bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns of regional variation in the vertebral column of terrestrial salamanders
Authors: Worthington Richard D. , Wake David B. 
Published: February 2005

AbstractRegional 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractLight 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

AbstractSpermatogonia 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

AbstractOvarian 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractImproved 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

AbstractRelationships 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

AbstractMast 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

AbstractRegions 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

AbstractGill 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.