell nuclei (synthesis of RNA and proteins) and the activity of the extralysosomal unspecific esterase rises to maximal values.

From midnight till the beginning of the light‐phase the cells show a maximal volume of the nuclei and an increased secretion as well as higher activity of acid phosphatase and lactate dehydrogenase. Unspecific esterase activity, on the other hand, diminished. There was a noticable increase in the quantity of neurosecretion in both areas, it reached a maximum at the beginning of the light‐phase, whereas the volume of the nuclei and the activity of acid phosphatase and thiamine pyrophosphatase diminished. The neurosecretion is more and more transported to the hypophysis. The cells restitute during the light‐phase and reach their starting level.
On the Presence of a Transverse System in Tunicate Muscle
Authors: Bone Q. , Ryan K. P.
Published: April 2010

Abstract Ultrastructural investigation of the caudal muscle cells in the tadpole larva of the ascidian Dendrodoa grossularia has shown that in this species, a transverse tubular system is present; diad and triad couplings are formed with the sarcoplasmic reticulum. Peripheral couplings of the sarcoplasmic reticulum are infrequent and have only been observed at the longitudinally apposed faces of the caudal muscle cells.
The Occurrence of a Gizzard in a Bryozoan of the Order Cheilostomata
Authors: Gordon D. P.
Published: April 2010

Abstract A gizzard is recorded for the first time in a bryozoan, Hippothoa divaricata var. conferta, of the order Cheilostomata.
Seasonal Changes in the Newt, Trituroides hongkongensis, Testis. II. An Ultrastructural Study on the Lobule Boundary Cell
Authors: Tso E. C.‐F. , Lofts B.
Published: April 2010

An electron microscopical study was made on the lobule boundary cells. They were found to show characteristic ultrastructures of a typical steroid‐producing cell. Changes in these cells were divided into five stages according to the development within the lobules. The possible significance of the changes and their correlation with the degree of steroid production at different stages are discussed.
Ultrastructure of the Testicular Interstitial Tissue of the Hagfish Eptatretus stouti
Authors: Tsuneki Kazuhiko , Gorbman Aubrey
Published: April 2010

Ultrastructure of the somatic components of the testis of the Pacific hagfish was studied. Interstitial cells, equivalent to Leydig cells of higher vertebrates, containing smooth‐surfaced endoplasmic reticulum and mitochondria with tubular cristae were found in the interstitial tissue, as well as leucocytes, fibroblasts and other cells of unknown role. Two kinds of somatic cells were observed in the testicular follicles: Sertoli cells and “stellate cells”. The significance of interstitial cells was discussed in relation to possible involvement in steroidogenesis.
Blood and Spleen Response to Isolation and Cold Stress in Little Brown Bats, Myotis lucifugus
Authors: Martin Kathryn H. , Stehn Robert A.
Published: April 2010

Female bats were housed singly or in groups and maintained at 5° or 23 °C. Red blood cell life spans were determined utilizing the disappearance of labeled sodium chromate (Cr51). Red cell counts, hematocrits, reticulocyte percentages and diameters, white cell differentials, and spleen histology were determined for bats subjected to three weeks of stress treatment. Isolated animals (warm and cold) had significantly lower hematocrits and red cell counts and significantly higher reticulocyte diameters and percentages than grouped bats. Random destruction of erythrocytes was initially higher in isolated bats. In cold and isolated animals the white pulp of the spleen was most reduced in quantity and in proliferative activity. Red pulp became highly engorged with erythrocytes and showed a hypertrophy of reticuloendothelial elements. Higher rates of random destruction are closely correlated with increased splenic erythrophagocytosis. Gold or isolation imposed separately are mild stress factors in little brown bats, while a severe stress response occurs when the two stressors are imposed simultaneously.
The Distribution of Sudoriferous Glands in the Hairy Skin of Reindeer (Rangifer tarandus L.)
Authors: Källquist Lollo , Mossing Torgny
Published: April 2010

Skin samples were taken from forest reindeer (Rangifer tarandus L.) in order to study the distribution of apocrine tubular glands. Glands with well‐developed secretory epithelium were restricted to certain areas of the body, namely the foreleg pit, a narrow strip on the belly, the groin and on the legs. Well‐developed glands were also found in the oral angle and in the rump patch. The greatest amount was found in the ventral interdigital skin of both fore and hindfeet. In other parts of the body could only the excretory duct and a thin walled extension but no developed secretory epithelium be seen.
Functional Anatomy of the Alimentary Canal in the Fruit Bat, Eidolon helvum, and the Insect Bat, Tadarida nigeriae
Authors: Okon Eyo E.
Published: April 2010

