bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology, histochemistry and physiology of the major salivary glands in the echidna Tachyglossus aculeatus (Monotremata)
Authors: van Lennep E. W. , Kennerson A. R. , Young J. A. , Hales J. R. S.
Published: February 2005

The three major salivary glands of the monotreme echidna are described. The parotid is a typical serous gland with tubulo‐acinar secretory endpieces and a well‐developed system of striated ducts. The mandibular gland, although light microscopically resembling a mucous gland, secretes very little glycoprotein. Its cells are packed instead with serous granules, resembling in fine structure the “bull's eye” granules in the mandibular gland of the European hedgehog Erinaceus europaeus. The sublingual glands secrete an extremely viscous mucous saliva. Expulsion of this saliva through the narrow ducts is probably aided by contraction of the extensive myoepithelial sheaths surrounding the secretory tubules. Application of the glyoxylic acid induced fluorescence method failed to demonstrate adrenergic innervation in any of the glands.
Mandibular function in Galago crassicaudatus and Macaca fascicularis: An in vivo approach to Stress Analysis of the mandible
Authors: Hylander William L.
Published: February 2005

Single‐element and/or rosette strain gages were bonded to mandibular cortical bone in Galago crassicaudatus and Macaca fascicularis. Five galago and eleven macaque bone strain experiments were performed and analyzed. In vivo bone strain was recorded from the lateral surface of the mandibular corpus below the postcanine tooth row during transducer biting and during mastication and ingestion of food objects.

In macaques and galagos, the mandibular corpus on the balancing side is primarily bent in the sagittal plane during mastication and is both twisted about its long axis and bent in the sagittal plane during transducer biting. On the working side, it is primarily twisted about its long axis and directly sheared perpendicular to its long axis, and portions of it are bent in the sagittal plane during mastication and molar transducer biting. In macaques, the mandibular corpus on each side is primarily bent in the sagittal plane and twisted during incisal transducer biting and ingestion of food objects, and it is transversely bent and slightly twisted during jaw opening. Since galagos usually refused to bite the transducer or food objects with their incisors, an adequate characterization of mandibular stress patterns during these behaviors was not possible. In galagos the mandibular corpus experiences very little transverse bending stress during jaw opening, perhaps in part due to its unfused mandibular symphysis.

Marked differences in the patterns of mandibular bone strain were present between galagos and macaques during the masticatory power stroke and during transducer biting. Galagos consistently had much more strain on the working side of the mandibular corpus than on the balancing side. These experiments support the hypothesis that galagos, in contrast to macaques, employ a larger amount of working‐side muscle force relative to the balancing‐side muscle force during unilateral biting and mastication, and that the fused mandibular symphysis is an adaption to use a maximal amount of balancing‐side muscle force during unilateral biting and mastication.

These experiments also demonstrate the effects that rosette position, bite force magnitudes, and types of food eaten have on recorded mandibular strain patterns.
Tooth crown morphology in caecilians (Amphibia: Gymnophiona)
Authors: Wake Marvalee H. , Wurst Gloria Z.
Published: February 2005

The morphology of tooth crowns is variable inter‐specifically among caecilians. Cusp number and shape, crown dimensions, and crown curvature characterize various species and have both functional and phylogenetic implications. Ichthyophis, Uraeotyphlus, Hypogeophis, and Geotrypetes have bicuspid teeth; Dermophis, Gymnopis, Caecilia, and Typhlonectes monocuspid. Crown morphology as revealed by scanning electron microscopy is associated with prey grasping and, in one case, possible specialization of prey type.
Partial regeneration of the above‐elbow amputated rat forelimb. I. Innate responses
Authors: Person P. , Libbin R. M. , Shah D. , Papierman S.
Published: February 2005

Although a number of recent studies describe the facilitation of limb regeneration by electrical and other forms of stimulation, little is known of innate regenerative capacity in the mammalian limb. The present report describes spontaneous regenerative responses following subtotal forelimb amputation in the young white rat. In one group of animals the forelimb was amputated through the lower humerus and the skin sutured closed. In a second group, adjacent muscle tissue still attached to bone at its origin(s) was interposed between the cut surface of the humerus and the skin. Among animals of the first group (skin closure only) bone growth and limb regenerative responses were generally not observed. Animals of the second group displayed significant elaborations of cartilage and bone at the limb terminus. The appearance and subsequent modification of these tissues suggest that some capacity for limb regeneration exists innately in the young rat and can be more readily evoked than has been recognized heretofore. It is concluded that extant and forthcoming reports of electrically stimulated skeletal tissue growth, repair and regeneration among eutherial mammals should be examined to determine whether reported responses to stimulation represent advances beyond what might be expected from innate replacement processes alone.
Chemoreceptors in the cibario‐pharyngeal pump of the cabbage looper moth, Trichoplusia ni (Lepidoptera: Noctuidae)
Authors: Eaton John L.
Published: February 2005

