bluuebunny/crossref_metadata_2025 huggingface dataset:
Cochlear hair‐cell populations and limits of resolution of hearing in two vespertilionid bats, Nyctalus noctula and Eptesicus serotinus
Authors: Burda Hynek , Úlehlová Libuše
Published: February 2005

A comparison of the population of cochlear hair cells with known hearing resolution capabilities in two species of bats (Nyctalus noctula and Eptesicus serotinus of the family Vespertilionidae) has revealed a close correlation between morphological and functional parameters. Data on number and densities of hair cells in the examined bat species are presented. Even though the species are of a comparable body size, N. noctula has a longer basilar membrane, a higher density, and hence also a higher total number of hair cells than E. serotinus. This is in good agreement with hearing resolution capabilities, which are better in N. noctula than in E. serotinus. These findings have implications on differences in feeding ecology and hunting strategies between these species.
An ultrastructural study of the melanophages in the cerebrospinal fluid of the tadpoles of Xenopus
Authors: Kordylewski Leszek
Published: February 2005

Melanin deposits in the brain ventricles of Xenopus tadpoles were studied with light and electron microscopy (TEM and SEM). They appeared to be aggregations of melanophages which accumulated free pigment granules excreted by ependymal cells into the cerebrospinal fluid. Whereas the meningeal melanophores contained oval melanosomes of various sizes, the melanosomes in the scavenger cells were all spherical, large (0.6–1.1 μm) and fairly uniform in size. Moreover, they were arranged in spherical groups which were never seen in the cytoplasm of the melanophores. The melanosomes within the cells were identical to the free melanosomes found in the cerebrospinal fluid and those which occurred within the ependymal cells in the young larva, suggesting a common origin from the egg cytoplasm.

The number of the melanosomes in the melanophages increased with age. Fine cytoplasmic projections were involved in catching and engulfing the melanosomes. Some other features of the cytoplasm, e.g., large deposits of cell detritus, also indicated that the cells were macrophages. In the later stages, (48, 49) no projections were observed, but the cells were totally filled with melanosomes.
Ultrastructural aspects of dental tissues and their behavior in xenoplastic association (lizard quail)
Authors: Lemus D. , Fuenzalida M. , Illanes J. , De La Vega Y. Paz
Published: February 2005

Ultrastructural characteristics of tooth buds of the polyphyodont adult lizards Liolaemus tenuis and Liolaemus gravenhorsti have been elucidated. Xenoplastic combinations of lizard whole tooth buds and neural crest cells from embryos of the quail Coturnix coturnix japónica have been cultured in vitro. Mesenchymal cells (preodontoblasts) of lizard teeth early develop filopodia that contact the basal lamina. Fragments of quail neural crest isolated by dissection were recombined with isolated lizard tooth buds and cultured for 84 hours in dishes kept in an incubator at 37.8°C in air. Some identifiable quail cells in these recombinants developed a cytoplasmic extension like that of an odontoblastic process. These results suggest that lizard tooth rudiments already determined for tooth development produce some non‐species specific transmissible constituents which are capable of inducing quail cranial neural crest cells to express certain dental characteristics (odontoblastogenesis) not expressed in their normal development in vivo.
Permeable sites in the firefly lantern tracheal system: Use of osmium tetroxide vapor as a tracer
Authors: Ghiradella H.
Published: February 2005

Flashing fireflies were permitted to breathe osmium tetroxide vapor, after which the lanterns were removed and the sites of absorption of the osmium into the tissues were detected in two ways: (1) by sonication to remove soft tissues, that is, those that had not been fixed by the osmium gas, and (2) by intensification with thiocarbohydrazide and silver nitrate, in a modification of the osmium–thiocarbohydrazide–osmium (OTO) stain technique. The results of both procedures indicate that the gas first enters into the tissues at the level of the tracheoles. These findings may be interpreted as underscoring the importance of the tracheolar cell and the tracheal end organ in the control of oxygen entry into the lantern tissues, and the implications of the results in the oxygen regulation theory of flash control are discussed.
Anatomy of external structure and musculature of thoraces in the larva of the lepidopteran Pieris rapae crucivora
Authors: Tsujimura Hidenobu
Published: February 2005

In Pieris rapae the external structure of meso‐ and metathoraces includes intersegmental folds as well as 4 transverse shallow grooves on the dorsal side and 2 on the ventral side in addition to several leg segments. The musculature of both segments is very similar, but has some segment‐specificity. Sixty‐seven muscle are common to both hemi‐mesothorax and hemimetathorax. Four are specific for the mesothorax and 3 for the metathorax. Moreover, thickness and number of subdivisions of some common muscles are specific for one segment. Attachments areas of all muscles are clearly indicated on the pattern of cuticular grooves. They have a tendency to pile up or line up to form various sizes of united attachment sites, most of which are located on or near the cuticular groove. On the other hand all grooves have some muscle attachment sites. Thus, attachments of larval muscles may relate to formation of the grooves. Comparison of the musculature with that previously reported for some lepidopteran larvae shows a major common basic plan and minor interspecific variation. Its attachment sites allow the role of each muscle to be inferred for body contraction, bending, and twisting, and for leg direction and flexion.
Changes in ovarian ultrastructure and ecdysteroid titer during the aging process of female Xyleborus ferrugineus (Coleoptera: Scolytidae)
Authors: Norris D. M. , Chu H. M. , Rao K. D. P.
Published: February 2005

