bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of regional variation in the vertebral column of terrestrial salamanders
Authors: Worthington Richard D. , Wake David B.
Published: February 2005

Regional variation in the vertebral column of several species of salamanders (families Ambystomatidae, Salamandridae and Plethodontidae) is analyzed. Measurements of three dimensions, centrum length, prezygapophyseal width, and transverse process length, provide the data. Ontogenetic, interspecific, intergeneric and interfamilial patterns of positional variation are diagrammed and discussed. Distinctive patterns of variation characterize the families, genera, and to a lesser extent, the species. The patterns of ambystomatid salamanders are the most generalized, and probably reflect derivation from a primitive ancestral stock. The most specialized conditions occur in the fully terrestrial plethodontids, a group generally considered to be highly derived. Data such as those presented here will aid in the identification of fossils.

The patterns described have functional significance. For example, species which have an aquatic larval stage and which return to aquatic breeding sites have vertebrae which taper in length and width behind the pelvis. This is a feature associated with production of a traveling wave in the tail which is necessary for propulsion in water. Fully terrestrial species do not have a tapering column. In them, standing waves, such as occur in the trunk region of all species, typically occur in the tail. The caudal vertebrae of terrestrial species are rather uniform in dimensions for some distance, and the tail is cylindrical in form. Other functionally important features include the narrowing and shortening of some anterior vertebrae, associated with the development of a neck in some species with tongue feeding mechanisms. In contrast, species which use their heads as wedges during locomotion have broadened anterior vertebrae which serve as sites of origin for hypertrophied neck muscles.
Fine structure and differentiation of ascidian muscle. I. Differentiated caudal musculature of Distaplia occidentalis tadpoles
Authors: Cavey Michael J. , Cloney Richard A.
Published: February 2005

The structure of the caudal muscle in the tadpole larva of the compound ascidian Distaplia occidentalis has been investigated with light and electron microscopy. The two muscle bands are composed of about 1500 flattened cells arranged in longitudinal rows between the epidermis and the notochord. The muscle cells are mononucleate and contain numerous mitochondria, a small Golgi apparatus, lysosomes, proteid‐yolk inclusions, and large amounts of glycogen. The myofibrils and sarcoplasmic reticulum are confined to the peripheral sarcoplasm.

Myofibrils are discrete along most of their length but branch near the tapered ends of the muscle cell, producing a Felderstruktur. The myofibrils originate and terminate at specialized intercellular junctional complexes. These myomuscular junctions are normal to the primary axes of the myofibrils and resemble the intercalated disks of vertebrate cardiac muscle. The myofibrils insert at the myomuscular junction near the level of a Z‐line. Thin filaments (presumably actin) extend from the terminal Z‐line and make contact with the sarcolemma. These thin filaments frequently appear to be continuous with filaments in the extracellular junctional space, but other evidence suggests that the extracellular filaments are not myofilaments.

A T‐system is absent, but numerous peripheral couplings between the sarcolemma and cisternae of the sarcoplasmic reticulum (SR) are present on all cell surfaces. Cisternae coupled to the sarcolemma are continuous with transverse components of SR which encircle the myofibrils at each I‐band and H‐band. The transverse component over the I‐band consists of anastomosing tubules applied as a single layer to the surface of the myofibril. The transverse component over the H‐band is also composed of anastomosing tubules, but the myofibrils are invested by a double or triple layer. Two or three tubules of sarcoplasmic reticulum interconnect consecutive transverse components.

Each muscle band is surrounded by a thin external lamina. The external lamina does not parallel the irregular cell contours nor does it penetrate the extracellular space between cells. In contracted muscle, the sarcolemmata at the epidermal and notochordal boundaries indent to the level of each Z‐line, and peripheral couplings are located at the base of the indentations. The external lamina and basal lamina of the epidermis are displaced toward the indentations.

The location, function, and neuromuscular junctions of larval ascidian caudal muscle are similar to vertebrate somatic striated muscle. Other attributes, including the mononucleate condition, transverse myomuscular junctions, prolific gap junctions, active Golgi apparatus, and incomplete nervous innervation are characteristic of vertebrate cardiac muscle cells.
Development of electric organs of Gymnarchus niloticus (Fam. Gymnarchidae): I. Origin and histogenesis of electroplates
Authors: Srivastava C. B. L. , Szabo T.
Published: February 2005

The development of the electric organs of Gymnarchus niloticus has been studied and the origin and histogenesis of an electroplate worked out. A segmental origin of the electroplate is reported for the first time for this fish. Light has been thrown on many hitherto obscure phenomena, viz., growth of core girth, loss of transverse striations on the myofibrillar elements, differentiation of electroplate polarities, shortening in length of the electroplate etc. The transverse striations of the myofibrillar bundle of the electroplate primordium progressively disappear with development owing to splitting apart of the constituent myofilaments and consequent loss of their parallel order, and not to degeneration of the myofibrillar bundle. The excessive growth of the core girth of the electroplates is caused by the deposition of some kind of interfibrillar substance probably secreted by the peripheral cytoplasm.
The structure of the haemocytes of Calpodes ethlius (Lepidoptera)
Authors: Lai‐Fook Joan
Published: February 2005