The structure of contact chemoreceptors in the cibariopharyngeal pump of the moth Trichoplusia ni (Lepidoptera: Noctuidae) is described. Two types of receptors designated A and B are located on the floor of the pump. Two groups of 9‐12 A receptors are located in the anterior part of the pump, and two groups of two B receptors are in the posterior part of the pump. Five sensory dendrites extend to the tip of each A receptor and four to each B receptors. Available evidence indicates that these receptors are contact chemoreceptors and do not serve as mechanoreceptors. The receptors are compared to those of other insects.
Organization of nucleus rotundus, a tectofugal thalamic nucleus in turtles. I. Nissl and Golgi analyses
Authors: Rainey W. Todd
Published: February 2005

This study consists of a detailed cytoarchitectonic and Golgi analysis of a major tectofugal thalamic nucleus in the red‐eared turtle, Pseudemys scripta elegans. Neurons in nucleus rotundus have a unimodal soma size distribution and a common dendritic branching pattern. They have long dendrites which undergo sparse, dichotomous branchings and contribute to dendritic fields that cover a third to half the dimensions of the nucleus. Spicules, 1‐2 μ long, and complex appendages, 5‐20 μ long, are found with low density on many dendrites in Golgi‐Kopsch material. A few cells have beaded dendritic processes. Three cytoarchitectural regions can be differentiated in nucleus rotundus: a shell, a cell‐poor region and a core. The shell is a monolayer of somata forming the peripheral boundary of most of the nucleus. The cell‐poor region forms a thin zone concentric with and internal to the shell. Shell cells send some of their dendrites concentrically within this zone and others radially into the core region. Core neurons are dispersed within the neuropil of the nucleus and usually have spherical dendritic fields. However, peripheral core neurons have asymmetrical fields, so their dendrites do not extend beyond the shell. Caudomedial and central subregions of the core can be defined on the basis of neuronal density and cytology. Somata in the caudomedial area of the core are densely packed and have slightly darker staining cytoplasm than those in the central subregion. However, their dendrites are similar to those of the central core neurons. There is extensive dendritic overlap between the two subregions.
Histochemical and ultrastructural features of the aorta of the slug (Limax maximus)
Authors: Curtis Sherill K. , Cowden Ronald R.
Published: February 2005

As a part of a continuing study of unusual molluscan tissues, the “chondroid” tissue (Hyman, '67) associated with the anterior and posterior aortae of the slug (Limax maximus) was examined by light and electron microscopy. Unlike the odontophoral tissue of this species (Curtis and Cowden, '77), the “chondroid” tissue comprising the adventitial layer of the aorta consists of large, glycogen‐filled cells with characteristic arrays of pores in their plasma membranes resembling those of the “globular” cells (Rogers, '69; Fernandez, '71); “fibrocytes” (Nicaise et al., '66; Baleydier et al., '69; Nicaise, '73); “Blasenzellen” or “Leydig” cells (Wondrak, '69; Stang‐Voss, '70; Buchholz et al., '71; Stang‐Voss and Staubesand, '71; Wolburg‐Buchholz, '72); or “pore” cells (Sminia, '72; Beltz, '77) of other mollusks. The anterior and posterior aortae are very similar in organization, except that the anterior aorta is larger in diameter; its wall is thinner; and it lacks calcification. Both the anterior and posterior aortae possess a loosely organized (incomplete) endothelial layer surrounded by two layers of innervated smooth muscle. The smooth muscle cells possess fibrous surface specializations resembling hemidesmosomes as well as large numbers of tubular or rounded vesicles in association with their plasma membranes. Blood cells (amoebocytes) containing large glycogen deposits and distinctive membrane‐enclosed cytoplasmic inclusions can be found occasionally in the walls of the vessels.
Countercurrent blood vessel arrangement in beaver (Castor canadensis)
Authors: Cutright Warren J. , McKean Tom
Published: February 2005

The vascular anatomy of five beavers (Castor canadensis) was studied by dissection and injection of arteries and veins with vinyl acetate. There is extensive countercurrent arrangement of arteries and veins distal to and including the common iliac artery and veins. Two types of countercurrent vessels occur (1) a venae comitantes type in which two or three veins surround a central artery, and (2) a modified rete type. The retia are located proximal to the large flat tail and the webbed hind feet. Two bypass veins are described for the feet and tail and the significance of these structures in temperature regulation is stressed.
Keratin formation and barrier mechanisms in the epidermis of Natrix natrix (Reptilia: Serpentes): An ultrastructural study
Authors: Landmann Lukas
Published: February 2005

A β‐keratin pattern, consisting of 30 Å filaments embedded in an amorphous matrix, is formed by fusion of membrane‐bound packets with the 70 Å filaments of immature cells. This pattern occurs in the Oberhäutchen and the β‐layer. When completely mature, these two components show no cell boundaries. It is suggested that this feature is associated with the process that leads to the separation of outer and inner epidermal generation. Filaments of 100‐150 Å embedded in an amorphous matrix form the α‐keratin pattern, which occurs in the α‐layer only. The lacunar tissue is regarded as consisting of cells resembling immature α‐cells, whereas mesos and clear layer show a keratin‐like material consisting of 100‐150 Å filaments without matrix. This is regarded as a modification of α‐keratin. The cells of all components synthesizing α‐keratin (α, mesos and clear layer) have the following features in common: (1) the plasma membrane is modified in that its inner leaflet is obscured by the deposition of a marginal layer, and (2) the cells have 0.06‐0.1 μm mucous granules containing mucopolysaccharides, which release their content into the intercellular space.