The gastrointestinal anatomy of the frugivorous bat, Eidolon helvum was compared with that of the insectivorous bat, Tadarida nigeriae. Both show modifications related to differences in their food habits as well as other anatomical peculiarities. The gastroesophageal junction in Eidolon helvum possesses a sphincter‐like protrusion. The posterior 10 mm of the esophagus in the same bat has well developed gastric glands, while the stomach is unexpectedly very rich in zymogenic and parietal cells. The intestine in this species is about 170 cm long; the posterior 30 cm of this is of colonic histology, though showing no external morphological difference from the small intestine. The anterior duodenum of Tadarida nigeriae has an external protuberance consisting of mucus secreting glands. The intestine of this bat has no colon, but a very short rectum of goblet cells is present.
The Maturation of the Ovary in Wild Rabbits, Oryctolagus cuniculus, in South Sweden
Authors: Andersson Mats , Meurling Patrick
Published: April 2010

In the ovaries of wild yearling rabbits the histologic changes occurring between September and March were determined and related to age and season. It was found that a considerable part of the ovarian development is characterized by the growth of follicles which soon become atretic and form interstitial gland tissue. The ovarian development up to a “sub‐ovulatory” stage may be completed in the autumn in rabbits born early in the season, and later in those born late, so that by mid‐winter they are all in this stage. No ovulation was found in rabbits in the early stages of development, and it is suggested that the presence of interstitial tissue is essential for full reproductive capacity.
Effects of Hypophysectomy and Prolactin Replacement on Eel Kidney Structure During Adaptation to Sea Water
Authors: Olivereau Madeleine , Olivereau Jacqueline
Published: April 2010

After 20 to 50 days in sea water (SW), regressive changes of the kidney occur at the same rate in intact and hypophysectomized eels (Anguilla anguilla). In SW, ovine prolactin (oPRL) increases plasma electrolytes and restores a fresh water (FW) kidney structure; cell height and nuclear area increase in main segments of the nephron: first (P1) and second proximal (P2), distal (D) and initial collecting (C) tubules. A differentiation of new tubules also occurs. This effect is less intense after hypophysectomy and greater in FW. A dose of 10 μg/g body weight/day for 10 days in SW produces some harmful renal effects, barely detected at 6 μg/g/day. The kidney plays a minor role in osmotic adjustment in SW when PRL secretion is reduced (intact eels) or suppressed (hypophysectomized); PRL treatment reverses effects of SW adaptation. An inhibition of gill sodium extrusion may explain the high blood sodium level; however, kidney histological changes suggest a renal participation, perhaps through reduced water permeability as in Platichthys.
Studies on the Fibrous Components of the Test of Ciona intestinalis Linnæus. I. Cellulose‐like Polysaccharide
Authors: De Leo Giacomo , Patricolo Eleonora , Lunetta Giuseppina D'Ancona
Published: April 2010

Chemical, histochemical and electron microscopic studies on the fibrous polysaccharide component of the test of Ciona intestinalis L. were made. The results showed cellulose‐like fibres to be present in the cuticle layer and in the ground substance. Bundles of fibres varying in diameter from 80 to 600 nm interweave to form a conspicuous network. The bundle appears to be formed of flat fibres, 10–13 nm in width, while the fibre is composed of fibrils 3.5–5 nm; the rectangular cross section of fibres can be supposed. The probable rôle of this polysaccharide is discussed.
The Ultrastructure of the Indirect Flight Muscles of the Monarch Butterfly, Danaus plexippus (L.) with Implications for Fuel Utilization
Authors: Wensler Rita J.
Published: April 2010

The fine structure of the dorsal longitudinal flight muscle of the monarch butterfly, Danaus plexippus (L.), is described. The high actin: myosin filament ratio in this fast muscle is likely related to extensive actin‐myosin filament interaction which must occur when tension is increased and maintained by repeated nervous stimulation as demonstrated by Kammer (1967) during the long downstroke of the wingbeat cycle.

Glycogen particles are present in the granular fraction of the interfibrillar sacroplasm and among the myofilaments of the flight muscle of young butterflies. The distribution of the granules appears to be related to spatial forces within the muscle fibril for in resting butterflies the intermyofilament particles are generally located in rows parallel to the myofilaments, while they are in transverse bands in the H and I zones of animals fixed immediately after flight. Since the glycogen particles were not depleted during flight, this redistribution does not appear to be related to glycogen metabolism.

