bluuebunny/crossref_metadata_2025 huggingface dataset:
The development of the septum primum relative to atrial septation in the mouse heart
Authors: Dalgleish Arthur E.
Published: February 2005

The septum primum in the mouse originates as a thickened primordium with a straight rather than a sickle‐shaped ventral border. It is covered on its ventral border by anterior cushion material which is continuous over the roof of the atrium with the principal anterior cushion mass.

A process of cavitation thins the septum primum and precedes actual fenestration. This process shifts the membranous septum to the left thereby providing room for the septum secundum to overlap on the right side. The septum primum cannot contact the posterior cushion until closure of the sinus venosus gutter which is described. The closure of the interatrial foramen, later the foramen primum, is accomplished by cell growth of the anterior cushion material.

The ventral thick border of the septum primum contributes to the ventral limbus and the caudal thickened boundary of the fossa ovalis with some contribution from the left venous valve. These boundaries as well as the membranous portion of the interatrial septum are derived from the same primordium, namely the septum primum.
Salivary gland development in the blowfly, Calliphora erythrocephala
Authors: Berridge Michael J. , Gupta Brij L. , Oschman James L. , Wall Betty J.
Published: February 2005

The salivary gland of adult Calliphora erythrocephala is a tubular structure composed of secretory, reabsorptive, and duct regions. Development of these structures has been followed during the six days of larval and ten days of pupal growth. Two small groups of imaginal cells located at the junction between larval gland and duct give rise to the adult gland. These presumptive adult cells divide during all larval stages and appear to be functional components of the larval gland. Shortly after pupation, the larval gland breaks down and the imaginal cells proliferate rapidly, forming sequentially the duct, reabsorptive and secretory regions. Proliferating regions of the developing gland are frequently encrusted with haemocytes. As it elongates the gland establishes intimate contacts first with the basement membrane of the degenerating larval gland, later with an epithelial layer surrounding the main dorsal tracheal trunks, and then with the gut. Cell division continues until about five days after pupation, bu t the gland is unable to secrete fluid in response to 5‐hydroxytryptamine stimulation until two hours after the adult fly emerges. The Golgi complex appears to be involved in forming the highly folded membranes of the canaliculi in the secretory region.

Presumptive adult salivary gland cells appear to increase in number logarithmically from the time of hatching of the larva until five days after pupation. This contrasts with the development of classical imaginal discs, in which cell division ceases prior to pupation.
Structural changes occurring during transformation of the labial gland cells to their adult form, in Manduca sexta
Authors: Hakim Raziel S.
Published: February 2005

The labial gland of the adult sphingid moth, Manduca sexta, is composed of five distinct regions, each made of a single cellular type. Four of these regions are derivatives of the single specialized cellular population that makes up the caterpillar labial duct.

Both the larval labial duct and its derivatives are large, polyploid cells with pleiomorphic nuclei. There is a definite cellular continuity between the larval and adult forms of these cells throughout metamorphosis; no mitoses or cell deaths are seen to occur in the gland during transformation.

Cytological studies indicate that in the process of cell transformation the ducts first “dedifferentiate,” elongate, then redifferentiate. Intermediates in this process have well defined structures which should make this system useful in studying covert events in the transformation process.
The pectoral anatomy of selected Ostariophysi. II. The Cypriniformes and siluriformes
Authors: Brousseau Raymond Allan
Published: February 2005

The pectoral myology and osteology of the cyprinoids Notemigonus crysoleucas, the golden shiner, and Catostomus commersonnii, the common white sucker, resemble those of generalized, lower teleosts in structure and function, except in features related to the manipulation of the massive fifth ceratobranchial of cyprinoids by muscles attaching on the girdle. Catostomus is more specialized in having unique intercostal muscles to the girdle, complex subclavian arteries and lack of a superficial trapezius muscle. The bony pectoral anatomy of the siluriform, Ictalurus nebulosus, the brown bullhead, is highly specialized in relation to the presence and locking of the massive pectoral spine which is formed of fused dorsal and ventral propterygial rays; there is consolidation of the girdle through fusion of bones, presence of unique stabilizing bony structures, firm symphyseal union of bilateral girdles and the presence of friction‐surfaces of girdle and spine for locking. The movements of the spine are specialized in the greater guidance offered by the girdle. Myological specializations are related mainly to ventral appendicular muscles which lock the spine. The nervous and arterial systems are generalized.
Scanning microscopy of collagen in the basement lamella of normal and regenerating frog tadpoles
Authors: Overton Jane
Published: February 2005