Protective and barrier functions of the epidermis are provided by the following features: (1) Oberhäutchen and β‐layer merge during final maturation to a homogenous stratum of β‐keratin without intercellular spaces. Their function seems to be mechanical protection. (2) The marginal layer of α‐keratin containing cells, which decreases in thickness from without inwards, is highly resistant to physical and chemical influences. (3) Mesos granules contain phos‐pholipid‐lamellae, which are partly discharged into the intercellular space and partly remain within the mesos cells. These lipid lamellae are believed to contribute to the establishment of the permeability barrier. (4) The content of mucous granules may play a role in immunological processes. (5) Tight junctions seal off the intercellular space between the uppermost living cells of the epidermis and contribute to the permeability barrier.
Colic modifications in iguanine lizards
Authors: Iverson John B.
Published: February 2005

All lizard species of the subfamily Iguaninae except Amblyrynchus cristatus possess from one to eleven transverse valves in the proximal colon. Valves are of two kinds: circular (sometimes with a sphincter valve) or semilunar. Circular valves (if present) always occur proximally to semilunar valves. Intraspecific variation in the number and type of valves is small, but increase with modal number of valves. No significant ontogenetic change in number of valves could be demonstrated. Colic valves in iguanine lizards apparently evolved as simple infoldings of the medical colic wall.

Comparisons are made with colic modifications occurring in other lizard families. Herbivorous species of the Scincidae, Agamidae, and Iguanidae are the only lizards known to exhibit colic partitioning, suggesting that the evolution of these structures is intimately related to the evolution of herbivory in these lizards. The potential taxonomic and phylogenetic importance of lizard colon anatomy is discussed.
Regeneration of colonic mucosa in the rat
Authors: Brackett Kim A. , Townsend Samuel F.
Published: February 2005

As part of a study of ulcer formation and healing, regeneration of colonic mucosa in rats was studied following placement of a surgical lesion. Alterations in mucosubstances and connective tissue were examined and their possible significance discussed.

The sequence of events in healing was: (1) The mucosa adjacent to the lesion tipped into the lesioned area. The crypts in this mucosa became lined with cells which contained no mucus and had no striated borders. Later in the experimental period, these undifferentiated cells gave rise to cells containing carboxymucins. Cells containing sulfomucin, neutral mucin, or having striated borders arose from the carboxymucin cells. (2) An epithelial ledge of undifferentiated cells migrated onto a sulfated glycosaminoglycan, fibrous interface between necrotic and living tissue in the lesion. (3) Crypt formation began with the appearance of intraepithelial anlagen. (4) Crypts lengthened by a process of epithelial‐connective tissue proliferation from the base of the crypt upwards. Following completion of connective tissue regeneration, crypts formed by invading the reestablished lamina propria. (5) The first mucous cells in the ledge contained carboxymucins. As crypt formation occurred, these cells gave rise to typical columnar absorptive cells, to cells containing sulfomucins, and to cells containing neutral mucins. (6) Lengthening of crypts ceased following the appearance of a sulfated acid glycosaminoglycan—collagenous layer deep in the submucosa.
Quantitative assay of electromyograms during mastication in domestic cats (Felis catus)
Authors: Gorniak Gerard C. , Gans Carl
Published: February 2005

Mastication has been studied by cinematography with synchronized electromyography (computer quantified and analyzed), while unanesthetized, freely feeding cats (Felis catus) were reducing equivalent‐sized chunks of raw and cooked beef and cooked chicken. Cats reduce food on one side at a time, and their chewing cycles show both horizontal and anteroposterior deflections. Food objects are shifted from side to side by lateral jerks of the head and movements of the tongue.

During the opening phase, the lower jaw is rotated relatively straight downward, and the digastric muscles are active in bilateral symmetry. Near the end of opening, the head jerks upward, both zygomaticomandibulares start to fire, and opening acceleration of the mandible decreases. Closing starts with horizontal displacement of the mandibular canines toward the working side, accompanied by asymmetrical activities from the working side deep temporalis and the balancing side medial pterygoid, as well as a downward jerk of the head. As closing proceeds, the mandibular canines remain near the working side and the working side zygomaticomandibularis and deep masseter are very active. Near the end of closing, the mandibular canine on the working side moves toward the midline, and adductors, digastrics, and lateral pterygoids of both sides are active. The adductors of the working side are generally more active than those of the balancing side.