The haemocytes of Calpodes ethlius are described with the light and electron microscopes. Five fine structurally distinct types are distinguishable. However only three of these, the granular haemocytes, sphaerule cells and oenocytoids can be positively identified using a series of histochemical stains on smears and on thick sections of araldite‐embedded material. The classification is based entirely on the structural features even though several suggestions concerning their function can be made from their fine structure. Intermediates having features of more than one cell type suggest developmental relationships.
Evidence concerning the morphogenesis of saccular receptors in the bullfrog (Rana catesbeiana)
Authors: Lewis E. R. , Li C. W.
Published: February 2005

A dichotomy of hair‐cell types has been found in the bullfrog sacculus, and considerable evidence supports the view that one type (“peripheral”) is transformed during macular growth to the other type (“central”). Between the periphery and the center of the macula, one finds a gradation of form from “peripheral” to “central” type. Occasionally in adults and more often in stage‐26 tadpoles one finds the presumably younger peripheral type of hair cell occurring well beyond the limits of the macula proper. The apparent morphogenic sequence for saccular hair cells is (1) development of a kinocillum on an endolymphatic epithelial cell, (2) gradual transformation of microvilli into stereocilia, (3) growth of the stereocilia and development of kinociliary bulb, (4) achievement of final size and form.
Some morphological and ultrastructural changes in the ependyma of the amputation stump during early regeneration of the tail in the lizard, Anolis carolinensis
Authors: Turner James E. , Singer Marcus
Published: February 2005

Light and electron microscope studies indicate that the old ependyma just proximal to the plane of amputation in early lizard tail regenerates shows a sequence of morphological changes which suggests that it as well as the new ependyma growing into the regenerate may play an active role in the initiation and maintenance of early tail regeneration.

The old ependyma close to the plane of amputation undergoes hypertrophy and/or hyperplasia causing a partial closure of the central canal and pseudostratification. Its nuclei shift from an original apical position to a basal one. The ependymal processes become more prominent and extend to the pia, a condition not found more rostrally. There is also a significant increase in the amount of Golgi substance and a moderate increase in the rough endoplasmic reticulum. These observations lead to the thought that these cellular changes may be an expression of enhanced secretion and other activities in the old and new ependyma just proximal or distal to the plane of amputation.
Morphology of the reproductive system of the armadillo. The spermatogonia
Authors: Nagy Frank , Edmonds Richard H.
Published: February 2005

Spermatogonia of the nine‐banded armadillo, Dasypus novemcinctus mexicanus, were studied morphologically using light and electron microscopy and examined histochemically using light microscopy. Immature flat type spermatogonia have ovoid or irregular nuclei with loosely condensed chromatin. Free ribosomes are abundant while profiles of rough endoplasmic reticulum are scarce. Smooth endoplasmic reticulum is a prominent feature occasionally taking an unusual cylindrical form. Mature spermatogonia exhibit rounder nuclei with greater degrees of chromatin clumping. Smooth endoplasmic reticulum is no longer prominent whereas profiles of rough endoplasmic reticulum are quite common. Occasional lysosomal configurations are found in mature spermatogonia.

The majority of spermatogonial cells exhibit weak to moderate reactivity when stained with the periodic acid‐Schiff (PAS) reaction. Certain cells in each tubular cross section stain vividly with this reaction and the PAS positivity is removable with salivary amylase. Because of nuclear characteristics, position of the cell immediately upon the basal lamina, intensity of the PAS reaction and the relative paucity of the vividly staining cells, it is suggested that they are members of the immature spermatogonial cell line, perhaps acting as stem cells. None of the several other histochemical procedures employed was capable of selectively demonstrating these cells.
Thecal vascularity in ovarian follicles of different size and rank in the lizard Anolis carolinensis
Authors: Gerrard Althea M. , Jones Richard E. , Roth Jan J.
Published: February 2005

Ovarian follicular histology of the lizard Anolis carolinensis was studied in relation to follicular size and rank. The structure of the Anolis follicular granulosa is similar to that described in other reptiles. Changes in the granulosa during follicular hypertrophy are also similar to those described in other species. Follicles of low rank in the linear size‐gradation exhibited atresia.

Counts were made of erythrocytes per millimeter of thecal tissue in crosssections of follicles of different size and rank. Follicles greater than 2.6 mm in diameter exhibited a marked increase in the number of thecal erythrocytes. Also, follicles of a similar diameter tended to possess a greater number of thecal erythrocytes the highter the rank in the linerar size‐gradation. These observations support the hypothesis that follicular selection involves appropriation of blood and blood‐borne hormones by larger follicles.
Fine structure of the gular gland of the free‐tailed bat Tadarida brasiliensis
Authors: Gutierrez Mercedes , Aoki Agustin
Published: February 2005