Glycogen in the flight muscle was depleted during eight days of adulthood in butterflies fed on honey solutions, but lipid reserves increased in the same period.
Compound Eyes of Some Deep‐Sea and Fiord Mysid Crustaceans
Authors: Elofsson Rolf , Hallberg Eric
Published: April 2010

The compound eyes of the deep‐sea mysid Boreomysis scyphops and the two mysid species Amblyops abbreviata and Pseudomma affine, which are indigenous to deep fiords in Norway, have been investigated. The eye stalks are greatly transformed, but contain hypertrophied retinas. The ommatidia of all three species lack a dioptric apparatus, possessing only retinular cells, which are arranged in a cylinder‐like fashion. Folds from the retinular cells project into the “cylinder” and are covered with microvilli. The arrangement is explained functionally by an increase in the photopigment‐bearing surface as an adaptation to low‐light intensities. The orderly arrangement of microvilli in most arthropod compound eyes has been lost, and the arrangement is thus multidirectional in these mysids. With the photopigment dipoles arranged along the microvillar axis, the disorderly arrangement of microvilli signifies a more efficient capture of non‐polarized light. It is concluded that the mysid compound eyes show adaptations to low‐light intensities probably acquired during the species' evolutionary descent into deep‐sea habitats. Amblyops abbreviata and Pseudomma affine, belonging to genera with entirely transformed eyes and with an ultrastructure less “normal” than that of Boreomysis scyphops are believed to be earlier descendants into the deep‐sea habitats than the latter species, which belongs to a genus in which most of the species have well‐developed eyes.
Ultrastructure of the Stylet Protractor Muscle in Gyratrix hermaphroditus (Turbellaria, Rhabdocoela)
Authors: Reuter Maria
Published: April 2010

The subsarcolemmal cisternae of the sarcoplasmic reticulum form peripheral couplings with the sarcolemma. The junctional gap is crossed by periodic densities called junctional processes. Desmosomes provide mechanical coupling between the myofibres. Hemidesmosomes connect the myofibre with a well developed connective tissue sheath.
On the Organisation of the Sarcotubular Systems in the Caudal Muscle Cells of Larvaceans (Tunicata)
Authors: Bone Quentin , Flood P. R. , Mackie G. O. , Singla C. L.
Published: April 2010

The structure of the sarcotubular systems of the caudal muscle cells is described in various larvaceans. In Oikopleura there is both a transverse tubular system and a sarcoplasmic reticulum; there are internal couplings between the two and also sarcolemmal couplings. In Fritillaria (and probably also in Kowalevskaia), a transverse tubular system is lacking, and there are only sarcolemmal couplings with the sarcoplasmic reticulum, which is related to the mitochondria as well as to the myofilaments. The significance of these differences is discussed, and it is concluded that the arrangement of the sarcotubular systems is related to muscle fibre thickness; within the Tunicata, these systems do not indicate phylogenetic relationships.
The Organ of Bellonci in Ostracodes: An Ultrastructural Study of the Rod‐shaped, or Frontal, Organ
Authors: Andersson Anders
Published: April 2010

Ultrastructural observations of the rod‐shaped organ in Cypridina norvegica and Paraconchoecia elegans indicate homology with the organ of Bellonci of other crustaceans. In C. norvegica the organ is situated close to the ventral cup of the nauplius eye. Distally in the organ, several ciliary ramifications of the sensory neurons protrude into internal cavities formed by bordering cells. Six dendrites, with cell bodies within and in front of the brain, form the proximally bifurcated nerve, which enters the protocerebrum in the region of the medullae terminales. In this species the organ represents the deep receptor of the organ of Bellonci complex. In P. elegans the external part of the organ is situated between the proximal parts of the antennulae. Four dendrites in two groups emerge from the protocerebrum. Distally, they form branching cilia that are in close contact which the cuticle of the organ, thus forming a receptor similar to the superficial receptor of the organ of Bellonci complex of other crustaceans. It is suggested that the terms frontal organ and rod‐shaped organ be abandoned in favour of the term organ of Bellonci.
Blood Cell Ultrastructure of the Ascidian Botryllus schlosseri.
Authors: Milanesi Carla , Burighel Paolo
Published: April 2010

In the blood of B. schlosseri these cell types are constantly present: hemoblasts, granulocytes, macrophages, morula cells, nephrocytes and pigmented cells. All blood cells seem to have a common origin from the hemoblast, which is an undifferentiated cell with large nucleus, prominent nucleolus and cytoplasm filled with ribosomes. At least two kinds of granulocyte (microgranular and macro‐granular amoebocyte) are recognizable on the basis of granule size. Furthermore, the microgranular amoebocyte contains small vesicles, glycogen and peripheral bundles of microfilaments. The macrogranular amoebocyte displays a well developed RER formed by elongated cisterns that contain a finely granular material and swell to form large sac‐like structures. Specialized amoebocytes (macrophages) can phagocytize cell fragments and entire cells, thus forming large necrotic masses. The morula cell is characterized by large vacuoles in which are strongly electron dense masses that contain iron, as revealed by X‐ray microanalysis. Both young and mature morula cells are described and the probable formation of the masses from the Golgi complex is suggested. The nephrocyte (purinic cell) shows very few giant vacuoles containing numerous granules, mostly electron lucent and often of geometric form, that are presumably the same as the refringent granules visible in vivo.
Etude anatomique et histologique du squelette axial de Eigenmannia virescens (Rhamphichthyidae, Gymnotoidei)
Authors: Meunier François Jean , Kirschbaum Frank
Published: April 2010