The arrangement of collagen fibers over the body surface in the basement lamella of Pseudaeris and Xenopus tadpoles is described. It can be viewed by scanning microscopy after removal of epidermis and basal lamina by trypsin treatment of alcohol fixed tissue. The orthogonal array is modified in regions where fiber direction changes extensively such as the base of the ventral fin or the posterior part of the head. In these regions “exceptional points” in the orthogonal pattern occur, as described by Rosin (1946). The pattern is bilaterally symmetrical. In the region of the nasal opening the orthogonal pattern is replaced by a mat of randomly oriented fibers. In tail regeneration the wound area is marked by aberrant disposition of collagen anteriorly then a mat of randomly disposed fibers followed posteriorly with a sharp transition to the orthogonal pattern of the regenerate. No fiber terminations could be seen in normal or regenerating regions of the lamella.
Semicircular canal radii of curvature (R) in cat, guinea pig and man
Authors: Curthoys I. S. , Blanks R. H. I. , Markham C. H.
Published: February 2005

The radii of curvature (R) of the horizontal (Rh), anterior (Ra) and posterior (Rp) semicircular canals were measured by a new technique (called ROTA) for cat, guinea pig and man. For each canal, data points from the ossecus canal were rotated and plotted by computer such that the plane of the sheet of computer plot corresponded to the plane best fitting that canal. The radius of each osseous canal was determined and where necessary, the radius of the are of data points was corrected for thickness of the absent tissue. For cat, guinea pig and man there are differences in R between canals within a labyrinth suggesting that if other things are equal there could be differences in the average mechanical sensitivity of the canals, which is consistent with physiological recordings from primary vestibular neurons in the cat, The Rs determined by ROTA are compared with Rs determined by conventional histological means.
Anatomy and histology of the alimentary tract of the desert millipede Orthoporus ornatus (Girard) (Diplopoda: Spirostreptidae)
Authors: Nunez F. S. , Crawford C. S.
Published: February 2005

The alimentary tract of the desert millipede Orthoporus ornatus is essentially a straight tube consisting of a histologically distinct foregut, midgut, pylorus, hindgut, and rectum. Common to each region, but often different in regional appearance, are an outer sheath layer, longitudinal and circular muscle layers, a basement membrane, and an inner epithelial layer. Foregut and midgut lumina are lined by a cuticular intima, while a peritrophic membrane occurs in the midgut lumen.

Gut structure is considered in the context of the known feeding habits and digestive efficiency of this long‐lived, seasonally restricted detritivore.
Ca+2‐accumulating components in developing skeletal muscle
Authors: Smalls Charley M. , Goode Dennis
Published: February 2005

This ultrastructural study on the localization of Ca+2 in developing skeletal muscle indicates that the formation of calcium‐accumulating components begins during embryonic development. Both oxalate and pyroantimonate techniques are used to localize Ca+2 in distinct cellular components of chick pectoral and sartorius muscles. Two major sites for Ca+2 accumulation are present in ultrathin sections of embryonic and post‐embryonic muscles: the terminal cisternae of the sarcoplasmic reticulum and specific lines in the I‐bands. Calcium oxalate‐accumulating vesicles are present in the smallest recognizable myotubes at the twelfth day of incubation, but calcium‐accumulating components are not seen at myofibrillar I‐band sites until the fourteenth to seventeenth days of incubation. The fact that myofibrils first form and later in development accumulate a Ca+2‐binding component suggests that this Ca+2‐binding component is not necessary for the formation of myofibrils, but is added to myofibrils before hatching to serve a probable regulatory role in contraction.
Sense organs on the antennal flagellum of psocids (Insecta, Psocoptera)
Authors: Slifer Eleanor H. , Sekhon Sant S.
Published: February 2005