The gular gland of the bat Tadarida brasiliensis is a specialized sebaceous gland located in the skin of the suprasternal region of adult males. It consists of an aggregation of simple branched tubulo‐acinar gland units, the number of which varies seasonally. Each acinus is composed of densely packed sebaceous cells at various stages of differentiation. Acinar basal cells and cells of the epithelium of the ducts can differentiate into sebaceous cells. Two main changes appear in the cytoplasm concurrent with the sebaceous transformation: the differentiation of cytoplasmic organelles and the deposition of lipid material. The appearance of a different type of mitochondrion and the development of large numbers of ribosomes and polyribosomes can be recognized in the cytoplasm at an early stage of differentiation. Concomitant with the deposition of significant numbers of lipid droplets, the cells develop abundant agranular endoplasmic reticulum occurring mainly as scattered tubular cisternae. These at times form whorls surrounding lipid droplets. At later stages, the cisternae of the agranular endoplasmic reticulum often occur in crystalline arrays between secretory oil droplets. The roles of the different cytoplasmic organelles, especially in relation to the production of sebum, are discussed.
Tooth growth and replacement in Ctenolucius hujeta, a neotropical characoid fish
Authors: Lawson Ronald , Manly Brian F. J.
Published: February 2005

The predaceous neotropical characoid fish Ctenolucius has an essentially homodont dentition, the number of teeth increasing linearly with age. The basic manner of tooth replacement suggests that Ctenolucius is a primitive characoid. Tooth replacement continues throughout life and is similar to that of tetrapods, involving replacement waves which pass from the back to the front of the jaws. The waves containing the greatest number of teeth are found just anterior to the middle of the jaws. In the upper jaw the increase in the number of teeth is restricted to the anterior portion (premaxillary) whereas the number on the posterior part (maxillary) remains constant. In specimens measuring from 68–230 mm in standard length the posterior portion of the upper jaw doubles in length whereas the anterior portion triples. It is suggested that the area immediately anterior to the middle of the jaw, where replacement waves are longest, is where most of the increase in tooth numbers occurs.

During growth of the teeth the absolute height is always greater than the absolute width as the shape changes. The final shape of the recurved conical teeth is determined only in the last stages of tooth formation when the main axis of growth abruptly changes.
Physiology of feeding in miniature pigs
Authors: Herring Susan W. , Scapino Robert P.
Published: February 2005

The anatomy and physiology of feeding in miniature swine were studied, using gross dissection, electromyography, cinematography, and cineradiography.

Small particles are preferred for ingestion, and large items are usually broken down outside of the oral cavity. The particles are initially picked up with the lower lip and then retrieved by the tongue; the tongue very rarely leaves the oral cavity. Geniohyoid, mylohyoid and digastric are the most active muscles during food collection.

Mastication is fairly rapid (3 cycles/sec) and involves a transverse component which may be either medially or laterally directed. The direction of motion is generally reversed with every chew. Electromyography indicates that the transverse rotation is caused by a force couple consisting of protrusors (masseter, medial and lateral pterygoids) on one side and retrusors (zygomaticomandibularis and temporalis) on the other. The direction of the rotation is not necessarily related to the side containing the bolus. Mandibular depression is electromyographically biphasic. Concurrent tongue and hyoid movements complicate the interpretation of activity patterns in the oral floor.

Both masticated food and liquid are stored between the tongue and the soft palate and epiglottis before being swallowed. Swallowing involves very strong activity in all of the hyoid and tongue muscles and very low activity in the adductors. Liquid is taken in by suction rather than lapping.

Comparisons with other mammals are presented.
The ear and hearing in the frog, Rana pipiens
Authors: Wever Ernest Glen
Published: February 2005

Improved histological procedures have revealed in some detail the form and structure of auditory receptor organs in the frog. These organs, the papilla amphibiorum and papilla basilaris, are located in extensions of the saccular cavity, and lie in a path of vibratory fluid motion beginning at the columellar footplate and extending in a continuous circuit through the perilymph spaces and the round window back to the middle ear region.

These organs exhibit great uniformity, and for the amphibian papilla there is a high degree of complexity in the tectorial structures that overlay the ciliated ends of the hair cells. In both papillae a “sensing membrane,” which is a derivative of the tectorial body, lies in the path of fluid flow and aids in the stimulation process.

The mode of stimulation of the hair cells in the amphibian ear is peculiar, and in principle is the reverse of the familiar one of reptiles, birds, and mammals.
Cribriform plate of ethmoid, olfactory bulb and olfactory acuity in forty species of bats
Authors: Bhatnagar Kunwar P. , Kallen Frank C.
Published: February 2005

Relationships between the cribriform plate of the ethmoid, the olfactory bulb, and olfactory acuity were explored using material from 13 of the 17 bat families.

All megachiropteran cribriform plates were entirely perforated. In contrast, microchiropteran plates showed distinct perforated portions dorsally and nonperforated portions ventrally. The plates of frugivorous species had more foramina than those of insectivorous ones. Bats with mixed dietary habits were intermediate. Our data suggest that the Chilonycterinae were originally frugivorous, and have only secondarily reverted to an insectivorous diet.