The number of vertebrae varies from 77 up to 81, of which 16 to 22 belong to the caudal region. The last vertebra is followed by a rodlike bone and this, in turn, by a cylindric piece of cartilage measuring 2–3 mm in length. The rodlike tail bone is first seen when the fish reaches a length of 40 to 45 mm; its development seems to be induced by the caudal cartilage just referred to. The latter element is initially in contact with the posterior extremity of the notochord; as it grows backwards, however, its anterior part gradually becomes destroyed by chondroclasts. The caudal cartilage is tentatively interpreted as an opisthure and the rodlike tail bone as a neomorph.
The Vascularization of the Anuran Brain: The Choroid Plexus of the Fourth Ventricle
Authors: Lametschwandtner Alois , Albrecht Ursula , Adam Hans
Published: April 2010

The angioarchitecture of the choroid plexus of the fourth ventricle of the toad, Bufo bufo (L.) has been studied by scanning electron microscopy of vascular corrosion casts. The results agree with the findings of Gaupp (1898) and show a wholly venous supply of the plexus. The drainage is exerted via venae choroideales rhombencephali. We discern three distinct but continuous zones. They are from dorsal to ventral a) the vascular reticulum within the tela choroidea, b) transverse orientated vascular nets within the ventricular folds (10–15) of the tela choroidea and c) vascular loops within the choroidal villi. — In the present paper we also discuss the method we used. Its advantages are powerful representation, striking information concerning the microvascular patterns and some hints to the statics caused by them, the possibility of tracing arteries through capillaries to veins over a long distance and the demonstration of vascular routes between important functional regions. Evasation, caused by to high injection pressures, no evidence for the direction of blood flow, no fully convincing surface patterns of the casts which clearly indicate arteries or veins (arterioles or venoles) and no reliable reflection of the physiological state of the animal are shortcomings, which demand a careful interpretation of the results.
A Pilot Study on the Long Term Anatomical Effects of Ectomy of the Urophysial System in the Teleost Fish Rutilus rutilus
Authors: Fridberg Gunnar , Ekengren Bo
Published: April 2010

Roaches 16 months old survive the removal of the urophysial system for more than 11 months. The absence of the system for this period had some very significant anatomical effects. The growth of the fish as well as the viscera was strongly retarded whereas the kidneys, the mesonephros, were enlarged. If the caudal peduncle was cut away from the 6—7 vertebrae numbered from the urostyle a new system regenerated and the fish showed normal growth and development. If the site of pedunclectomy was at vertebra 12 numbered from the tailfin or anterior to it no regeneration of the system took place. The urophysial hormones seem to play an important role as synergetic factors for normal growth and development of the fish. Observations indicate their possible interaction with the preoptico‐hypophysial system in osmoregulation.
Fine Structure of the Developing Scale in the Cichlid Hemichromis bimaculatus (Pisces, Teleostei, Perciformes)
Authors: Sire Jean‐Yves , Géraudie Jacqueline
Published: April 2010

The study of the formation and structure of the early teleost scale and its associated cells has been carried out on Hemichromis bimaculatus fry using in toto staining with alizarin and transmission electron microscopy techniques. Results of the study show very rapid scale formation in Hemichromis. The papilla of the scale differentiates a little in advance of the bone scale formation. No epidermal cells are involved in the constitution of the scale pocket made up of scleroblasts. In Hemichromis, as in other teleost scales, the osseous layer is the first one to be secreted by, presumably, only the scleroblasts. Then the scleroblasts specialize in their functions. Superficial ones are involved in the formation of osseous circuli; marginal scleroblasts are responsible for growth in diameter of the scale; while deep scleroblasts allow the scales to thicken owing to the progressive addition of collagen fibrils organized in a “plywood‐like” structure which constitutes the fibrillary plate of the scale. Mineralization occurs very rapidly within the osseous layer in the form of hydroxyapatite‐like crystal deposits. The fibrillary plate is not yet mineralized in Hemichromis at the stages studied here, but presumably is later. Results obtained in Hemichromis are discussed against similar data available in the literature on teleost scale formation.
Changes in Calcium Reserves in Breeding Lesser Snow Geese (Chen caerulescens caerulescens)
Authors: Campbell R.R. , Leatherland J. F.
Published: April 2010