Striking ultrastructural and hormonal parameters of premature menopause and aging are reported in female Xyleborus ferrugineus fed cholesterol, rather than 7‐dehydrocholesterol, as a sole dietary sterol. The titer of free ecdysteroids in such 63‐day‐old females remained abnormally elevated through the period of the ovarian cycle. A similar plateauing of such elevated titer also occurred in 147‐day‐old, irregularly cycling females fed only cholesterol as the dietary sterol. These hormonal changes in menopausing X. ferrugineus females seem especially analogous to the maintenance of an elevated concentration of 17‐β‐estradiol through the estrous, as well as the proestrous, ovary of aged irregularly cycling rats. The highly abnormal ultrastructure of ovaries of X. ferrugineus females aged 216 days on a diet containing cholesterol as the sole sterol seems quite analogous to that of the nonovulatory follicles in older, irregularly cycling rats. Our new findings involving aging X. ferrugineus females indicate further the usefulness of an insect model to study aging processes.
Spatial organization in the saccule and lagena of a teleost: Hair cell pattern and innervation
Authors: Saidel William M. , Popper Arthur N.
Published: February 2005

The relationship between the hair cell orientation pattern and innervation in the saccule and lagena of the teleost Helostoma temmincki (the kissing gourami) was investigated with scanning electron microscopy and the Winkelmann‐Schmitt silver impregnation technique. The hair cell pattern in the saccule consists of four orthogonally oriented groups. The anterior two groups are oriented along the animal's rostrocaudal axis, and the posterior two are oriented along its dorsoventral axis. The pattern of hair cell orientations in the lagena is a typical bidirectional one. Two divisions of the eighth nerve innervate the saccule. The anterior division innervates the horizontally oriented hair cell groups, and the posterior division innervates the dorsoventrally oriented groups. A single nerve innervates the lagena, with the majority of fibers innervating one or the other of the two lagenar hair cell groups. The segregated pattern of innervation according to hair cell orientation groups in the saccule was confirmed in other species. Individual types of axonal terminations appear to innervate hair cells of specific ciliary bundle types.
Arterio‐Venous anastomoses in the gills of australian short‐finned eel, Anguilla australis
Authors: Donald J. A. , Ellis A. G.
Published: February 2005

Scanning electron microscopical examination of corrosion casts and critical point dried tissue of the gills of Anguilla australis showed that arterio‐venous anastomoses were present in both the afferent and efferent components of the gill vasculature. A morphometric distinction was made between anastomoses and capillaries within the gills. The origins of arteriovenous anastomoses from the filament arteries were bordered by specialized endothelial cells. The possible function of arterio‐venous anastomoses and the specialized endothelial cells is discussed.
Accuracy of bristle placement on a leg segment in Drosophila melanogaster
Authors: Held Lewis I. , Pham Tu T.
Published: February 2005

Bristle positions in two rows of bristles on the basitarsus of the second leg of the fruitfly Drosophila melanogaster were analyzed in order to determine the accuracy of bristle placement within these rows. Within each row the positions of the two terminal bristles were found to be approximately equally variable, and positional variability was found to increase toward the middle of each row. Rows having fewer bristles manifested more positional variability in their midsection. These results are interpreted in terms of a possible bristle spacing mechanism involving repulsive forces between mobile bristle cells.
Circulatory pathways in the sinusal spleen of the dog, studied by scanning electron microscopy of microcorrosion casts
Authors: Schmidt E. E. , Macdonald I. C. , Groom A. C.
Published: February 2005

Scanning electron microscopy of microcorrosion casts was used to visualize circulatory pathways in the sinusal spleen of dog. The examination of contracted versus dilated organs and variations of the volume of material injected gave an indication of flow dynamics. Minimal injections of material into contracted spleens produced filling of mainly the fastest routes for flow, whereas injections into dilated spleens primarily filled slower routes. This procedure yielded a more complete, three‐dimensional picture of the arterial, intermediate, and venous pathways as a whole, and of the relative amounts of flow through different arterial routes. Evidence of flow from capillary lumina out into ellipsoid sheaths was plentiful in casts from dilated spleens, but rare in casts from contracted organs. The pattern of flow within and out of the marginal sinus has been elucidated: A circumferential filling occurs first, followed by a flow that radiates outward into the marginal zone and red pulp. Venous sinuses filled via two routes in addition to the generally accepted path from the reticular meshwork via fenestrations in sinus walls. First, many venous sinuses extending out from the marginal sinus and surrounding marginal zone originated as open‐ended tubes continuous with the reticular spaces of the marginal sinus or marginal zone. Second, direct connections of arterial capillaries with venous sinuses in the red pulp were found. Evidence indicating that some mechanism is controlling the flow via these routes is discussed. The strikingly different arrangement of venous sinuses in the subcapsular region is demonstrated.
The intermediate circulation in the nonsinusal spleen of the cat, studied by scanning electron microscopy of microcorrosion casts
Authors: Schmidt E. E. , Macdonald I. C. , Groom A. C.
Published: February 2005