Trend analyses show that wherever dietary preference appears to favor a more acute sense of smell, bulb diameter tends to be larger. In general, frugivorous bats tend to have bulbs exceeding 2 mm in diameter; insectivorous bats tend to have bulb diameters of 2 mm or less. The number of foramina in the plates and total cribriform plate area tends to increase as a function of bulb area, but the plate area the foramina occupied increases as a function of bulb volume. The ratio of the size of the bulb to the size of the cerebral hemisphere does not predict olfactory acuity in bats.
Morphology and histochemistry of the mast cells of snakes
Authors: Sottovia‐Filho Dagoberto
Published: February 2005

Mast cells were demonstrated in eight species of snakes, using special fixation techniques to prevent solubilization of cytoplasmic granules. Toluidine blue O and azure A were the major stains and observations were made under light microscope including cytophotometric analysis.

The mast cells of snakes were shown to be relatively small (7–11 μ in diameter) when compared to mast cells of a lizard (8–15 μ), dog and rat (9–15 μ).

Among the various organs examined, mast cells were particularly numerous in the mesentery, tongue, underneath the serosa of the digestive tract and in the heart, between muscle fibers and in the epicardium.

Although under the light microscope some snake mast cells seemed to be orthochromatically stained, when analysed by cytophotometry they were demonstrated to be actually metachromatic.

Snake mast cells granules were demonstrated to have an amphoteric behavior, since they were stained with both basic (toluidine blue O and azure A) and acid dyes (eosin and ponceau‐acid‐fuchsin).
Ultrastructure of the crayfish kidney—coelomosac, labyrinth, nephridial canal
Authors: Peterson Darryl R. , Loizzi Robert F.
Published: February 2005

Regions of the crayfish kidney were examined by electron microscopy. Coelsmosac cells are loosely bound together by desmosome‐like spot junctions, and connected to the basal lamina via characteristic pedicels. The cytoplasm contains numerous vesicles and vacuoles of various sizes and is often crowded with large, lysosome‐like granules or dense bodies. The morphology suggests a filtration mechanism with reabsorption of materials such as protein from the filtrate and secretion of other substances into the lumen.

The labyrinth is composed of cuboidal to columnar cells which possess a brush border, long and narrow intercellular spaces, basal plasmalemmal invaginations and typical cytoplasmic components. Two sub‐regions are distinguishable. The morphology of labyrinth I suggests that these cells move fluid isotonically across the epithelium. Labyrinth II, in addition to isotonic transport, appears to be more active in the endocytic uptake and intracellular digestion of large molecules such as protein.

The nephridial canal consists of cells which lack a brush border, but display extensive basal invaginations associated with elongated mitochondria. A proximal and distal region are cytologically distinguishable. Proximally, the cells are small and filled with mitochondria throughout. Scattered within the cytoplasm are vesicles, vacuoles, diffuse glycogen, free ribosomes, dense bodies and some rough endoplasmic reticulum. Distally, the cells are less compact, larger, and cuboidal to columnar in shape. The cytoplasm is similar to that of the proximal cells, but the basal invaginations are even larger and more extensive. The morphology of cells in both regions of the nephridial canal is highly suggestive of active solute reabsorption, probably occurring against an osmotic gradient.
The development of gill arches and gill blood vessels of the rainbow trout, Salmo gairdneri
Authors: Morgan Miriam
Published: February 2005

Gill development begins on the sixth day of incubation at 10°C and is complete by 31 days (hatching). Gill arches are formed by fusion and perforation of ectoderm and endoderm across the pharyngeal wall. A primary branchial artery forms within each arch and a second branchial artery forms as a branch from its ventral end. A series of filament loop vessels forms connecting the two arteries and when several are patent a unidirectional blood flow is established via afferent (second) branchial artery, filament loop vessels to efferent (primary) branchial artery. Part of the efferent branchial artery just above its junction with the afferent branchial artery constricts and occludes. It is suggested that this change in the pattern of blood flow is dependent on differences in resistance of the two branchial arteries. A later extension of the gill ventrally is thought not to be homologous with similar regions in elasmobranchs and Acipenser.
The vas deferens of the spider crab, Libinia emarginata
Authors: Hinsch Gertrude W. , Walker Muriel H.
Published: February 2005

Sperm enter the anterior vas deferens individually in the spider crab male. There they become surrounded by secretion products from the cells of the vas deferens, and are compartmentalized into spermatophores of varying size. The anterior vas deferens can be divided into three regions. The epithelium of the anterior vas deferens varies regionally from low to high columnar. The cytoplasm contains vast arrays of rough endoplasmic reticulum and Golgi complexes but few mitochondria. Intercellular spaces contain septate junctions, gap junctions and vesicles.

Once the spermatophores have been formed in the anterior vas deferens, they are moved posteriorly to the middle vas deferens where they are stored and surrounded by seminal fluids. The epithelial cells of the middle vas deferens contain large amounts of rough endoplasmic reticulum and Golgi complexes. Numerous micropinocytotic vesicles appear, forming at the cell surface and within the apical cytoplasm. Their suggested function is the resorption of secretion products of the anterior vas deferens which initiated compartmentalization of the spermatozoa into spermatophores.