The sense organs on the antennal flagella of five species of winged psocids belonging to two families of Psocoptera, Psocidae and Leptopsocidae, have been examined. All agree in possessing tactile hairs, thick‐walled chemoreceptors and long, porous chemoreceptors. Thin‐walled chemoreceptors were identified in all species except Metylophorous novaescotiae. Coeloconic chemoreceptors were present in all species except Echmepteryx hageni. Campaniform sense organs were found only in Metylophorus novaescotiae and Psocus leidyi.
Mechanics of the syrinx in Gallus gallus. II. Electromyographic studies of Ad Libitum vocalizations
Authors: Gaunt Abbot S. , Gaunt Sandra L. L.
Published: February 2005

Records of electrical activity in the tracheal muscles of domestic chickens were obtained for a variety of ad libitum vocalizations. Primary attention was given to an analysis of events during the most complex call, crowing.

Three pairs of muscles, Mm. tracheohyoideus, tracheolateralis, and sternotrachealis, can affect the configuration of a chicken's syrinx. The firing patterns of the three muscle pairs are related to their different abilities to affect the tension of the syringeal membranes. The influence of M. tracheohyoideus is most indirect and imprecise, and its role the least clearly defined. It appears to adjust the position of the trachea so that the syrinx is isolated from unpredictable and/or undesirable consequences of nuchal position and tracheal elasticity, and also helps draw the glottis caudad, thereby deepening the pharyngeal chamber. The other two muscles interact to control the tension of the vocal membranes. M. sternotrachealis relaxes the membranes by drawing the drum of the trachea caudad, or, via the syringeal ligament, by rotating the pessulus cranioventrad, or both. M. tracheolateralis tenses the membranes and/or prevents caudal movement of the origin of M. sternotrachealis, a necessity if the syringeal ligament is to rotate the pessulus.

Vocalization depends on both syringeal configuration and appropriate air flow. Hence, tracheal muscles, syrinx, air sacs, and ventilatory muscles cooperate to form a vocal system. Cooperation elicits a surprising degree of redundancy. At least one call, a high pitched wail, may be produced by two very different techniques.
Chromatin diminution in early embryogenesis of Ascaris lumbricoides L. var. suum
Authors: Goldstein Paul
Published: February 2005

The occurrence of chromatin diminution in early Ascaris lumbricoides L. embryos has been studied in detail, and it is shown that it is possible to preselect three characteristic types of mitoses: pre‐diminution, diminution, and post‐diminution mitosis. The first three embryonic mitotic divisions are of the pre‐diminution type. Chromatin diminution occurs after the third mitosis, but there is a variation from embryo to embryo as to whether or not chromosomal diminution occurs during the fourth, fifth, and six divisions. However, the seventh embryonic division, which gives rise to an eight‐cell embryo, always exhibits chromatin diminution. Subsequent mitoses of somatic cells already in the diminished state are of the post‐diminution type of mitosis.
A new ganglion in male Moniliformis moniliformis (Acanthocephala)
Authors: Dunagan T. T. , Miller Donald M.
Published: February 2005

A new ganglion identified as the bursal ganglion is described from male Moniliformis moniliformis. This ganglion is located adjacent to the pseudocoel and longitudinal muscle fibers and medial to the dorsal lacunar canal about 1 mm from the posterior end of males with non‐everted bursa The ganglion consists of four large club‐shaped cells with single nuclei and bipolar neurons.

The ganglion cells are paired with one neuron from each cell innervating the opposite side of the worm.
Efferent connections of the striatum in Tupinambis nigropunctatus
Authors: Hoogland P. V.
Published: February 2005

The striatum of the lizard Tupinambis nigropunctatus lies in the lateral wall of the telencephalon and consists of two major subdivisions: the dorsal striatum and the ventral striatum.