Scanning electron microscopy of microcorrosion casts was used to visualize circulatory pathways of the intermediate circulation in nonsinusal spleen of cat. The marginal sinus (MS) around lymphatic nodules is a distinct vascular space which fills preferentially before the filling of the marginal zone (MZ) and surrounding red pulp occurs. The MS, which has a plentiful vascular supply, does not usually enclose the nodule completely. From the MS, flow occurs radially outwards into the MZ. Corrosion casts and histological sections both showed that a diversity of forms of the MZ exists: The thickness of MZ and the arrangement of its reticulum vary among nodules and between different areas of the same nodule, from a complete absence to a region of up to 50 μn width.

No direct arteriovenous connections were found (in contrast to dog spleen: Schmidt et al., '83b). Aside from capillary endings in the MS and MZ, all arterial capillaries terminate in the reticular spaces of the red pulp, i.e., the circulation appears to be entirely “open.” From each capillary termination a great variety of flow pathways through the reticular meshwork to the pulp venules is available; some of these routes are quite long but others may involve distances as short as 15–25 μm. Evidence of flow into ellipsoid sheaths was abundant in casts from dilated spleens, but scarce in contracted spleens. In contrast to the extensive system of interconnected venous sinuses in dog spleen, the pulp venules found in cat spleen are nonanastomosing, shorter, and much smaller in caliber, and all receive flow freely from the reticular mesh‐work via open ends and fenestrations in their walls.
An ultrastructural study of oocyte growth within the endoderm and entry into the mesoglea in Actinia fragacea (Cnidaria, anthozoa)
Authors: Larkman Alan U.
Published: February 2005

Sea anemone gametes arise in the endoderm but migrate into the mesoglea at an early stage. In order to observe this process, large individuals of Actinia fragacea were collected from the same intertidal location at regular intervals over a 2‐year period, and their gonads were examined by light and electron microscopy.

The cellular origin of the oocytes is unclear, but the smallest recognizable oocytes are rounded cells, 6‐8 μm in diameter, with relatively large nuclei which may contain synaptinemalcomplexes. Their cytoplasm contains numerous ribosomes, a flagellar basal‐body‐rootlet complex, and distinctive dense structures also present in male germ cells but not found in anemone nonger‐ minal cells. During the endodermal phase of growth, the density of the oocyte nucleus increases, a single nucleolus becomes prominent, and mitochondria and glycogen accumulate in the cytoplasm. Most oocytes, but not all, only begin major vitellogenesis after entry into the mesoglea. Most oocytes enter the mesoglea before they attain a diameter of 25 μm.

The oocytes migrate toward and enter the mesoglea by a process resembling amoeboid movement. During entry, the oocytes are constricted into a characteristic “hourglass” shape and become covered by a basal lamina continuous with that of the gonad epithelium. The last part of the oocyte to enter the mesoglea forms an intimate relationship with the surrounding endodermal cells, which is maintained after entry is complete, and is thought to be important in the establishment of the trophonema.
Histochemical observations on the pyloric caeca of Asterias rubens (Echinodermata, asteroidea) in relation to the reproductive cycle
Authors: Van Der Plas A. J. , Voogt P. A.
Published: February 2005

The pyloric caeca of the starfish Asterias rubens were investigated histochemically during the reproductive cycle. The median duct and the side lobes reacted differently. The median duct reacted positively for acid phosphatases and glucose‐6‐phosphate dehydrogenase, whereas the side lobes reacted positively for alkaline phosphatases, neutral lipids, and fatty acids. In the transition zone between the median duct and the side lobes, the reaction for alkaline phosphatases and neutral lipids increased toward the side lobes. The function of the enzymes and the histochemical results are discussed in relation to the function of the pyloric caeca and to the reproductive cycle.
The development of the hexagonally structured egg envelope of the C‐O sole (Pleuronichthys coenosus)
Authors: Stehr Carla M. , Hawkes Joyce W.
Published: February 2005

The surface of a mature, pelagic C‐O sole egg is composed of polygonal chambers having four to eight sides, most of which are hexagonally shaped. This honeycomb pattern initially appears on primary oocytes as a thin layer of compact, electron‐dense material. Discrete thickenings begin to develop on the envelope of perinuclear stage oocytes. The thickenings lengthen and thin to form the hexagonal walls of the envelope in oocytes undergoing yolk vesicle formation. The walls of each hexagonal chamber occur in an area corresponding to the lateral margins of the adjacent follicle cell, suggesting that the hexagonal walls are produced by the follicle cells. The hexagonal layer is nearly complete at the beginning of vitellogenesis, and as vitellogenesis continues, a striated envelope layer composed of fibrillar lamellae develops between the oocyte and the hexagonal layer. The striated layer appears to be secreted by the oocyte. After vitellogenesis is completed, oocytes are ovulated and double in size during a period of maturation. Concurrently, the striated primary envelope stretches and thins into eight to nine horizontal lamellae. On the mature egg surface, the polygonal chambers are about 24–31 μm in diameter. Within each chamber there is a subpattern of polygonal areas; each polygon is 1.5–2.0 μm in diameter, and circumscribes a pore canal opening. This exceptional envelope may furnish the egg with some degree of protection, resiliency, and buoyancy, but its specific functions are not known.
The blood vascular system in the head of the herring gull (Larus argentatus)
Authors: Midtgård Uffe
Published: February 2005