During a reduction sequence, the number and shape of the masticatory cycles, as well as movements of the head, during a reduction sequence are affected significantly by food type. As reduction proceeds, the duration of bite and the muscular activity (as characterized by number and amplitude of spikes) change significantly among muscles of the working and balancing sides. The adductors of the working side are generally most active when cats chew raw beef, less for cooked beef, and least for cooked chicken. In general, the adductor activity reflects food consistency, whereas that of the digastrics and lateral pterygoids reflects more the vertical and lateral displacements of the mandible. Statistical analysis documents that the methods of electrode insertion and test give repeatable results for particular sites in different animals. Thus, it should be possible to compare these results with those produced while other mammalas are masticating.
The ultrastructure of the otolithic membrane and otolith in the juvenile mummichog, Fundulus heteroclitus
Authors: Dunkelberger Dana G. , Dean John Mark , Watabe Norimitsu
Published: February 2005

The sagitta otolithic membrane of Fundulus heteroclitus consists of two different zones. A structured zone (gelatinous layer), which usually exhibits a reticulated or honeycomb‐like architecture, is composed of tightly arranged fibrous material and covers only the sensory region of the macula. The gelatinous layer extends from the otolith surface to the tips of the sensory hairs, and probably functions primarily as a mechanoreceptor. The arrangement of this zone is closely associated with specific overlying structural features of the otolith surface and may also influence the pattern of mineral deposition to some degree. A nonstructured zone (subcupular meshwork) consists of fibers in very loose networks and covers both sensory and nonsensory regions of the macula. Over the sensory region, some of this fibrous material extends from the epithelial surface, through pores in the gelatinous layer, to the surface of the overlying otolith. In the nonsensory region, fibers of the subcupular meshwork are relatively more numerous and extend around the peripheral margin of the otolith. Evidence is presented which suggests that the fibrous material of the subcupular meshwork is incorporated into the otolith as an organic matrix constituent. New aspects on the ultrastructure of the otolith are presented and discussed.
Fine structure and distribution of epidermal projections associated with taste buds on the oral papillae in some loricariid catfishes (Siluroidei: Loricariidae)
Authors: Dana Ono R.
Published: February 2005

Two morphologically distinct structures occur on the surfaces of the oral papillae in several loricariid catfish species; namely, (1) typical vertebrate taste buds composed of receptor and sustentacular cells and (2) brushlike projections, termed epidermal brushes, that represent specialized epidermal cells containing keratin. Both of these structures were studied with the combined use of light microscopy and scanning and transmission electron microscopy. The general body surface, fins, and rostral cutaneous processes of some loricariid catfishes are covered with taste or terminal buds but lack the epidermal brushes. It is suggested that the epidermal brushes found on the oral papillae serve as protective devices for the taste buds and as abrasive surfaces for substrate scraping during feeding. The taste buds on the oral papillae may detect any gustatory stimuli from the resulting substrate disturbance. Comparative studies reveal many differences in the number and spatial arrangement of these two structures on the oral papillae among the several species of the Loricariidae examined. These differences may represent functional adaptations to the various modes of life in the Loricariidae.
The functions of the lumbar spine during stepping in the cat
Authors: English Arthur Wm.
Published: February 2005

To examine the functional roles played by the lumbar spine during overground stepping, seven adult cats were run in electromyographic (EMG) experiments. Recordings were made bilaterally from mm. iliocostalis, longissimus dorsi and multifidus at a single vertebral level (L3) and from m. rectus abdominis. Stepping movements were monitored synchronously either by videotape or by high speed cinematography. During alternate use of the hindlimbs (walking and trotting), both epaxial and abdominal muscles were active bilaterally and biphasically. During in‐phase use of the hindlimbs (galloping and half‐bounding), single bursts of activity were observed. Phasic bursts of activity in rectus abdominus were reciprocal to those of epaxial muscles. Second bursts of activity in either group were noted infrequently. Recordings from the same back muscle at several vertebral levels indicated little difference from these patterns. Movements of the lumbar spine during galloping and half‐bounding steps, both angular and linear, are easily correlated with muscle activity patterns. Movements of the lumbar spine during walking and trotting show no particular pattern. Only small angular and linear movements are found. It is concluded that the lumbar spine contributes substantially to step length and limb speed during galloping and half‐bounding steps and the epaxial and abdominal musculature may also act as elastic bodies. During walking and trotting steps, the epaxial muscles are proposed to act to stabilize the pelvic girdle to provide a firm base for limb muscles which arise on the pelvis and are synchronously active.
Intrinsic organization of snake lateral cortex
Authors: Ulinski Philip S. , Rainey W. Todd
Published: February 2005

Lateral cortex is the most laterally placed of the four cortical areas in snakes. Earlier studies suggest that it is composed of several subdivisions but provide no information on their organization. This paper first investigates the structure of lateral cortex in boa constrictors (Constrictor constrictor), garter snakes (Thamnophis sirtalis), and banded water snakes (Natrix sipedon) using Nissl and Golgi preparations; and secondly examines the relation of main olfactory bulb projections to the subdivisions of lateral cortex using Fink‐Heimer and electron microscopic preparations.