Electrolytic lesions were placed in all parts of the striatal complex and in adjacent areas and the subsequent anterograde degeneration was studied using the Nauta‐Gygax and Fink‐Heimer techniques. Lesions in the dorsal striatum cause terminal degeneration in the ventral striatum both ipsi‐ and contralaterally. In addition, projections have been found to the lateral amygdaloid nucleus and to parts of the dorsal striatum not affected by the lesion. Following lesions in the ventral striatum fiber degeneration could always be observed in the ventral peduncle of the lateral forebrain bundle.

Corresponding terminal degeneration was found in the anterior and posterior entopeduncular nuclei, the tegmentum mesencephali, the substantia nigra, the prerubral area, the mesencephalic central grey and the lateral cerebellar nucleus. When the large celled part of the ventral striatum was involved in the lesion additional degeneration could be traced to the nucleus rotundus via the dorsal peduncle of the lateral forebrain bundle.
The functional morphology and possible taxonomic significance of the parapodia of the maldanid polychaetes Clymenella torquata and Euclymene oerstedi
Authors: Pilgrim Muriel
Published: February 2005

The morphology of the chaetae of the maldanid polychaetes Clymenella torquata (Leidy) and Euclymene oerstedi (Claparède) (= Caesicirrus neglectus Arwidsson, '11) are described and related to movements observed in the laboratory. Graphs are constructed of the number and length of the neuropodial chaetae of each chaetiger throughout the body of Clymenella and of species of the genera Euclymene, Macroclymene and Axiothella, and show a characteristic and relatively constant pattern for each species. This work suggests that in making taxonomic decisions, more attention should be paid to the overall pattern of the neuropodial chaetae and less to the confusing distinction between aciculae and rostral uncini.
The actions of three hamstring muscles of the cat: A mechanical analysis
Authors: Peters Susan E. , Rick Christine
Published: February 2005

An analysis of mechanical and architectural aspects of three hamstring muscles in the cat, semitendinosus (ST), semimembranosus anterior (SMa), and semimembranosus posterior (SMp), is presented based on whole muscle tetanic tension profiles. Length‐active tension curves for each muscle were obtained by electrical stimulation of the whole muscle with a train of stimuli at 100 pulses per second (pps) for 600 milliseconds.

Information from motion picture analysis (Goslow et al., '73) and electromyographic (EMG) activity (Engberg and Lundberg, '69) as seen during the step cycle is combined with analysis of joint torques to present a picture of the differential functions of the three muscles. The length‐active tension characteristics of ST and SMa are such that they develop high amounts of tension throughout their physiological excursions. Maximal tension is produced over a much more limited range by SMp. A division of labor for the three muscles is proposed: the one‐joint SMa is shown to be a primary hip extensor whose action facilitates smooth oscillation of the leg. Torque and electrical activity during the step cycle indicate the two‐joint ST is a primary knee flexor. The more limited range of maximum torque and variable EMG pattern of the other two‐joint muscle, SMp, relate to the fact that it has primary activity during high speed gaits when it may act to initiate spine flexion and assist in hip extension.

Excursion and activity data have led to the conclusion that biarticular muscles (ST and SMp) may benefit from the combined action of two joints to maintain near maximal tension and torque during active phases of the step cycle. Thus, biarticular muscles may have evolved as much for the mechanical and physiological benefits they derive as for two‐joint action itself.
Ankle flexor muscles in the cat: Length‐active tension and muscle unit properties as related to locomotion
Authors: Goslow G. E. , Cameron W. E. , Stuart D. G.
Published: February 2005

The mechanical properties of the whole muscle and fast‐twitch muscle units of the cat hindlimb pretibial flexors have been explored and related to normal locomotion. Tibialis anterior (TA) is parallel‐fibered and functionally crosses a single joint, the ankle, whereas extensor digitorum longus (EDL) is pinnate and spans the ankle, knee, metatarsophalangeal and interphalangeal joints. The active tetanic tension of TA remains near its peak value over a range of muscle lengths associated with normal ankle movement. In contrast, the length‐tension curve of EDL is sharply peaked. However, normal corollary action of the knee, ankle and metatarsophalangeal joints during stepping minimizes EDL's excursion and maintains it at or near a length optimal for peak tension development. EDL is capable of producing synchronous but sterotyped digit and ankle movements while TA provides for independent ankle flexion at all relevant joint angles.