The structure and development of the blood vascular system in the head of the herring gull (Larus argentatus) have been studied using injection techniques and histological sections. Three different but interconnected divisions of the arterial system are recognized in the adult: the cerebral carotid artery system, the external ophthalmic artery system, and the external carotid artery system. Embryologically, the arterial system is characterized by changes in the relative development of these three divisions; the cerebral carotid system being the most prominent in the first half of the embryonic period. The venous system is divided into two parts, the rostral cephalic system and the caudal cephalic system, which drain separate regions of the head. The Rete ophthalmicum, which is an arteriovenous network associated with the external ophthalmic artery system, can be identified from the fifth day of incubation, and its development appears to be coupled with changes in the arterial supply to the eye. The possibility of a homology between the Rete ophthalmicum of birds and the Rete caroticum of mammals is briefly discussed.
Fusion of ancestrulae germinated from statoblasts in plumatellid freshwater bryozoans
Authors: Mukai Hideo , Tsuchiya Masashi , Kimoto Kazuki
Published: February 2005

Upon germination of a statoblast, the shell is split into two valves; a mucous pad which represents the basal portion of the body wall of the incipient zooid or ancestrula then appears from between the valves; lastly, a tiny polypide evaginates at the opposite site. When two or more contiguously located statoblasts (floatoblasts or sessoblasts) of the same species germinate simultaneously, their mucous pads often come into contact with each other. The walls of the mucous pads then disappear in the contact areas, thus uniting the coeloms of the ancestrulae. This type of fusion between mucous pads of statoblast‐derived ancestrulae was ascertained in Plumatella emarginata, P. repens, P. casmiana, and Hyalinella punctata. The fusion is clearly species specific, and shows no clone specificity or allogeneic recognition. The fusibility test reported here seems to be a useful method for the examination of conspecificity in plumatellid bryozoans.
Effects of prolonged antitubulin culture on annulate lamellae in mouse α L929 fibroblasts
Authors: Kessel Richard G. , Katow Hideki
Published: February 2005

The fine structure of α L929 fibroblasts cultured in colchicine or vinblastine sulfate for periods as long as 48 hr was compared to control cells not exposed to antitubulins. In response to prolonged antitubulin culture, several changes in cell ultrastructure were noted: (1) Control fibroblasts contain cytoplasmic annulate lamellae (AL), but (2) prolonged exposure to either vinblastine sulfate or colchicine results in enhanced development of AL. (3) Single pore complexes are present in the rough‐surfaced endoplasmic reticulum (rER) in both control and antitubulin‐treated cells, but stacked porous cytomembranes also occur under both conditions. (4) Polyribosomes often are closely associated or continuous with the pore complexes. (5) Many antitubulin‐treated cells become multinucleate. Some nuclei in both control and antitubulin‐treated cells contain large and multiple nucleoli. (6) The large and multiple nucleoli are either attached directly to the inner membrane of the nuclear envelope or to infoldings of the nuclear envelope. (7) Antitubulin‐treated cells, after 48‐hr exposure, appear also to contain enhanced quantities of smooth‐surfaced endoplasmic reticulum (sER) and cytoplasmic filaments (and in some cells, lysosomes and rER as well) when compared to untreated cells. (8) In both control and colchicine‐treated cells, AL can exhibit continuity with either rER or sER. Further, (9) all three membrane systems may at times be continuous, but the quantity of these membranes appears to be greater in colchicine‐treated cells than in control cells. The results are discussed with respect to possible functional significance.
Intercellular bridges in ovaries of the newborn gerbil
Authors: McReynolds H. D. , Blanchet L. J. , Bowman D. C. , Hakim A. A. , Kiely M. L.
Published: February 2005

This study describes intercellular bridges in the ovaries of neonatal gerbils. Electron microscopy has revealed the presence of true intercellular bridges, connecting oogonia or oocytes, in ovaries of newborn gerbils. The cytoplasm of the intercellular channels is similar to that of the connected cells, with mitochondria, smooth and rough endoplasmic reticulum, and free ribosomes present. Lysosomes are also occasionally present in the intercellular bridges and they may be involved in early waves of oocyte atresia. An electrondense substance, 350–500 Å thick, is located immediately beneath the unit membrane of the intercellular bridges. Accumulation of electron‐dense material increases the thickness of the walls of the intercellular bridges, supporting and maintaining the patency of the channels. It is suggested that the intercellular channels probably allow the interchange of nutrients, organelles, and possibly regulatory materials as well.
Structure, crystallography, and morphogenesis of the cryptic shell of the terrestrial slug Limax maximus (Mollusca, gastropoda)
Authors: Furbish Dean Russel , Furbish William James
Published: February 2005