Calcium and fat reserves of the femur medullary bone were examined in sexually mature lesser snow geese (Chen caerulescens caerulescens) collected during the 1974–1975 season. In females, femur calcium and fat levels increased by 80 and 30%, respectively, during the spring migration, much of the increase taking place while the birds staged in southwestern Manitoba and North Dakota prior to their departure for the breeding area. In males. femur calcium levels showed no seasonal change but femur fat increased in a manner similar to that found in the females, although the increase was not as great (17%). In the females, femur fat content fell by 40% during egg‐laying whereas in males a decrease in femur lipid was not evident until incubation was well underway. Femur calcium levels in females declined during egg production and early incubation, showing a 56% decrease over spring migratory levels, indicating that dietary calcium intake was limited during the nesting period. However, the low femur calcium levels in birds collected during the spring were not significantly different from those of wintering birds, suggesting that no calcium deficiencies were apparent. Plasma calcium levels in males remained relatively constant throughout the year, although there was some elevation in May. Plasma calcium levels in the females increased almost threefold during egg laying and returned to pre‐laying levels during incubation. Medullary bone was evident only in reproducing females and appeared during spring migration, concomitant with increased femur weight, fat and calcium content. Medullary bone degradation commenced during the first week of incubation and no medullary bone was in evidence by molt. Calcium reserves of medullary bone accounted for only 17.2% of the calcium required for eggshell production, suggesting that. at least during the laying period, the female must depend on some exogenous source, perhaps from grit or brackish water.
Spermiogenesis in Anaspides tasmaniae (Thomson) (Crustacea, Malacostraca, Syncarida)
Authors: Jespersen Åse
Published: April 2010

Spermiogenesis of the syncarid Anaspides tasmaniae (subclass Eumalacostraca) was investigated by transmission electron microscopy. The spermatozoan of Anaspides is an ovoid cell with an acrosome covering the anterior pole and a lobulated nucleus and mitochondria occupying the rest of the cell. A long subacrosomal filament bypasses the nucleus and forms a spiral that supports a thin extension of the posterior cytoplasm, giving the spermatozoan a bell‐shaped appearance. No flagellum is present at any stage. The immobile spermatozoans are embedded in a hard capsule, secreted by the cells of the wall of the vas deferens.
The Subcommissural Organ‐Liquor Fibre Complex: the Binding of Catecholamines to the Liquor Fibre in Frogs of the Rana esculenta Complex
Authors: Diederen J.H.B: , Vullings H.G.B. , Rombout J.H.W.M. , de Gunst‐Schoonderwoerd A.T.M.
Published: April 2010

Tritiated catecholamines were administered to European green frogs by means of injection into the brain cavity. Their fate within the brain was followed autoradiographically. Especially after injection of 3H‐noradrenaline, considerable amounts of radioactive material were found closely associated with the liquor fibre (Reissner's fibre; LF) which is produced by the subcommissural organ. In frogs which survived 3 or 12 hours after injection, the association of radioactive material with the LF appeared to be restricted mainly to the cerebral ventricles, whereas in frogs which survived 24 hours, the radioactivity associated with the LF was most abundant well into the central canal of the spinal cord. The results indicate that the LF is able to pick up, from the cerebrospinal fluid, and bind certain catecholaminergic substances (especially noradrenaline, but not dopamine) and/or their metabolites by rather strong binding forces. The attached material is then transported by the LF into the central canal of the spinal cord, with its practically stagnant fluid content. These results confirm data known from the literature. which are indicative of the LF being involved in regulation of the composition of the fluid within the central canal, e.g. by providing this canal with catecholaminergic substances and/or by removing them from it.
Immunohistochemical Identification of Cell Types in the Pars Distalis of Harp Seals, Phoca groenlandica
Authors: Leatherland J.F. , Ronald K.
Published: April 2010

The distribution of pars distalis mammotropic, somatotropic, luteotropic, folliculotropic, thyrotropic and corticotropic cells was examined in neonate, juvenile and adult harp seals (Phoca groenlandica) by means of immunohistochemistry, employing antisera to hormones of human or rat origin. All the cell types were evident in one day‐old animals, except for immunoreactive folliculotropic cells which were first apparent in five day‐old animals. Mammotropic cells were small and relatively inactive in neonatal animals compared with the juvenile and adults. Somatotrops increased in apparent activity between one and five days postpartum, were most active in the juveniles, and less so in the adults. The corticotrops, found predominantly in the anterior regions of the pars distalis, appeared to increase in number and activity in adult seals. The gonadotrops increased in numbers as the animals aged, but the cells tended to be smaller in the juvenile and adult animals. The thyrotrops were small cells found only in the central regions of the pars distalis. The distribution of immunostained cell types is compared with cell type characterization of the same pituitaries based on light and electron microscopic evidence alone.
The Glandular Tissue in the Testis of Salamandra salamandra (L.) (Amphibia, Urodela)
Authors: Bergmann Martin , Schindelmeiser Jochen , Greven Hartmut
Published: April 2010