Lateral cortex is divided on cytoarchitectonic grounds into two major parts called rostral and caudal lateral cortex. Each part is further divided into dorsal and ventral subdivisions so that lateral cortex has a total of four subdivisions: dorsal rostral lateral cortex (drL), ventral rostral lateral cortex (vrL), dorsal caudal lateral cortex (dcL) and ventral caudal lateral cortex (vcL). Systematic analyses of Golgi preparations indicate that the rostral and caudal parts each contain distinct populations of neurons. Rostral lateral cortex contains bowl cells whose dendrites arborize widely in the outer cortical layer (layer 1). The axons of some bowl cells can be traced medially into dorsal cortex, dorsomedial cortex and medial cortex. Caudal lateral cortex contains pyramidal cells whose somata occur in layers 2 and 3 and whose dendrites extend radially up to the pial surface. In addition, three populations of neurons occur in both rostral and caudal lateral cortex. Stellate cells occur in all three layers and have dendrites which arborize in all directions. Double pyramidal cells occur primarily in layer 2 and have dendrites which form two conical fields whose long axes are oriented radially. Horizontal cells occur in layer 3 and have dendrites oriented concentric with the ependyma. Fink‐Heimer preparations of snakes which underwent lesions of the main olfactory bulb show that the primary olfactory projections to cortex are bilateral and restricted precisely to rostral lateral cortex. Electron microscopic degeneration experiments indicate that the olfactory bulb fibers end as terminals which have clear, spherical vesicles and asymmetric active zones. The majority are presynaptic to dendritic spines in outer layer 1.

These studies establish that lateral cortex in snakes is heterogeneous and contains two major parts, each containing two subdivisions. The rostral and caudal parts have characteristic neuronal populations. Primary olfactory input is restricted to rostral lateral cortex and seems to terminate heavily on the distal dendrites of bowl cells. Axons of some of these cells leave lateral cortex, so that the rostral lateral cortex forms a direct route by which olfactory information reaches other cortical areas. The functional role of caudal lateral cortex is not clear.
Ultrastructural morphology of the shell and shell membrane of eggs of common snapping turtles (Chelydra serpentina)
Authors: Packard Mary J.
Published: February 2005

Common snapping turtles (Chelydra serpentina) lay nearly spherical, flexible‐shelled eggs having an outer mineral layer composed of calcium carbonate in the aragonite form. The mineral layer is arranged into loosely organized groups of nodular shell units, with numerous spaces (or pores) between adjacent shell units. Shell units are structurally complex, consisting of an inner tip that is morphologically distinct from the main body of the shell unit. Contained within an intact shell unit at the interface of the tip and the main part of the shell unit is the central plaque, an apparent modification of the shell membrane that may serve to nucleate calcification of shell units during shell formation. The tips of shell units are firmly attached to a single, multilayered shell membrane throughout much of incubation. The calcareous layer begins to detach from the shell membrane about half‐way through incubation, and changes in shell morphology attending this detachment indicate that snapping turtles may use the shell as a source of calcium during embryogenesis. The arrangement of the mineral layer into groups of shell units, the large number of spaces between shell units, and little or no interlocking of crystallites of adjacent shell units apparently are factors contributing to the ability of these eggs to swell as they absorb water.
Functional morphology of the masticatory musculature of the rodent subfamily microtinae
Authors: Kesner M. H.
Published: February 2005

Voles and lemmings are the most successful group of graminivorous rodents, but the adaptations allowing them to enter this niche are not fully known. Dissections of the masticatory musculature of the 12 genera and subgenera of North American microtines show an increase in the potential anterior vector component and in the potential vertical vector component of these muscles relative to the molar tooth row. The result is a separation of the compressive and propulsive functions of the masticatory muscles during the power stroke of mastication. This has led to the formulation of a propalinal “swing” hypothesis which is supported by vector analyses of the musculature.
Intercellular bridges and the fusome in the germ cells of the Cecropia moth
Authors: Mandelbaum Isabel
Published: February 2005

Intercellular bridge development was compared in Ceropia by transmission electron microscopy in the germ cells of males and females. Bridge formation begins in the fourth instar, and the spindle remnants in newly formed bridges are replaced at this time by an amorphous material known as the fusome. In the four‐ and eight‐celled cystocyte clusters of the female, the newly formed intercellular bridges migrate centripetally, forming a central complex of bridges surrounded by a rosette of germ cells. The fusomes become continuous and occupy all of the bridges in the complex. At each division each mitotic spindle orients itself with one pole toward the continuous fusome. In the female, mitosis stops at the eight‐cell stage, and the cystocytes all enter first meiotic prophase. At the end of the fifth instar, when nurse cell differentiation commences in seven of the cells, the continuous fusome is replaced by a continuous mass of mitochondria and microtubules. In the male, bridge migration and rosette formation are abandoned during the later mitotic and meiotic divisions; during these stages the fusome is no longer continuous. The fusome of males disappears during spermatid differentiation and is not replaced by mitochondria and microtubules. The ability of the centrally located continuous fusome to orient the mototic spindles of succeeding mitoses could account for the earlier observations that all pre‐existing bridges remain in only one of the daughter cells at each successive cystocyte division in the female.
Ultrastructure of siliceous spicules and microsclerocytes in the marine sponge Neofibularia irata N. SP.
Authors: Wilkinson Clive R. , Garrone Robert
Published: February 2005

The marine sponge Neofibularia irata contains four different categories of siliceous spicules. These spicules are evident in the tissues as distinct bundles that act to increase the structural rigidity of the sponge. All spicules have a normal structural morphology with silica deposition around a hexagonal axial canal containing a crystalline axial filament. The megasclere strongyles are secreted in typical megasclerocytes. The sigma and raphid microscleres are secreted in individual microsclerocytes that are grouped together in parallel to form loose bundles. However, the microxea microscleres are apparently secreted in distinct tight bundles (trichodragmas) within a single cell. These cells, containing between 13 and 39 spicules, are grouped to form large packets of bundles of spicules.
A fine structural study of the testicular wall and spermatogenesis in the crinoid, Florometra serratissima (Echinodermata)
Authors: Bickell Louise R. , Chia Fu‐Shiang , Crawford Bruce J.
Published: February 2005

The testicular wall and the process of spermatogenesis in the crinoid, Florometra serratissima, has been studied at the fine structural level. The testicular wall is composed of three layers: a perivisceral layer consisting of nerve processes, muscle fibers, and epithelial cells; a haemal sinus containing haemal fluid, collagen‐like fibers, and haemocytes; and a germinal layer consisting of germinal and interstitial cells.