The structure and crystallography of the internal shell of the pulmonate gastropod slug Limax maximus were studied at the levels of light and scanning electron microscopy, revealing patterns of shell ontogeny and morphogenesis. The calcified portion of the slightly convex ovoid shell is composed of a single palisade layer of calcitic crystals. Numerous projections, 100 μm in width at the dorsal tip, are found on the dorsal surface of the shell and coincide with local nucleation sites of primordial calcium salt deposition onto the periostracum. With continued calcification these projections coalesce ventrally, forming the single crystalline shell layer. The organic portion of the shell includes the periostracum and an extensive PAS‐staining conchiolin. In EDTA‐etched preparations, conchiolin appears as a spongy network of fibers throughout the shell. Both horizontal and vertical components of the conchiolin are present, the former of variable thickness and occurring in an intercrystalline manner, the latter always occurring normal to the horizontal set. Macromorphogenic growth is characterized by three distinct temporal stages. Primary growth occurs radially from the umbonal region. Secondary growth is synonymous with shell thickening. Tertiary growth is characterized by both a lateral component, in which the shell extends beyond the primary growth boundaries, and a ventral component, in which the shell continues to grow in thickness. SEM of the ventral shell surface reveals a pattern of growth at the crystalmatrix interface. Proteinaceous fibers of the conchiolin occur unidirectionally in horizontal rows. Zones of incipient calcitic crystallization onto these hypostracal fiber bundles are contrasted by zones of increasing crystallization until the fibrous template (reduced hypostracum) is completely covered by crystals.
The cytoarchitecture of the torus semicircularis in the golden skink Mabuya multifasciata
Authors: Browner Robert H. , Baruch Alice M.
Published: February 2005

The skink, Mabuya multifasciata, torus semicircularis was subdivided into the central (CN), the laminar (LN), and the superficial (SN) nuclei using Golgi and Nissl methods. The central nucleus consisted of small ovoid neurons surrounding a core of fewer large ovoid‐triangular and fusiform neurons. The ovoid cells had scant cytoplasm and two to five dendritic trunks. Most of these processes were directed around the periphery of the central nucleus. The large neurons had clumped, darkly staining Nissl substance and a central nucleus. The sparse dendritic spine population on these cells increased distally on the three to five radiate dendrites. The laminar nucleus was present caudal and ventral to the central nucleus. At more rostral levels it was medial and dorsomedial to the central nucleus. The NL had three to five layers of ovoid and fusiform neurons. Scattered within these layers were a few ovoid‐triangular neurons. Ovoid neurons had eccentric or central nuclei. The arborization of their dendrites was generally medial and lateral but was frequently oriented caudomedial and rostrolateral. Fusiform neurons had pale Nissl substance, central nuclei, and one to two dendritic processes. The ovoid‐triangular neurons had dense, clumped Nissl substance and at least two dendritic trunks with few spines. The superficial nucleus was dorsal, lateral, and caudal to the central nucleus. Extending ventrolaterally around the central nucleus, the superficial nucleus became confluent with the laminar nucleus, ensheathing the central nucleus ventrally, laterally, and dorsally. Rostrally the central nucleus was covered by the layers of the laminar nucleus. Within the superficial nucleus were ovoid, fusiform and sparse ovoid‐triangular neurons. The study indicated that the morphology of the torus semicircularis in the golden skink was similar to that in other lizards. This similarity correlates with the degree of development as it relates to the auditory function, but was independent of the type of inner ear restraint mechanism.
Morphology of shell formation in eggs of the turtle Kinosternon flavescens
Authors: Packard Mary J. , Iverson John B. , Packard Gary C.
Published: February 2005

Shells from eggs of the turtle Kinosternon flavescens were examined during different stages of development with light and scanning electron microscopy. Prior to initiation of the calcareous layer, organic spheres or cores appear on the outer surface of the shell membrane. Presumably, these cores nucleate deposition of the mineral layer of the eggshell. Growing shell units of the mineral layer are rounded and nodular in shape, crystallites of adjacent shell units do not interlock, and numerous spaces occur between shell units. As growth continues, most of the spaces between shell units are obliterated, and shell units become more elongate in form. The calcareous layer of partially shelled eggs resembles the calcareous layer of flexible‐shelled eggs of emydids and chelydrids. Eggshells assume the morphology typical of rigidshelled chelonian eggs only at an advanced stage of shell formation. These observations indicate that rigid and flexible eggshells may form by fundamentally similar mechanisms, with length of shell growth being the primary determinant of whether shells are flexible or rigid.
Electron microscopic study of the innervation of the renal tubules and urinary bladder epithelium in Rana catesbeiana and Necturus maculosus
Authors: Tsuneki Kazuhiko , Kobayashi Hideshi , Gallardo Roberto , Pang Peter K. T.
Published: February 2005