The glandular tissue in the testis of the urodele Salamandra salamandra was studied by electron microscopy during different developmental stages. After spermiation, steroid hormone (SH)‐secreting cells, which surround seminiferous units (lobules) of the mature part of the testis, proliferate, whereas fibrocytes of the same lobule boundary transform into smooth muscle cells, which in part become closely associated with the epithelium of ductuli efferentes. Sertoli cells within the lobules appear not to be involved in SH‐secretion; they phagocytize spermatozoa which have not been discharged. In the residual stage SH‐secreting cells, as well as Sertoli cells, are degenerated. The tissue is composed of undifferentiated fibrocytic cells, probably derived from smooth muscle cells and/or SH‐secreting cells, of solid cell cords representing the formerly open ductuli efferentes and of primordial germ cells ensheathed by follicle cells. There are indications that smooth muscle cells are involved in phagocytosis when glandular tissue undergoes regression.
Immunocytochemical Investigations of the Infundibular Organ in Amphioxus (Branchiostoma lanceolatum; Cephalochordata)
Authors: Sterba Günther , Fredriksson Gunnar , Olsson Ragnar
Published: April 2010

Reissner's fibre (RF) is an extraordinary ancient feature of the chordate central nervous system. In vertebrates the RF material is released by the cells of the subcommissural organ (SCO) situated in the roof of the brain. In cephalochordates the RF forming apparatus is the infundibular organ (IFO), a structure in the floor of the brain vesicle. Both the SCO and the IFO are areas of specialized secretory ependymal cells. Recently the SCO‐secretion of many vertebrate species has been studied immunocytochemically by use of different antisera against RF‐material from cows. The present investigation with the PAP‐technique showed that these antisera give a positive immunocytochemical reaction with the secretion of the IFO of amphioxus. The results indicate molecular similarities of compounds present in both the SCO‐secretion and the IFO‐secretion. The conception that the SCO and the IFO are descendants from a single large glandular area in the brain vesicle of an ancient chordate ancestor is emphasized by these findings
Cell Types in the Mesencephalic Trigeminal Nucleus of Mauremys caspica
Authors: Fernández Elvira Fernández , Doel Rosa María Paz
Published: April 2010

A classification of the neurons of the mesencephalic trigeminal nucleus (MTN) has been carried out in the adult turtle Mauremys caspica on the basis of cell size and the shape and arrangement of the Nissl granules, following Sheinin's (1930) criteria for the dog MTN. The authors describe the nucleus as being divided in two cell populations with different neuronal composition and tectal location and probably distinct embryonic sites of origin. The morphological variation observed in the trigeminal neurons might be an expression of functional specialization.
Developmental Changes in the Epidermal Surface Cells of Salamander Larva
Authors: Lewinson Dina , Rosenberg Mira , Warburg M.R.
Published: April 2010

Epidermal surface cells were studied ultrastructurally and histochemically at various larval stages in Salamandra salamandra. The most outstanding cellular structures undergoing changes were found to be secretory vesicles, mitochondria and tonofilaments. The highest density of secretory vesicles was noticed immediately after birth, declining in number at later stages and almost disappearing at metamorphosis. The mitochondria, whose appearance at early stages indicates a high metabolic activity, hypertrophy and degenerate close to metamorphosis. Simultaneously, there is an increase in the cellular tonofilaments' density reaching its climax with keratinization.
Localization of Two Brominated Metabolites, Aerothionin and Homoaerothionin, in Spherulous Cells of the Marine Sponge Aplysina fistularis (=Verongia thiona)
Authors: Thompson Janice E. , Barrow Kevin D. , Faulkner D. John
Published: April 2010

Energy dispersive X‐ray microanalysis was used to localize the two brominated natural products (aerothinonin and homoaerothionin) in the tissues of a marine demosponge, Aplysina fistularis. Virtually all of these compounds were localized within the spherules of the spherulous cells in the mesohyl. This is the first localization of any secondary metabolite at the cellular or sub‐cellular level in any marine invertebrate. In Aplysina fistularis, as in other species of the same genus studied by Vacelet, the spherulous cells are concentrated just beneath the exopinacoderm and just beneath the endopinacoderm of the excurrent canals. Moreover, there is electron microscopic evidence for degeneration of some spherulous cells throughout the mesohyl. Presumably, this degeneration can release some aerothionin and homoaerothionin, which are known to have antibiotic properties. After release from the spherulous cells, these brominated natural products could function (1) within the mesohyl to exclude some types of bacteria or to aggregate ingested bacteria and/or (2) within the boundary layer of the surrounding seawater for defense or offense, as considered in the discussion section.
The Parapineal Organ of Teleosts
Authors: Borg Bertil , Ekström Peter , van Veen Theo
Published: April 2010

A parapineal organ was found to be present in 21 teleost fishes belonging to 20 different families, but was absent in poecilids and cyprinodontids. The parapineal organ was situated on the left side of the brain and sent a nerve tract to the left habenular nucleus, except in Gadus, where a “parapineal organ” appeared to send a nerve tract into the pineal stalk. The parapineal organ of adult Gasterosteus consisted of glial elements and parapinealocytes. The latter were small neurons which sent off the unmyelinated axons that formed the parapineal tract. A single photoreceptor cell was found in a stickleback parapineal organ.
The Formation of Otoliths in the Frog Rana esculenta. Scanning Electron Microscopic and X‐Ray Diffraction Studies
Authors: Marmo Francesco , Balsamo Giuseppe , Franco Enrico
Published: April 2010