The mechanical properties of 84 TA and 98 EDL fast‐twitch muscle units were studied by measuring twitch contraction time (≤45 msec), peak tetanic tension, response to repetitive stimulation, and contractile fatigue resistance during electrical stimulation of single alpha axons, functionally isolated from ventral root filaments. These mechanical properties were essentially similar for both muscles with the exception of mean peak tetanic tension which was 30% lower for TA units (14 gm‐wt) than for EDL units (20 gm‐wt). A high proportion of units in both muscles demonstrated fatigue resistance which is reflective of the repetitive, phasic demand upon these muscles during locomotion.
Tongue evolution in the lungless salamanders, family plethodontidae. II. Function and evolutionary diversity
Authors: Eric Lombard R. , Wake David B.
Published: February 2005

A recently presented model of tongue projection dynamics is used to generate a series of predictions concerning morphologies to be expected under selection for increased distance of projection, increased speed of projection, and increased directional versatility. A general understanding of biomechanical events and the model are used as points of departure for making specific predictions concerning details of structure in skeletal, muscular and connective tissue components of the tongue and associated structures. Comparative methods are used to examine these predictions in the genera of plethodontid salamanders. These salamanders are known to project their tongues to different degrees, and this knowledge is used to test the hypotheses concerning morphological specialization. Three distinct groups of plethodontid salamanders have evolved specializations for long distance projection, and these genera differ from one another in important ways in respect to specific character complexes. For example, the tropical genera and Hydromantes use CBII as the major force transmission element in the skeleton, while Eurycea and its allies use CBI in this role. Hydromantes differs from both in having a uniquely proportioned and structured hyobranchial skeleton and associated musculature. Less extreme specializations for tongue projection are found in different combinations in three other groups. Finally, two distinct groups of generalized species having only limited tongue projection capabilities are recognized, each having a unique complex of inter‐related features. Each of these eight groups is recognized and characterized as a functional mode, and hypotheses concerning the biomechanical meaning of the character complexes of each are formulated.
The craniocaudal extent of the glycogen body in the domestic chicken
Authors: Sansone Frances M.
Published: February 2005

All birds have a glial enclosed, glycogen‐containing structure in the lumbosacral region of their spinal cords. Recently, a dorsal, central, glycogen‐rich area surrounding the central canal in the brachial spinal cord was described in domestic chickens. In order to topographically delineate and histochemically describe this structure, fresh, frozen serial sections of chicken brains and spinal cords were processed for glycogen content, phosphorylase, succinic dehydrogenase and cholinesterase activities. The glycogen‐rich area surrounding the central canal in the lumbosacral region is found at all levels of the spinal cord and lower medulla. In the upper medulla, it is located in the midline floor immediately ventral to the ependyma. It persists in this position until the level of the oculomotor complex where it ends. Phosphorylase positive regions closely parallel the glycogen distribution. No succinic dehydrogenase or cholinesterase activities are found in these areas.
The structure of the salivary glands of the human soft palate
Authors: Black Jerry B.
Published: February 2005

The glandular layer constitutes the greatest bulk of the human soft palate and is composed of individual compound tubulo‐acinar salivary glands. Connective tissue partitions of the submucosa divide the glandular layer into lobules of irregular shapes and sizes. The glands are interwoven and bound firmly together by a connective tissue stroma rich in elastic fibers. The secretory units consist of elongated, branched, and sometimes convoluted tubules lined by a single layer of pyramidal mucous cells.