The fine structure of the kidney and the bladder of the bullfrog (Rana catesbeiana), the bullfrog tadpole, and the mudpuppy (Necturus maculosus) were studied with special attention to the innervation of renal tubule cells and bladder epithelial cells. In the bullfrog kidney, nerve terminals and varicosities were frequently associated with the tubule cells, apparently in an increasing order from the proximal tubule to the connecting tubule. Although these terminals and varicosities did not directly contact the tubular cell membrane, an aggregation of synaptic vesicles on the side facing the tubule was considered as morphological evidence that neurotransmitter can be released here and can affect the transport activity of the tubule cells. The association of nerve varicosities with canaliculi cells in the connecting tubule was also demonstrated. In the bullfrog tadpoles, renal tubule cells were occasionally innervated. In the mudpuppy, renal tubule cells were only poorly innervated. The epithelium of the bullfrog bladder was commonly innervated. Nerve terminals with synaptic vesicles were located very near basal cells and even contacted them directly on rare occasions. In the mudpuppy, the innervation of the bladder epithelium was observed infrequently. The bullfrog tadpoles did not possess an apparent bladder. In all materials studied, renal arterioles and bladder smooth muscle cells were innervated.
The ear region of the marsupial sabertooth, Thylacosmilus: Influence of the sabertooth lifestyle upon it, and convergence with placental sabertooths
Authors: Turnbull William D. , Segall Walter
Published: February 2005

The mastoid auditory bulla of the extinct marsupial sabertooth, Thylacosmilus, has an enlarged, complex hypotympanic sinus but lacks an alisphenoid contribution. These are marked departures from the usual marsupial condition. Details of the ear region of Thylacosmilus are compared with those of the convergent, extinct placental sabertooth, Smilodon, and each is compared with less specialized related forms to define differences and similarities of the evolutionary paths that led to the striking overall convergence.

Functional factors such as pressure transformer ratio (PTR), impedance transformer ratio (ITR), acoustic impedence at the eardrum, and the fraction of the sound energy theoretically transmitted to the inner ear cannot be estimated for Thylacosmilus because certain critical measures are still unknown (tympanum size, ossicle lever arm ratios). However, in both sabertooths enlarged complex hypotympanic sinuses, characterized by expansions and contractions, are greatly developed. They vastly increase middle ear space (volume) and must have influenced these factors. In both, the sinuses provide the large air volume needed to prevent excessive damping of sound energy transmission (Hunt and Korth, '80), and both are believed to have achieved a further modulation of the system from the cushioning or “pillow” effect of the confined air as it directly damps the tympanum itself. Thylacosmilus has still another feature that may have given greater control over damping of sound energy transmission: the direct opening (probably membrane covered) of one of the sinus cavities into the side of the meatal tube. In this feature, as in others noted earlier (Turnbull, '76, '78), we see a greater degree of specialization in this marsupial sabertooth than in a placental counterpart.
Allogeneic recognition in sponges: Development, structure, and nature of the nonmerging front in Ephydatia fluviatilis
Authors: Buscema Marco , van de Vyver Gysèle
Published: February 2005

Whenever individuals of the freshwater sponge Ephydatia fluviatilis belonging to different strains come into contact, they reject each other by building a nonmerging front. The present work describes the development, the structure, and the nature of the barrier secreted between two individuals. The observations reported give unequivocal data about the collagen nature of the incompatibility barrier. First, ultrastructural investigations reveal the presence of fibrils and microfibrils which are, respectively, typical of collagen and spongin. Second, incorporation of tritiated proline, a characteristic precursor of collagen and related products, is particularly intense in the front. The involvement of several cell types in the barrier formation is discussed. The allogeneic incompatibility reaction between E. fluviatilis individuals appears very close to the process of allograft chronic rejection that we formerly described for some marine sponges. Both phenomena are basically analogous to the process which fixes to and isolates the sponges from their substrate.
Ultrastructure of the sensory epithelia of oral tube, fungiform sensory bodies, and terminal knobs of tentacles of Ovatella myosotis Draparnaud (Archaeopulmonata, Gastropoda)
Authors: Wondrak Günter
Published: February 2005

Sensory epithelia of the oral tube, a fungiform body anterior to the tentacles and of the terminal knob of tentacles, were studied in Ovatella myosotis by electron microscopy. All three epithelia consist of columnar support cells, sensory cells, and, except in the oral tube, numerous goblet cells. The epithelia differ significantly in their apical differentiations. In the oral tube an outer layer is formed by irregularly bent villi of support cells completely embedded in a surface coat. Cilia and cytofila of the dendrites of sensory cells intertwine throughout the entire depth of the villous layer. In the fungiform sensory body some of the villi of support cells are singly branched. Their basal region is free of a surface coat. In this region cytofila and cilia of dendrites form a spongy layer, some cytofila extending into the surface coat. In the tentacular terminal knob the villi of the support cells branch dichotomously once or twice, a single villus thus ending with 2–4 tips. Only these terminal twigs are invested with the surface coat. The cytofila and dendritic cilia are confined to a broad spongy layer underneath. Three types of dendrites are present. They differ in their number of cilia, structure of basal bodies and occurrence in the three epithelia. Dendritic cytofila are most abundant in the tentacular terminal knob and least numerous in the oral tube. The observations are discussed with respect to corresponding epithelia in other pulmonates, the homology of the fungiform body, and possible functional correlates of structural features.
Oral structures and their development in egg‐brooding hylid frog embryos and larvae: Evolutionary and ecological implications
Authors: Wassersug Richard J. , Duellman William E.
Published: February 2005