The posterior vas deferens functions primarily as a storage center for spermatophores until they are released at the time of copulation. Seminal fluid surrounding the spermatophores is produced in this region as well as in the middle vas deferens. The cells of this region contain vast arrays of vesicular rough endoplasmic reticulum and Golgi complexes. The cells are multinucleate. Microtubules are numerous throughout the length of the cells and appear to insert on the plasma membrane.
The spermatozoon of arthropoda. XXIV. Sperm metamorphosis in the diplopod Polyxenus
Authors: Baccetti B. , Dallai R. , Bernini F. , Mazzini M.
Published: February 2005

The authors describe the spermiogenesis of Polyxenus lagurus, a diplopod, in the male genital ducts and the transformations the spermatozoon successively undergoes in the spermatheca.

The spermatozoon in the male genital ducts looks like a little barrel devoid of centriole and of any kind of rudimentary flagellum whatever. The organelles are markedly modified; cross sections present an elongated, flattened nucleus, an X‐shaped body running parallel to it on the opposite side and two longitudinal mitochondrial strips interposed between them. The rest of this barrel‐shaped spermatozoon is filled with peculiar Golgi formations, the spongy chambers, which open outwards through little vents.

In the spermatheca the spermatozoon is quite different: it is shaped like a long ribbon. The basic structure of the spermatozoon is formed by the double folding of part of the cortical layer of the barrel‐shaped spermatozoon. On the central part of this endo‐skeleton are longitudinally ranged the nucleus and the acrosome flanked on both sides by a thread of mitochondria. Even in this phase the sperm has no flagellum.
Sensory innervation monitoring movement and position in the mandibular stylets of the aphid, Brevicoryne brassicae
Authors: Wensler Rita J. D.
Published: February 2005

The sensory innervation of the mandibular stylets of the aphid Brevicoryne brassicae (L.) has been examined by electron microscopy. Two groups of sensory neurones are present in the mandible. Each has two neurones, one with a short dendrite extending into the base of the mandible and ending in the base and another with a long microtubular process which extends 500 m̈ down to the distal tip of the mandible. The two neurones are enclosed by an ensheathing cell comparable to the trichogen cell enveloping the group of neurones innervating pegs and hairs. This ensheathing cell is supported by extensive electron‐dense filaments to form a scolopale and is embedded in the mass of stylet‐forming cells at the base of the mandible. The inner segments of the dendrites are anchored to the ensheathing cell by desmosome junctions. Desmosome junctions also bind the microtubular outer segments of the short and long dendrite to each other. There is no evidence of a dendritic sheath enclosing the distal portion of the short dendrite which ends while still in the extracellular space within the ensheathing cell. The microtubular process of the long dendrite extends down the lumen of the mandible enclosed by a close‐fitting extracellular sheath which penetrates and is attached to the cuticular wall of the mandible tip. Distally this sheath is thickened on one side. Deflection of the mandible would therefore deform the dendritic membrane asymmetrically because the thin walls of the sheath would bend more than the thick walls. This would exert an unequal mechanical strain on the dendritic membrane which could result in depolarization in response to deflection in a particular direction. The arrangement of the dendrites and their sheaths within the mandible is such that deflection to the right would distort one dendrite in the same way as deflection to the left would distort the other.
The hemocytes of a scorpion Palamnaeus swammerdami
Authors: Ravindranath M. H.
Published: February 2005

Some of the cytological characteristics of the hemocytes of the scorpion, Palamnaeus swammerdami, were studied. The morphological features of the arachnid hemocytes were observed to be similar to those of hemocytes of insects, millipedes and isopods. Jones' system of hemocyte classification was extended to the arachnid hemocytes. The six classes of hemocytes indentified in the scorpion correspond to prohemocytes, plasmatocytes, granular hemoocytes, cystocytes, spherule cells and adipohemocytes of insects. A cell type comparable to oenocytoids of insects and crustaceans is absent. The prohemocytes can be subdivided into four categories that probably represent the precursors of the major cell types. The cytological characteristics of the major cell classes and the occurrence of the miniatures of some of these major cell types support the concept of Jones (62) that these cell types might have different cell lineages and might not be capable of transforming into one another. Some of the prohemocytes, plasmatocytes and granular hemocytes were amoeboid. The nature of the granules and the vacuoles of plasmatocytes and granular hemocytes were compared with the granules and vacuoles of corresponding hemocytes of other arthropods. Cystocytes did not bring about any visible coagulation similar to their counterparts in millipedes and crustaceans. Plasmatocytes, granular hemocytes and spherule cells were observed to occur in conglomerates. The cell types noted in the present study were compared with the hemocytes of other arachnids.
The morphology of the fourth abdominal ganglion of the hermit crab: A light microscope study
Authors: Chapple William D. , Hearney Elaine Schmidt
Published: February 2005

The hermit crab, Pagurus pollicarus, has the same organization in its fourth abdominal ganglion as its macruran relatives in spite of the reduction in abdominal muscles, sensory receptors, and appendages. Connective axons are grouped into discrete bundles between which five groups of commissural fibers run to connect left and right sides. The neurites of ventral cell bodies run dorsally in characteristic groups between the connective bundles. The hermit crab fourth ganglion has two thirds as many cells as the crayfish and is laterally compressed. This reduction appears related to the reduction in the sizes of the ganglionic roots. The ventral fine fibered neuropil is larger on the left than the right side reflecting the loss of pleopods on the right side. The basic organization of decapod abdominal ganglia appears to permit considerable integrative flexibility within a relatively conservative morphological framework.
Ultrastructural studies of regenerating spines of the sea urchin Strongylocentrotus purpuratus. II. Cell types with spherules
Authors: Heatfield Barry M. , Travis Dorothy F.
Published: February 2005