The germinal layer is elaborated into numerous folds that project into the lumen of the testis and a branch of the haemal channel extends through the core of each fold. Evidence suggesting that nutrients are carried to the testis and germinal cells via the haemal system is presented. Spermatogonia are concentrated around the base of each fold and spermatocytes line the more distal regions. Spermatids occur at the luminal surface of the germinal layer and spermatozoa fill the testicular lumen. Interstitial cells phagocytize spermatozoa and may also transfer nutrients to spermatids.

The nucleus of spermatogonia is large and contains one or two nucleoli. The cytoplasm contains numerous organelles, lipid granules, and a distal and proximal centriole, each with a satellite complex. A striated rootlet extends from the distal centriole. During first meiotic prophase, the distal centriole loses its striated rootlet and produces a flagellum, the proximal centriole loses its satellite complex, the nucleolus disappears, and proacrosomal vesicles are synthesized by the Golgi complex. During spermiogenesis, most of the mitochondria appear to fuse to form a single, large mitochondrion, the nuclear chromatin condenses, and superfluous cytoplasm is lost by autophagocytosis. The formation and definitive positioning of the acrosomal vesicle and periacrosomal material at the apex of the nucleus is described in detail.
Morphology of the gastrointestinal tract in primates: Comparisons with other mammals in relation to diet
Authors: Chivers David J. , Hladik C. M.
Published: February 2005

Three categories of dietary adaptation are recognized—faunivory, frugivory, and folivory—according to the distinctive structural and biochemical features of animal matter, fruit, and leaves respectively, and the predominance of only one in the diets of most species.

Mammals subsisting mainly on animal matter have a simple stomach and colon and a long small intestine, whereas folivorous species have a complex stomach and/or an enlarged caecum and colon; mammals eating mostly fruit have an intermediate morphology, according to the nature of the fruit and their tendency to supplement this diet with either animal matter or leaves. The frugivorous group are mostly primates: 50 of the 78 mammalian species, and 117 of the 180 individuals included in this analysis are primates.

Coefficients of gut differentiation, the ratio of stomach and large intestine to small intestine (by area, weight, and volume), are low in faunivores and high in folivores; the continuous spread of coefficients reflects the different degrees of adaptation to these two dietary extremes.

Interspecific comparisons are developed by allowing for allometric factors. In faunivores, in which fermentation is minimal, the volume of stomach and large intestine is related to actual body size, whereas these chambers are more voluminous in larger frugivores and mid‐gut fermenting folivores; fore‐gut fermenters show a marked decrease in capacity with increasing body size. Surface areas for absorption are related to metabolic body size, directly so in frugivores; area for absorption is relatively less in larger faunivores and more in larger folivores, especially those with large stomachs.

Indices of gut specialization are derived from these regressions by nonlinear transformation, with references to the main functional features of capacity for fermentation and surface area for absorption.

These are directly comparable with the dietary index, derived from quantitative feeding data displayed on a three‐dimensional graph, with all species within a crescentic path from 100% faunivory through 557ndash;80% frugivory to 100% folivory, perhaps illustrating, at least for primates, the evolutionary path from primitive insectivorous forms through three major ecological grades.
Prenatal development of the microphthalmic eye in the golden hamster
Authors: Jackson Caroline Goode
Published: February 2005

Prenatal development of the eye in a microphthalmic hamster strain (“anophthalmic white”) is compared with established normal developmental periods. The mutant eye primordium is first distinguished at an average of ten gestational days (Period 6) by an incompletely invaginated optic cup, uniformly pseudostratified outer neuroepithelial layer and widely separated margins of the optic fissure. The outer layer of the mutant cup subsequently becomes abnormally thickened, especially posteriorly and midventrally, and, except in a few eyes with localized imperfect fusion, the optic fissure is unfused at twelve days (Period 9), by which time fusion is normally complete. At 13 to 15 days (Periods 10–11) the fissure is unfused or irregularly fused in regions of variable location and extent. The occurrence of fissure fusion with concomitant loss of continuity between inner and outer epithelial layers is generally restricted to expanded anterior regions in 14–16 day (Periods 11–12) eyes. The presence of presumptive neural retina in the outer layer of the cup characterizes the mutant eye; and to varying degrees, in day 13–16 eyes, the presumptive neural retina (1) provides persistent continuity between the two cup layers, (2) forms both fused and unfused margins of the optic fissure, and (3) extends into an outer position of the optic cup. As early as 13 days (Period 10), nerve fibers are present in the outer layer of the cup, and by the last prenatal and first postnatal days (Period 12), ectopic nerve fiber bundles are widely distributed.
Ultrastructure of the supporting cells in the chemoreceptor areas of the tentacles of Pomatias elegans (Müller) (mollusca, prosobranchia) and the ommatophore of Helix pomatia L. (Mollusca, Pulmonata)
Authors: Wondrak Günter
Published: February 2005