Two crystal forms of calcium carbonate were observed: calcite (utricle) and aragonite (saccule, lagena, endolymphatic sac). The first step in otolith formation is the appearance of organic structures in the macula. The subsequent step is characterized by fast growing primitive crystals with a prismatic habitus that successively transform into adult or mature crystals. With the metamorphosis, the aragonite crystals of the endolymphatic organ show clear signs of erosion that can be related to a process of CaCO3 mobilization from such deposits.
Spermiogenesis in a Pycnogonid Achelia echinata Hodge
Authors: El‐Hawawi A.S.N. , King P.E.
Published: April 2010

Spermiogenesis and structure of the mature sperm are described in Achelia echinata Hodge. The sperm differ from previously described types and perhaps represent an unspecialised type.
The Lympho‐Hemopoietic Organs of the Anadromous Sea Lamprey, Petromyzon marinus. A Comparative Study throughout its Life Span
Authors: Ardavin C.F. , Gomariz R.P. , Barrutia M.G. , Fonfria J. , Zapata A.
Published: April 2010

We have analyzed morphological changes affecting the lympho‐hemopoietic organs of the anadromous sea lamprey, Petromyzon marinus throughout its life span. For this analysis, ammocoetes (2–4 years), premetamorphosing lampreys (nearly 5 years), metamorphosing lampreys, macrophtalmia stages (young adults) and parasitic adults (nearly 7 years) were used. The principal lympho‐hemopoietic organs in the ammocoete are typhlosole, larval opisthonephros and nephros‐associated adipose tissue. After metamorphosis, these organs degenerate, and their lympho‐hemopoietic tissue is replaced by dense connective tissue. The supraneural body and to a lesser degree, the definitive opisthonephros, are the main blood‐forming organs in adult lampreys. During larval life, lympho‐hemopoietic cells appear in the branchial area, associated with pharyngeal epithelium. These loci are not morphologically homologous to the thymus gland of jawed vertebrates. These results are discussed, with special emphasis on the importance of cell microenvironments in eluciding changes in different blood‐forming loci throughout the life cycle and their significance for the lamprey's immune capacity.
Ultrastructural Studies on Gametogenesis of the Prawn Palaemon serratus (Pennant). II. Spermiogenesis
Authors: Papathanassiou E. , King P. E.
Published: April 2010

Spermiogenesis in Palaemon serratus is described. The mature sperm has an atypical form and is highly modified. In early stages of spermiogenesis mitochondria, golgi complexes, stacks of annulate lamellae and endoplasmic reticulum are present but disappear later in development. Two modified mitochondria are present in the mature sperm. This latter consists of a cup‐shaped nucleus, a cross‐striated “spike”, has a centriole and lacks an acrosome. The nucleus contains membrane‐bounded vesicles which arise by pinocytosis. The “spike” may be a flexible posterior organ which suggests a mode of fertilization requiring limited mobility.
The Fine Structure of the Stalk of the Pentacrinoid Larva of a Feather Star, Comanthus japonica (Echinodermata: Crinoidea)
Authors: Grimmer John C. , Holland Nicholas D. , Kubota Hiroshi
Published: April 2010

The stalk of the pentacrinoid larva of a feather star (Comanthus japonica) is described for the first time by transmission electron microscopy. One end of the stalk bears the calyx and the other end is cemented to the substrate by attachment cement consisting of a meshwork of 5 nm filaments. The stalk is supported by a scries of skeletal ossicles pierced by a central canal: short intercolumnal ligaments connect adjacent skeletal ossicles and central through‐going ligaments run the length of the central canal. At the end of the stalk nearest the calyx, the chambered organ and the closely associated axial organ are histologically similar to those of adult crinoids. Presumed neurosecretory neurons are associated with the intercolumnal ligaments, and the following kinds of nerves run down the central canal: (1) a large stalk nerve in each of the five interradii; (2) smaller coelomic nerves in each of the five radii in association with the epithelium of tubular aboral extensions of the chambered organ; (3) a very small nerve associated with the aboral extension of the axial organ in the stalk axis. This axial organ extension is surrounded by a haemal channel. Because of the small size of the stalk, none of the nerves or the haemal channel were described in previous light microscopic studies. The discussion gives special attention to the controversial motility of the pentacrinoid stalk.
Coelomocytes of Nephtys coeca (Annelida, Polychaeta)
Authors: Mattisson Artur
Published: April 2010

Coelomocytes of Nephtys coeca were studied by transmission electron microscopy. The majority of the coelomocytes were found to be structurally identical with the muscle cells of the body wall. Animals kept under unfavourable conditions tended to have an increased number of coelomocytes and a decreased thickness of the body wall. The muscular coelomocytes, probably released from the body wall, showed various degrees of decomposition, indicating a process of autophagy.
On the Caudal Heart of Myxine (Myxinoidea:Cyclostomata)
Authors: Satchell Geoffrey H.
Published: April 2010