The fine structure of spherulecytes, cell types with large, intracellular membrane‐bound vacuoles termed spherules, was investigated in regenerating tips of spines of the sea urchin Strongylocentrotus purpuratus. Two categories of cell types were observed: red spherulecytes and colorless spherulecytes. Red spherulecytes were represented by a single cell type, the eleocyte, while colorless spherulecytes consisted of three morphologically distinct cell types termed morula cells, granulocytes, and vacuolecytes. Eleocytes and morula cells were distributed in both the epidermis and dermis, while granulocytes and vacuolecytes were present only in the dermis. After processing for light and electron microscopy, the spherules of eleocytes typically appeared empty, having lost their content of the red pigment, echinochrome. In contrast, the spherules of morula cells, granulocytes, and vacuolecytes enclosed a variety of granular and other material.

The cell types reported in this paper resembled, to various degrees, spherulecytes in the coelomic fluid of echinoids described by other investigators.
The ecdysial gland of the spider crab, Libinia emarginata (L). I. Ultrastructure of the gland in the male
Authors: Hinsch Gertrude W. , Hajj Hameed Al
Published: February 2005

The ecdysial glands of mature male Libinia emarginata are pale, yellowish organs composed of lobes of epithelial cells having oval nuclei which are often eccentric and which have one or two nucleoli containing amorphous granular material and coarse strands. The plasma membrane bordering the basal lamina consists of invaginations containing microtubules which may serve to increase the surface area for metabolic exchange. Masses of smooth endoplasmic reticulum and associated vesicles are scattered throughout the cytoplasm. Two or more vacuoles may coalesce. Larger vesicles lie close to the cell surface. Numerous mitochondria with tubular cristae surround the nucleus and frequently are associated with SER. A few Golgi complexes consisting of flattened sacs, cisternae or vesicles, lipid droplets and free ribosomes were seen. Adjacent plasma membranes may be in close apposition or separated by a space filled with vesicles, granules, or blood or supporting cells. This type of ultrastructure is associated with steroid‐secreting cells.
Mitochondrial changes in flight muscles of normal and flightless Drosophila melanogaster with age
Authors: Sohal R. S.
Published: February 2005

Fine structural changes in mitochondrial morphology pertaining to size, number and growth were examined in flight muscles of normal and experimentally dewinged male Drosphila melanogaster ranging up to 26 days of age. In the normal winged flies, the number of mitochondria decreases during the first week of adult life whereas the size of individual mitochondrial profile increases significantly. Changes in mitochondrial size and number are due to the fusion of mitochondria. Fused mitochondria are extremely large in size and irregular in shape. In 26‐day old normal flies, the number of mitochondria increases while the mitochondrial size is reduced indicating mitochondrial division. In comparison to the normal flies, dewinged flies exhibit a similar degree of mitochondrial fusion and growth during the first week of life. However, the extent of mitochondrial fission in 26‐day old dewinged flies is greater than in the normal flies of this age. Structural mechanisms of mitochondrial fusion and fission are described. The objective of this study was to examine the relative effects of age and flight activity on the mitochondria.
Functional morphology of the neck organ in Artemia salina nauplii
Authors: Hootman Seth R. , Conte Frank P.
Published: February 2005

Fine structure of the ion transporting epithelium of the neck organ in the brine shrimp (Artemia salina) nauplius is described. The neck organ is a dome‐like gland situated atop the cephalothorax of the larva and is composed of 50 to 60 cuboidal epithelial cells. These cells possess many of the characteristics of salt‐secretory cells from other tissues. They contain many mitochondria and exhibit a high degree of plasma membrane elaboration. This membrane amplification takes two forms; the apical plasmalemma is infolded into irregular loops, while the basal and lateral membranes penetrate the cytoplasm in the form of branching sinusoids. The labyrinth of tubular reticulum thus formed fills most of the cell volume. Mitochondria in the labyrinth are often in intimate contact with these tubular membranes and regular arrays of parallel mitochondria with constricted intervening sinusoids are often observed. Other organelles including Golgi complexes, multivesicular bodies, and rough endoplasmic reticulum are also numerous, particularly in the narrow rim of cytoplasm which lies between the apical infolds and the labyrinth. Yolk platelets and glycogen fields are conspicuous in the basal perinuclear regions of the cells.
The cardiac muscle in the pulmonary vein of the rat: A morphological and electrophysiological study
Authors: de Almeida Oslei Paes , Böhm György Miklös , Carvalho Marilene de Paula , de Carvalho Antonio Paes
Published: February 2005

The pulmonary veins of albino Wistar rats were studied by means of light and electron microscopy. The media of larger veins consists of cardiac muscle fibers which extend until the vessels attain about 100 μ in diameter. This coat consists of external longitudinal fibers and internal circular fibers. The vasa vasorum are well developed and the capillaries show pseudofenestrations. The numerous adrenergic and cholinergic nerve endings do not form typical motor end‐plates as seen in skeletal muscles. The ultrastructure of these media muscle fibers is similar to that of rat hearts. The smooth muscle layer of larger pulmonary veins is not continuous as it is in smaller veins where it forms cushions. Comparisons of albino rats and other rodents reveal striking differences.