The ultrastructure of the supporting cells in the chemoreceptor areas of the tentacles of Pomatias elegans and Helix pomatia is very similar. Complex apical structures are present, and the lateral plasma membrane exhibits three zones: (1) a zone of slight interdigitations; (2) a zone characterized by longitudinal plicae; (3) a zone of basal radiculae. The portions of the sensory cells located within the epithelial layer are accommodated in longitudinal grooves in the supporting cells. However, there are also differences. In Pomatias elegans the apical surface is differentiated into long microvilli that are sometimes dichotomously branched and invested by a surface coat along their entire length. Cytofilia and cilia of the sensory cells pass through this layer of microvilli and surface coat throughout its entire width. In Helix pomatia the supporting cells are somewhat smaller and the apical differentiation consists of candelabra‐like protrusions, which are usually three times dichotomously branched. The final branchings, corresponding to microvilli, are called terminal twigs. They are covered by a surface coat, which forms a feltwork. The cytofilia and cilia of the sensory cells that intertwine among the protrusions are confined to the space below the terminal twigs, where they compose the spongy layer.
Embryonic stages of Gastrotheca riobambae (fowler) during maternal incubation and comparison of development with that of other egg‐brooding hylid frogs
Authors: del Pino Eugenia M. , Escobar Bertha
Published: February 2005

A table of development (25 stages) for the period of incubation in the pouch was constructed for Gastrotheca riobambae; it can be used to stage embryos of other egg‐brooding hylids. Analysis of embryonic weights during incubation shows that the mother does not contribute nutrients, but gases and other factors are probably exchanged between mother and embryos.

According to species, incubation on the back of the mother is carried to the froglet or to the tadpole stages. Development in these hylids is characterized by specialized gills, the bell gills derived from the branchial arches. In some species, the bell gills derive from the first branchial arch and cover less than 50% of the embryo, while in others, the bell gills come from both branchial arches I and II and cover from less than 50% to 100% of the embryo. The most complex bell gills derive from the fusion of the two branchial arches.

The majority of egg‐brooding hylids live in tropical forests and carry development to the froglet stage. Tadpoles are produced by species of Flectonotus, Fritziana, and Gastrotheca. Tadpole‐producing species of Gastrotheca have the most complex reproductive adaptations among egg‐brooding hylids Acceleration and retardation in development seem to have played important roles in the evolution of these frogs. The evolutionary trend has been toward direct development, i.e., disappearance of the free‐living larval stages through maternal incubation, and later to a recovery of the free‐living tadpole stages in species of Gastrotheca with the most complex reproductive adaptations.
Morphological investigation into functions of the jaw symphysis in carnivorans
Authors: Scapino Robert
Published: February 2005

The hemimandibles in carnivorans may be united in various ways at the symphysis menti. The symphysis may contain a readily flexible joint that permits a moderate amount of independent movement of the hemimandibles. This type of symphyseal union is primitive for and widely distributed in extant carnivorans. In other carnivorans, the symphysis is patent but allows slight or essentially no independent movement of the hemimandibles. Finally, the hemimandibles may be rigidly united by synostosis of the symphysis. The morphology, movement and, insofar as possible, function of these types of symphyses are described.
The cardiac ventricles of a baleen whale (Balaenoptera acutorostrata: Minke whale) and a toothed whale (Hyperoodon ampullatus: Bottlenose whale)
Authors: Rowlatt Ursula
Published: February 2005

Fifteen minke whale (Balaenoptera acutorostrata: Mysticeti) and three bottlenose whale (Hyperoodon ampullatus: Odontoceti) hearts were obtained from Norway. Only the ventricular mass and the base of the great arteries were available for study. The shape of the heart, the double apex, the narrowness of the interventricular septum in the dorsiventral plane, the side‐to‐side position of the ventricles, the relative thickness of the wall of the right ventricle, and the heavy trabeculation agree with other, brief reports of whale heart morphology. Coronary artery tortuosity, which has been described in sperm whales by others, was found in the bottlenose but not in the minke whales. It is suggested that the shape of the heart is associated with depth and duration of dives and that the pattern of trabeculation may be related to the size of the animal.
Hormone dependent changes in the apical connective tissue during early stages of forelimb regeneration in the hypophysectomized newt, Notophthalmus viridescens
Authors: Hessler Arthur C. , Landesman Richard
Published: February 2005