Among egg‐brooding hylid frogs there is much interspecific variation in the degree of development of the young at hatching. In certain species of Gastrotheca the eggs hatch into free‐living tadpoles, whereas in others (and in the genera Amphignathodon, Cryptobatrachus, Stefania and Hemiphractus) the eggs hatch directly into frogs. We examined the oral anatomy of tadpoles and embryos of 22 species of egg‐brooding hylids in order to determine the morphological differences between free‐living larvae and embryos of species having direct development. All free‐living Gastrotheca larvae are morphologically similar and have a large array of oral structures directly associated with a suspension feeding way of life. Among those egg‐brooding hylids without free‐living larvae there is a complete gradation from those with all of the free‐living tadpole oral structures to those with none. Different lineages retain different vestiges of free‐living larval morphology, suggesting that direct development has evolved multiple times among these frogs. All of the morphological patterns in the direct‐developing embryos can be accounted for by simple truncation or acceleration of the normal tadpole developmental program. We explore the possibility that certain Gastrotheca species with tadpoles may have evolved from species that lack larval stages. The development of oral structures in egg‐brooding hylids provides insight into the phylogenetic significance of these charactes in other groups of anurans. Most significantly they reinforce the idea that microhylids evolved from ranoidlike ancestors.
Morphology of the intestine of prefeeding and feeding adult Lampreys, Petromyzon marinus L.: The mucosa of the diverticulum, anterior intestine, and transition zone
Authors: Langille Robert M. , Youson John H.
Published: February 2005

Light and electron microscopy were used to examine the morphology of the mucosa of the diverticulum, anterior intestine, and transition zone in prefeeding and spontaneously feeding adult lampreys (Petromyzon marinus L.). Absorptive (either types A or B), ciliated, and enteroendocrine cells are present in all regions but the diverticulum and anterior intestine also possess zymogen (secretory) cells. Type A absorptive cells are restricted to the diverticulum and the rostral one‐third of the anterior intestine and are characterized by abundant mitochondria and an extensive smooth tubular network. Type B absorptive cells, in the remainder of the anterior intestine and the transition zone, possess small numbers of these organelles but in the transition zone also have inclusion bodies. During feeding, abundant lipid droplets and lipoprotein (VLDL) accumulate in the cytoplasm of both types of absorptive cells and in the lateral intercellular and the perivascular spaces. Lipid is present to a limited extent in ciliated cells and is encountered only rarely in enteroendocrine and zymogen cells. Although the animals are obligate sanguivores, there is little evidence of iron within these mucosal cells. It is suggested that intestinal efficiency displayed by this animal is due in part to ion transport in osmoregulation in type A cells, lipid absorption in types A and B cells, and digestion through enzymes in zymogen cells.
A three‐dimensional muscle model: A quantified relation between form and function of skeletal muscles
Authors: Woittiez R. D. , Huijing P. A. , Boom H. B. K. , Rozendal R. H.
Published: February 2005

A three‐dimensional muscle model with complex geometry is described and tested against experimental data. Using this model, several muscles were constructed. These muscles have equal optimum length but differ in architecture. The force exerted by the constructed muscles, in relation to their actual length and velocity of shortening, is discussed. Generally speaking, the constructed muscles with considerable pennation have great fiber angles, a great physiological cross section, a narrow active and steep passive length‐force relation, and a low maximal velocity of shortening. The maximal power (force times velocity) delivered by the constructed muscles is shown to be almost independent of the architecture of the muscles. The steepness of the passive length‐force relation is determined mainly by the shortest fibers within the group of constructed muscles, wheras maximal velocity of shortening and the width of the active length‐force relation are determined mainly by the longest fibers.

The validity of the three‐dimensional muscle model with respect to some morphological and functional characteristics is tested. Length‐force relations of constructed muscles are compared with the actual length‐force relations of mm. gastrocnemii mediales and mm. semimembranosi of male Wistar rats. Moreover, actual fiber angle, fiber length, and muscle thickness of three mm. gastrocnemii mediales are compared with values found for constructed muscles. It is concluded that the three‐dimensional muscle model closely approximates the actual muscle form and function.
Morphology of the intestine of prefeeding and feeding adult lampreys, Petromyzon marinus (L): The mucosa of the posterior intestine and hindgut
Authors: Langille Robert M. , Youson John H.
Published: February 2005

The epithelium of the posterior intestine and hindgut of recently metamorphosed adult lampreys (Petromyzon marinus L.) prior to and during spontaneous feeding was examined using light and electron microscopy. These two regions differ slightly in their general morphology but possess the same mucosal cell types. Included are caveolated absorptive and mucous cells, which are not present in more cephalic regions of the intestine, and ciliated and enteroendocrine cells. During feeding, the caveolated cells undergo dramatic transformation in their structure, namely, through the acquisition of numerous heterophagic vacuoles. Due to their morphology and to the fact that there are low amounts of lipid, it is suspected that caveolated cells are primarily involved in the absorption of protein components from the ingested host blood and body fluids. Iron in caveolated cells may result from the degradation of ingested heme or reflect the excretion of bile products at this location in the intestine. Mucous cells are likely responsible for lubrication of the luminal surface and may be important as a stem cell for the mucosal epithelium.
Models of tongue movement in the walrus (Odobenus rosmarus)
Authors: Gordon Kenneth R.
Published: February 2005