Mucous secretion by acini is supplemented to some degree by mucous acinar cells, which were found as epithelial components of all ducts except the main excretory ducts, suggesting a diffuse distribution of progenitor cells. Some mucous acini communicate with highly convoluted intercalated ducts which occupy partially isolated positions within inter‐ and intralobular connective tissue septa. These ducts follow the connective tissue septa and eventually join the main duct system. The significance of this system of intercalated ducts is not known. A supplemental functional role is hypothesized.
On the neurosecretory system of Dendrobaena atheca Cernosvitov
Authors: Baid I. C. , Gorgees Najem S.
Published: February 2005

Four kinds of neurosecretory cells A, B, U and C are distinguished in the central nervous system of Dendrobaena atheca Cernosvitov. A cells, which show different morphological characteristics under different physiological states and during their cyclic changes, are the most active neurosecretory cells. They form the outer layer of the cortical cell zone in the cerebral ganglion. B cells are large and medium sized and are distributed in all parts of the central nervous system. U cells are found only in the sub‐pharyngeal ganglion while C cells are distributed in the sub‐pharyngeal as well as in the ventral nerve cord ganglion. The number and secretory activity of C cells decrease in caudal direction. Further, Gomori‐positive cells are also observed in the ganglia of the vegetative nervous system.

A rudimentary neurohaemal organ, the storage zone, has been observed in the cerebral ganglion and there appears to be another neurohaemal area in the ventral nerve cord ganglion. The storage zone is formed by the terminal ends of the axons of A cells. The chrome alum haematoxylin phloxin (CHP) and aldehyde fuchsin (AF) positive substances in the form of granules are found in this area. The cerebral ganglion is richly supplied by blood capillaries. The distal end of the axons of B cells are swollen like a bulb while in some cases the axons are united to form an axonal tract. Extra‐cellular material is abundant in different parts of the nervous system. In all cell types, the perinuclear zone is the first to show activity in the secretory cycle. It appears that the nucleus may be involved in the elaboration of the neurosecretory material in the cells.
Fine structure of the tracheoles of the lantern of a photurid firefly
Authors: Ghiradella H.
Published: February 2005

The lantern tracheoles of the firefly, Photuris, are unusual in that their walls are reinforced by cuticular bars. The tracheoles are stiff and resist collapse under conditions which flatten more typical tracheoles. This reinforcement and the structural resemblance of the tracheal end cell to cells considered to be active in moving ions and fluid is taken as evidence suggesting that the flash may be turned on and off by control of the oxygen supply and that said control may involve some sort of osmotic mechanism.
Observations on the morphology of the developing primate cornea: Epithelium, its innervation and anterior stroma
Authors: Ozanics V. , Rayborn M. , Sagun D.
Published: February 2005

A survey is made of some ultrastructural features of the developing cornea of Macaca mulatta. The observations are confined to the anterior central area, starting with the lens vesicle stage and progressing through midgestation, when the morphologic characteristics of the cornea are fully established. Subepithelial filaments and some partially aggregated collagen fibrils are present in the earliest embryo and are of a size and appearance similar to those in the future vitreous cavity. Epithelial secretory activity points to, but does not prove direct contribution to the deposition of the acellular matrix components beneath it. No trace of a structured, orthogonal collagenous stroma can be visualized. The primitive endothelium forms prior to the fibroblast invasion of the distended filamentous matrix. Bowman's layer has undoubted epithelial contributions. Its aggregated collagen fibrils have approximately the same diameter as those of the anterior stroma. Intraepithelial appearance of single nerve fibers and fascicles takes place during the first trimester of gestation, as soon as the two continuous epithelial layers are formed. Terminal areas approach closely to the basal cell's nucleus, without touching it. The plasmalemma of the invaginating nerve fiber is surrounded by that of the epithelial cell in a mesaxon‐like manner, with occasional gap junctions uniting adjoining neural and epithelial cell membranes. The fetal neurites contain microtubules, some clear vesicles and dense vacuoles resembling those of mature monamine and non‐monamine neurons. Mitochondria are small and compact, their presence indicating a high rate of metabolic activity in the immature terminal area.
A histochemical study of the muscles of Drosophila melanogaster
Authors: Deak I. I.
Published: February 2005