Action potential shape and propagation velocity (0.5–1.2 m/s) along the myocardial coat of the pulmonary vein were similar to those observed in the left atrium and so was their sensitivity to locally applied acetylcholine. The physiological direction of propagation in rat pulmonary veins is toward the lung. This finding lends support to the hypothesis of a rhythmic, valve‐like action of the striated musculature of the pulmonary venous wall during the systole and a possible role in the capacitance of the pulmonary circulation.
Functional anatomy and sexual dimorphism of the cephalic clasper in the pacific ratfish (Chimaera collei)
Authors: Raikow Robert J. , Swierczewski Edward V.
Published: February 2005

The cephalic clasper of the male Chimaera collei is a cartilaginous rod equipped with denticles and presumably used to grasp the female during copulation. It is attached to the skull by ligaments but there is no joint cavity or articular surface. It has no intrinsic muscles, its movements being provided by attachments to muscles of the lower jaw and labial cartilages. The cephalic clasper is apparently elevated by a branch of the preorbitalis muscle, whose main function is to elevate the lower jaw. It appears to be forcefully depressed during copulation by M. levator anguli oris, whose primary function is to move the labial cartilages. When not in use, the cephalic clasper is held passively depressed by an elastic tendon from M. preorbitalis. In the female the cephalic clasper is represented by an apparently functionless rudiment.
The aquiferous systems of three marine demospongiae
Authors: Reiswig Henry M.
Published: February 2005

The aquiferous systems of three common, coastal, marine Demospongiae, Halichondria panicea (Pallas), Haliclona permollis (Bowerbank) and Microciona Prolifera (Ellis and Solander), are analyzed by measurements of cross‐sectional areas of conducting elements. The patterns in demosponges of extremely different organizational morphologies are found to be quantitatively similar. The porocyte nature of the ostia is established for all three species. Choanocyte chamber densities range from 1 to 1.8 × 107 chambers ml−1 with 57 to 95 choanocytes per chamber (means). Cross‐sectional area of the intervillar space of the choanocyte collars is calculated to be 12 to 56 times the lateral surface area of the specimen. Velocities of water movement through specific elements of the aquiferous system are calculated from cross‐sectional area data and measured oscular flow of Haliclona permollis. The calculated Reynolds numbers lie below the critical value and fluid flow is thus considered laminar throughout the aquiferous systems of these sponges.
Electromyography and mechanics of mastication in the albino rat
Authors: Weijs W. A. , Dantuma R.
Published: February 2005

The masticatory apparatus in the albino rat was studied by means of electromyography and subsequent estimation of muscular forces.

The activity patterns of the trigeminal and suprahyoid musculature and the mandibular movements were recorded simultaneously during feeding. The relative forces of the individual muscles in the different stages of chewing cycles and biting were estimated on the basis of their physiological cross sections and their activity levels, as measured from integrated electromyograms. Workinglines and moment arms of these muscles were determined for different jaw positions.

In the anteriorly directed masticatory grinding stroke the resultants of the muscle forces at each side are identical; they direct anteriorly, dorsally and slightly lingually and pass along the lateral side of the second molar. Almost the entire muscular resultant force is transmitted to the molars while the temporo‐mandibular joint remains unloaded. A small transverse force, produced by the tense symphyseal cruciate ligaments balances the couple of muscle resultant and molar reaction force in the transverse plane. After each grinding stroke the mandible is repositioned for the next stroke by the overlapping actions of three muscle groups: the pterygoids and suprahyoids produce depression and forward shift, the suprahyoids and temporal backward shift and elevation of the mandible while the subsequent co‐operation of the temporal and masseter causes final closure of the mouth and starting of the forward grinding movement. All muscles act in a bilaterally symmetrical fashion.

The pterygoids contract more strongly, the masseter more weakly during biting than during chewing. The wide gape shifts the resultant of the muscle forces more vertically and more posteriorly. The joint then becomes strongly loaded because the reaction forces are applied far anteriorly on the incisors. The characteristic angle between the almost horizontal biting force and the surface of the food pellet indicates that the lower incisors produce a chisel‐like action.