The anatomy of the caudal heart of Myxine glutinosa is reviewed and a hypothesis of its mode of action is outlined. It is a double‐action force pump in which each stroke produces two results, the filling of one chamber and the emptying of the other. This hypothesis is supported by records of blood pressures (a) in the caudal vein, which show elevations of pressure as the left and right chambers are alternately emptied, and (b) in the subcutaneous sinuses, which show alternating reductions of pressure corresponding to the aspiration phases of the left and right sides. The caudal heart shows a diminishing sequence of bursts of activity following each bout of swimming; blood continues to flow slowly through the resting caudal heart. The conclusion is drawn that it is an auxillary venous pump, and it is compared with the lymph heart in the tail of teleost fish.
Observations on the Extracellular Spaces and Intercellular Junctions in Diphyllobothrium dendriticum (Cestoda)
Authors: Lindroos Paula
Published: April 2010

Extracellular spaces and intercellular junctions were studied in adult Diphyllobothrium dendriticum after lanthanum nitrate infiltration. The parasitic tapeworms absorb nutrients across the whole body surface, the syncytial tegument. The results indicate that the distribution of nutrients can occur both in the extracellular stroma and in the intracellular compartment, through intercellular junctions of the gap junction‐type. The fibrous basal lamina of the tegument forms a large extracellular compartment communicating through narrow interstices in the subtegument with extracellular lacunae in the parenchyma. Intercellular junctions of the gap junction‐type frequently occur between the tegument cell bodies, as well as between tegument and parenchymal cells. According to the function of these cells in nutrient uptake and storage, metabolic coupling seemed the most likely mission for these junctions. Thus it can be concluded that the extracellular spaces and the intercellular junctions create the possibilities for an efficient distribution of nutrients in this tapeworm.
Dynamics of Oogenesis in a Lower Vertebrate, the Toad Bufo bufo
Authors: Jørgensen C. Barker
Published: April 2010

The patterns of production and growth of oocytes were studied in female toads brought into the laboratory after hibernation and kept at 20°C. The oogenic state of the ovaries was determined from the number and size frequency distribution of the oocytes, and change in oogenic state was followed by comparing ovarian biopsies with the ovaries at autopsy one month later. New oocytes grew within one month to sizes up to 0.16 mm or more in diameter, and were integrated in the existing pool of small oocytes. Production of new oocytes continued for more than one month, perhaps 2–3 months, to increase the pool of oocytes by about 50%. An episode of oogenesis sensu stricto is followed by a resting period, probably lasting for about 1–2 years. Oogenesis was not coordinated with ovulation or recruitment of oocytes to vitellogenic growth and it occurred also in the ovaries of sexually immature toads. Exogenous gonadotropin (hCG) and/or fasting for one month of toads in a good nutritional condition did not affect oogenesis, but no oogenic episodes were observed in the ovaries of starving toads that were depleted of energy reserves. It is concluded that oogenesis and growth of oocytes constitute a dynamic system that is only inadequately described by the widely accepted linear, sequential model of production of eggs in amphibians and teleosts.
The Sense Organs and Ventral Ganglion of Sagitta (Chaetognatha)
Authors: Bone Quentin , Pulsford Ann
Published: April 2010

This paper describes some features of the chaetognath nervous system from ultrastructural observations and observations on material stained with specific techniques for nervous tissue, and from records of the activity of the locomotor muscles and ventral ganglion. Sensory cells grouped on the ventral surface of the head bear ciliary processes (some with multiple tubules), and are probably in connexion with the central nervous system by their own axons, unlike the sensory cells of the hair fan vibration receptors of head and body. The ventral ganglion is motor to the locomotor muscles of the body, and controls the rhythmic locomotor activity of the animal. Electrical events associated with contraction of these muscles are compound non‐overshooting spike‐like potentials. The ventral ganglion contains several large nerve fibres constant in position and connexions in different individuals. Some of these arise from cells in the ganglia of the head, and pass to the ventral ganglion, others from cells within the ventral ganglion, and probably supply the ciliary hair fan receptors of the body, whilst the motor axons issuing from the ventral ganglion are smaller in diameter. The ganglion is arranged on a ladder‐like plan, and axons of the lateral cell bodies cross the central neuropil transversely before they contribute to the longitudinal tracts or pass out in the radial nerves. Synapses in the neuropil contain 30–40 nm electron lucent vesicles; the transmitter is unknown, but is unlikely to be either acetylcholine or l‐glutamate. Occasional larger electron dense vesicles up to 70 nm in diameter are also found within nerve fibres of the neuropil. It is concluded that the arrangement of the peripheral nervous system is unlike that of several groups which have been suggested as related to chaetognaths.