The thoracic muscles of Drosophila melanogaster can be classified into two classes, the fibrillar and the tubular muscles, on morphological grounds. Histochemical techniques were used to characterize these two classes of muscle according to their content of various enzymes (α‐glycerophosphate, NAD‐dependent isocitrate, malate and succinate dehydrogenases, fumarase, acid phosphatase, adenosine triphosphatase and acetylcholinesterase) and of glycogen. These investigations showed that the two muscles types are histochemically very different and, further, that the morphologically similar tubular muscles are heterogeneous with respect to their enzyme content. In particular, the tergal depressor of the trochanter of the second leg, the largest of the tubular muscles, has considerably less of all the enzymes studied, with the exception of acetylcholinesterase, than all the other tubular muscles examined. The histochemical techniques were also used to follow the changes in enzyme levels that occur during development of the indirect flight muscle fibres. All the enzymes that are present in adult flight muscles showed an increase in staining intensity throughout muscle development. Some minor differences were observed in the time of appearance and rate of increase of intensity of the different enzymes.
Anatomical observations on the ending of the human thoracic duct
Authors: Zorzetto Neivo Luiz , Ripari Wagner , De Freitas Valdemar , Seullner Geraldo
Published: February 2005

Fifty‐one cadavers of human adults of both sexes were examined for the raminfications and site of opening of the cervical segment of the thoracic duct. It was found that the duct opened into veins of the neck through either one (84.31%) or two branches (15.69%). The most frequent site of opening was in the junction of the left internal jugular vein with the subclavian vein (18 individuals), but another frequent site (15 individuals) was in the internal jugular vein. The duct opened at the angle formed by the internal jugular vein and the internal posterior jugular vein in five individuals, and at a variety of the other locations in the remaining cadavers. These results are compared with the findings of previous investigators.
Microscopy of the junctional region between human coronal primary and secondary dentine
Authors: Scott John N. , Weber Dennis F.
Published: February 2005

The junction between human primary dentine and regular and irregular secondary dentine was examined with a number of different light and electron microscopic techniques. In decalcified material, a narrow band along the innermost surface of the primary dentine stained intensely. The walls of the tubules within the band stained intensely, whereas the tubular walls within the bulk of the primary dentine were not stained. Generally, the walls of the tubules in both types of secondary dentine were also preferentially stained. Although not readily apparent in ground sections, observations of thin sections revealed a dramatic reduction in the number of tubules in regular secondary dentine. Generally, the radiodensity of the intertubular matrix was the same in primary and secondary dentine and the intensely stained band was not seen radiographically. The pulpal ends of the tubules in primary dentine were often occluded with a material having the same radiodensity as peritubular matrix. Both patent and occluded tubules were seen in irregular secondary dentine. Scanning electron microscopy of acid‐etched specimens of secondary dentine revealed that some tubules had irregular walls of highly mineralized matrix which was less acid‐soluble than the peritubular matrix of primary dentine.
External morphology of Xyleborus ferrugineus (Fabr.) (Coleoptera: Scolytidae). I. Head and prothorax of adult males and females
Authors: Kingsolver Joel G. , Norris Dale M.
Published: February 2005

The overall body dimensions and external morphology of the head, head appendages, prothorax, and prothoracic legs of the adult haploid male and diploid female Xyleborus ferrugineus (Fabricius) were examined by scanning electron microscopy and light microscopy, and analyzed for variation. The female is significantly larger (1.26 X) than the male. The length/width ratio of both the pronotum and elytron, and the pronotum‐length/elytron‐length ratio are significantly different in the male and female. These findings indicate a distinct sexual dimorphism in general body form. There is significantly greater variability in pronotal length and width in the male than the female. There are sexual differences in setal patterns and setal size variabilities on the dorsal pronotum and the terminus of the antennae.
Development of dorsoventral polarity and mesentoblast determination in Patella vulgata
Authors: van den Biggelaar J. A. M.
Published: February 2005