Three hypothetical models of tongue movement of the walrus during suction feeding are examined. These models encompass the entire range of simple tongue retraction movements possible by examining 1) movement of the tongue directly to the rear following the curvature of the palate, 2) to the rear and ventrally in a straight line, and 3) ventrally in a straight line. The percent of muscular force available from the hyoglossus, genioglossus, and styloglossus that could be applied toward retraction as predicted by each model is calculated. The resistance that the tongue would provide during retraction is calculated using projected tongue areas and is combined with the above data from the muscles to provide an estimate of the percent of the total available force that is needed to retract the tongue for each model. A separate examination of the direction of tongue‐induced wear striations on the palatal and lingual aspects of the teeth is used to help support or reject the three models.

The model where the tongue is moved directly to the rear is supported by studies of both muscle force and tooth wear. In the mammalian groups that were compared to the walrus, there is a great deal of interspecific variation in movements of the tongue during suction feeding; no two groups can be considered to have identical stereotyped tongue movements.
The cranial and cervical osteology of the european oystercatcher Haematopus ostralegus L.
Authors: Johnson R.
Published: February 2005

The cranial and cervical osteology of the European oystercatcher, Haematopus ostralegus L. is completely described from both whole skeletons and spirit specimens. Contrary to previous reports, the postorbital ligament shows variability in bifurcation and attachment, with the posterior branch, where present, attaching either to the suprameatic process or the zygomatic process. In addition, the quadrate ligament, which had been described as originating from the suprameatic process, appears instead to attach to the zygomatic process in some specimens. The caudal mandibular fenestra, earlier considered absent in oystercatchers, is present in all specimens examined. The cranium is additionally distinguished by a number of features which may be unique to oystercatchers. A fourth, previously unrecorded, division of the maxillopalatine strut is present, while the palatine process of the premaxilla is reduced to a thickening along the edge of the premaxillary process of the palatine. The distinctiveness of the oystercatcher cranium is particularly evident in the area of the quadratomandibular articulation, which possesses features potentially important for stabilizing the joint. A deep retroarticular notch is present, guiding a large medial jugomandibular ligament along the posterior margin of the articulation. A lateral mandibular tuberosity, which is received dorsally by an emargination of the jugal arch and quadrate, may act as an osteological brace, preventing posterior shifting of the closed mandible. The 15 cervical vertebrae are divided on the basis of structural criteria into three sections.
Form and function of the masticatory musculature in the tree sloths, Bradypus and Choloepus
Authors: Naples Virginia L.
Published: February 2005

The tree sloths, Bradypus and Choloepus, show unusual masticatory specializations, compared to each other and to other mammals. Both have an incomplete zygomatic arch with descending jugal process, a complex superficial masseter, a large temporalis and medial pterygoid musculature, and a lateral pterygoid with two heads. In Choloepus the deep masseter and zygomaticomandibularis are typical when compared to other mammals. However, in Bradypus there is an ascending jugal process from which enlarged and vertically oriented deep masseter and zygomaticomandibularis muscles originate. Although both sloths are folivores, the anterior teeth in Choloepus are caniniform, while those of Bradypus have lost such elongation. In both sloths the glenoid cavity is similarly located; however, in Bradypus the cranioman‐dibular joint is raised above the occlusal plane, and the pterygoid flanges are elongated.

Prediction of the evolutionary sequence of cranial changes from Choloepus‐ like (primitive) to Bradypus‐ like (derived) morphology is based upon the most parsimonious model of masseter‐medial pterygoid complex changes for masticatory efficiency improvement. The model proposes that the condylar neck in Bradypus was elongated and that this single change predicated a series of other structural changes.

Mandibular movement patterns in both sloths showed anteromedially directed unilateral power strokes as in other mammals. Puncture‐crushing, tooth‐sharpening, and chewing cycles are distinct in Choloepus, less so in Bradypus. The masticatory rate is slow in sloths compared to other mammals of similar body size, averaging 590 ms per cycle for Choloepus and 510 ms for Bradypus.
Oogenesis in the terrestrial hermit crab Coenobita clypeatus (decapoda, anomura). I. Previtellogenic oocytes
Authors: Komm Barry S. , Hinsch Gertrude W.
Published: February 2005

Ultrastructural study of previtellogenic oocytes found in cystlike clusters scattered throughout the length of the bilobed ovary of the hermit crab Coenobita clypeatus shows a high nuclear:cytoplasm ratio. Large, round nuclei containing synaptinemal complexes serve as good temporal markers for identification of previtellogenic oocytes. The cytoplasm contains many smooth‐membraned vesicles filled with granules and probably of nuclear origin. In addition to its complement of Golgi complexes, endoplasmic reticulum, mitochondria, and free ribosomes, the cytoplasm also contains stacks of annulate lamellae, a feature not previously described for decapod oocytes. Typically, the previtellogenic oocyte with its accumulation of ribosomes has the appearance of a nonsynthetic cell preparing to go through a metabolic transition.