When a newt is hypophysectomized prior to or at the time of forelimb amputation a dermal barrier eventually forms between the apical cap of epithelium and the underlying mesenchymal tissues, and the typical regeneration response is transformed to a wound–healing morphology. When hypophysectomized newts are injected on continuous alternate days beginning either at the time of amputation or following a fifteen‐day delay, with either growth hormone (GH) or prolactin in combination with thyroxine (PLT4), normal regeneration occurs. Our experiment was designed to examine critically the early changes occurring in apical connective tissue that had been allowed to form as a consequence of hypophysectomy prior to forelimb amputation. Adult newts were hypophysectomized and five days later both forelimbs were amputated distal to the elbow. Following a delay of eight days, to permit the formation of connective tissue beneath the apical epithelium, they were injected intraperitoneally on successive alternate days with GH or with PL in combination with T4 in the aquarium water. The apical connective tissue of the limb stumps underwent a progressive erosion and became discontinuous by day 4. The limb morphology of hypophysectomized newts receiving ACTH or PL or maintained in thyroxine was virtually identical to sham–injected hypophysectomized controls. It appears that an initial effect of GH or PLT4 therapy is to establish the epithelial–mesenchymal interface that previously has been suggested to be a requisite for the regenerative event.
Organization of the telencephalon in the channel catfish, Ictalurus punctatus
Authors: Bass Andrew H.
Published: February 2005

The cytoarchitectonics of the telencephalon of the channel catfish, Ictalurus punctatus, are described as a basis for experimental analysis of telencephalic afferents and efferents. The olfactory bulb comprises: (1) an outer layer of olfactory nerve fibers, (2) a glomerular layer, (3) an external cell layer, (4) an inner fiber layer, and (5) an internal cell layer. The telencephalic hemispheres comprise the areas ventralis and dorsalis telencephali. The area ventralis consists of: (1) a precommissural, periventricular zone including nucleus 'nother (Vn), the ventral nucleus (Vv), and the dorsal nucleus (Vd); (2) a precommissural, migrated zone of central (Vc) and lateral (VI) nuclei; (3) a supracommissural nucleus (Vs); (4) a caudal commissural zone of postcommissural (Vp) and intermediate (Vi) nuclei; and (5) a preoptic area (PP). The area dorsalis comprises: (1) medial (DM), (2) dorsal (Dd), (3) lateral [DL, containing dorsal (DLd), ventral (DLv), and posterior (DLp) regions], (4) posterior (DP), and (5) central (DC‐1, ‐2, ‐3) areas. Nucleus taeniae (NT) is transitional between areas dorsalis and ventralis.
Carbohydrates in the webs of Argiope spiders
Authors: Tillinghast Edward K. , Kavanagh Edward J. , Kolbjornsen Paul H.
Published: February 2005

Glycoproteins are present in the web of the orb‐weaving spiders Argiope trifasciata and Argiope aurantia. Periodic acid‐Schriff reactive glyco‐proteins are confined in large part, to the sticky spiral and sticky spiral‐radial junctions. Glycoproteins containing amino sugars appear associated with all fibers, especially the radial fibers. Enzymes may be used to remove glycoproteins selectively from the sticky spiral and stabilimentum.
Involvement of actin and Na+‐K+ ATPase in urine formation of the freshwater pulmonate Helisoma
Authors: Khan Hamidur R. , Saleuddin A. S. M.
Published: February 2005

The site and process of urine formation in the renopericardial system of Helisoma have been investigated. Osmotic pressure and protein content of hemolymph from the heart, pericardial fluid from the pericardial cavity, prourine from the kidney sac, and urine from the ureter have been determined. Osmotic pressure is equal in hemolymph, pericardial fluid, and prourine, but less in urine. Protein content is similar in hemolymph and pericardial fluid, but much less in prourine and urine. Hemoglobin molecules are present in hemolymph and pericardial fluid but not in prourine. It is suggested that in Helisoma the kidney sac is the site of prourine formation, and prourine is an ultrafiltrate of hemolymph. The kidney epithelial cells contain 6‐ to 7‐nm microfilaments which react with heavy meromyosin producing unidirectional arrowheads. Numerous actin filaments are present in the vicinity of the lateral cell membranes and basal processes. It is possible that the actin filaments regulate the extracellular spaces for prourine passage. It is postulated that the actin‐rich kidney epithelium may generate hydrostatic pressure for ultrafiltration. Na+‐K+ ATPase is located on the luminal side of the kidney epithelium, which may regulate intracellular fluid level of the kidney epithelial cells, and thereby regulate their cell volume. Thus Na+‐K+ ATPase may be involved in the regulation of extracellular spaces in kidney epithelial cells. The enzyme may participate in the production of hyposmotic urine.
Analysis of mesenchyme in the developing hind limb of Rana pipiens larvae with implications for neural development
Authors: Pollack Emanuel D. , Richmond Mary
Published: February 2005

Mesenchyme in the hind limbs of Rana pipiens tadpoles may serve as an important influence on the development of specific neural structures involved in limb innervation. Thus a histological quantification of mesenchyme was undertaken to identify landmark stages with respect to mesenchyme presence and neural events. Mesenchyme remained as a high percentage of the limb tissue until stage V (Taylor‐Kollros stages, '46), after which it declined dramatically until its virtual absence after stage XI. The volume of mesenchyme, however, was greatest at stages VIII–IX. Periods of high and low mesenchyme content were correlated in time with potential limb involvement in regulating limb innervation and motor neuron loss from the lateral motor columns. This provides additional evidence for developmental relationships between events of the limb and neural tissues.