Tooth structure reflects chewing and biting forces. The transverse molar lamellae lie about parallel to the chewing forces whereas perpendicular loading of the occlusal surfaces is achieved by their inclination in the transverse plane. The incisors are loaded approximately parallel to their longitudinal axis, placement that avoids bending forces during biting. It is suggested that a predominantly protrusive musculature favors the effective force transmission to the lower incisors, required for gnawing. By grinding food across transversely oriented molar ridges the protrusive components of the muscles would be utilized best. From the relative weights of the masticatory muscles and their topographical relations with joints, molars and incisors it may be concluded that the masticatory apparatus is a construction adapted to optimal transmission of force from muscles to teeth.
Cytophysiological basis of disruptive pigmentary patterns in the leopard frog Rana pipiens. II. Wild type and mutant cell‐specific patterns,
Authors: Smith‐Gill Sandra J.
Published: February 2005

A new pattern index, Ip, is introduced and used to compare patterns of wild type, burnsi, and kandiyohi chromatophores in the leopard frog, Rana pipiens. Wild type chromatophores are hyperdispersed over distances within cellular contact, and it is concluded that this hyperdispersion results from contact‐mediated negative interactions. The hyperdispersion is less strong in spot cells than interspot, and extends over larger areas in burnsi than in wild type epidermis. Over areas greater than chromatophore size, patterns are either random or clumped. Patterning of kandiyohi melanophores is clumped into aggregates small enough to be within the range of cellular contact, suggesting a lack of contact inhibition among these cells. The possible roles of cellular properties and the extracellular environment in pattern determination are discussed.
The motor units of cat medial gastrocnemius: Electrical and mechanical properties as a function of muscle length
Authors: Stephens John A. , Reinking Robert M. , Stuart Douglas G.
Published: February 2005

The effects of changing muscle length on the mechanical properties of 89 motor units from adult cat medial gastrocnemius have been studied in eight experiments.

Few differences were found between the effects of length on tetanic tension, twitch tension, twitch‐tetanus ratio, twitch contraction time, twitch half relaxation time, rate of force development and electrical activity for fast contracting (twitch contraction time ⩽ 45 msec) and slowly contracting ( > 45 msec) units. Those differences that did appear did not persist when these two groups were matched by tetanic tension. It is concluded that the biophysical mechanisms responsible for the changes in mechanical and electrical properties with length must be similar for fast and slow twitch units and not related to potential differences in their muscle fiber type.

The effects of changing muscle length on the mechanical properties of the eight whole muscles suggest that changes in force output with length are of minor importance during normal movements as the muscle is found to be electrically active over a relatively narrow range of lengths close to the optimum length for tetanus of the whole muscle. The very shortest muscle lengths at which there is only minimal force development are not used in natural movements, while the declining limb of the length tension curve is at muscle lengths beyond the maximum in situ length.
Sensilla on the antennal flagellum of the sawyer beetles Monochamus notatus (Drury) and Monochamus scutellatus (Say) (Coleoptera: Cerambycidae)
Authors: Dyer Lucy J. , Seabrook W. D.
Published: February 2005

The antennae of the sawyer beetles Monochamus notatus and M. scutellatus were examined with the light and scanning electron microscopes to determine the types, number, distribution and innervation of the sense organs. Nine types of sensilla are described. Both short, thin‐walled pegs (sensilla basiconica) and reversely curved thick‐walled hairs (sensilla trichodea) are chemoreceptors. There are three types of long, thick‐walled hairs (sensilla chaetica) which may be mechanoreceptors. One of these is modified in males to form unique snail‐shaped pegs. A few dome‐shaped organs, probably campaniform sensilla, were found.

In addition to sense organs, many glands occur in association with the sensilla, and the antennae are well supplied with dermal glands connected by canals to small pores on the surface.
The microscopic anatomy of epidermal glands in two species of gekkonine lizards, with some observations on testicular activity
Authors: Chiu K. W. , Maderson P. F. A.
Published: February 2005

The gross and microscopic anatomy of epidermal glands has been studied in laboratory maintained tokays (Gekko gecko), and house geckos (Hemidactylus bowringii) captured from the wild throughout the year. Annual testicular activity in the house gecko has also been studied. While no significant differences in glandular development at various times have been observed in G. gecko, there are clear‐cut annual cycle in H. bowringii. The evolution of epidermal glands in gekkonid lizards is reviewed; the cellular dynamics of β‐glands are compared with those of unspecialized epidermis; the possibility that gekkonine epidermal glands respond to quantitative variation in circulating testosterone titers is discussed.
Development of the head skeleton and pectoral girdle in Esox
Authors: Jollie Malcolm
Published: February 2005

A consideration of head development in two species of Esox, lucius and americanus (ssp. vermiculatus) representing the two subgenera Esox and Kenozoa respectively, focused on the significance of the variations of the latero‐sensory canal system, its associated bones, and other skeletal elements. In living forms only aspects of “regression” or specialization can be studied. Canals tend to be reduced to pit lines first at their termini but can be broken in their course. Pit lines range from nearly canals to surface structures, or even fail to develop. The number of neuromasts varies. Canal bones develop from two centers: neuromast related and deeper membranous centers which may have no relationship to neuromasts. Tooth‐bearing and non‐canal‐related dermal bones have only membranous (original) centers. The number of neuromasts associated with a bone usually does not affect its development or form. In the case of the circumorbital bones, the extrascapulars, and the nasal, a one to one relationship has developed by regression – towards the development of the latero‐sensory component only. The idea that reductions in bone number are commonly traceable to fusion is rejected although examples of fusion are known. Most bones that disappear are simply lost (no blastema or other evidence of their presence seen in development). The relationship between dermal bone and chondral bone is examined and there is evidence of the former giving rise to the latter. The ontogenic order of appearances shows a feeding (functional) correlation.