In Patella vulgata the 32‐cell stage represents a pause in the mitotic activity prior to the differentiation of the mesentoblast mother cell 3D. At the onset of this stage, the embryo is radially symmetrical. Nevertheless, the plane of bilateral symmetry is indicated as it passes through the macromeres forming the vegetal cross‐furrow. From the early beginning of the 32‐cell stage, all four macromeres intrude far into the interior and touch the centrally radiating cells of the first quartet of micromeres. The two cross‐furrow forming macromeres (3B and 3D) intrude the farthest and come into contact with the greatest number of micromeres. Finally, the contacts are extended significantly and maintained with only one of these macromeres. From that moment, this cell can be called the macromere 3D and the dorsoventral axis is determined. The evolution of the internal cell contacts between the micromeres of the first quartet and the macromeres indicates an essential role of the former in the determination of one of the latter as the mesentoblast mother cell, and thus in the determination of dorsoventral polarity.
Ultrastructure of the acinar cells in the submandibular gland of the nine‐banded armadillo
Authors: Ruby John R. , Canning Harold B.
Published: February 2005

There are two discrete lobes comprising the armadillo subman‐dibular gland. These two lobes can be defined grossly, histochemically and morphologically with the light and electron microscope. The minor lobe stains more intensely with PAS and AB. When viewed in the electron microscope, the secretory granules of the acinar cells within this lobe appear mucous‐like. The granules of the demilune cells are slightly different in appearance. The secretory granules of the acinar cells in the major lobe contain many dense foci embedded in a fibrillar matrix, a substructure not described previously. The demilune cells of this lobe contain secretory granules with a mucous‐like structure which is consistent throughout the entire lobe. As in the minor lobe, these demilune cells stain very intensely with PAS and AB.
The preglossale of Passer (Aves: Passeriformes) ‐ a skeletal neomorph
Authors: Bock Walter J. , Morony John
Published: February 2005

A skeletal neomorph – the preglossale – is described from the tip of the tongue in Passer. This medial unpaired skeletal element is a dorsally open trough articulating with the anterior tips of the paraglossalia and supporting the heavy epidermal pad of the seed‐cup. The large paired Mm. hypoglossus anterior originate from the posterior half of the preglossale and insert onto the anterior bodies of the paired paraglossalia; they serve to depress the anterior portion of the preglossale. A regular pattern of dermal papillae is present in the seed‐cup; these are arranged in about 20 rows of six to 8 papillae per row. Each papilla contains a series of Merkel cells and associated nerve endings (touch receptors). The seed‐cup serves to orient and hold the seed in place while it is being husked; the battery of tactile receptors provides information on the position of the seed on the tongue. The preglossale serves to support the seed‐cup and to change its shape – the curvature of the dorsal surface – as it is depressed relative to the paraglossalia. The paraglossale and associated features of the seed‐cup in Passer would provide a valuable preparation to study a diversity of problems such as developmental interactions between endomesodermal and ecto‐mesenchymal skeletal features, the ontogenetical development of Merkel cells, and the sensory physiology of Merkel cells and their associated nerve endings as tactile corpuscles.
Insertions and functions of certain flexor muscles in the hind leg of rodents
Authors: Hildebrand Milton
Published: February 2005

This survey includes 58 genera of rodents from 26 families. The medial tarsal bone is probably unique to the order. Its presence, nature, and constant relationship with M. tibialis posterior are discussed. This muscle inverts and supinates the pes at the astragulo‐navicular joint and moves the ankle.

The M. flexor tibialis inserts on the medial sesamoid, on this sesamoid and the integument, on the sesamoid and the tendon of M. flexor fibularis, on the latter tendon only, or on the integument only. The occurrence, nature, and cam‐like action of the sesamoid are described. A distal segment of the tendon of M. flexor tibialis usually extends from the sesamoid to either the first phalanx of the first digit or to fascia of an adjacent muscle.

Functions of the medial sesamoid include (1) stabilization of the tendon of M. flexor tibialis, (2) deflection of this tendon to benefit flexion of the first phalanx, (3) winching of the medial tarsal ligament to flex the first metatarsal, (4) control of the angle of insertion of the tendon to provide flexion or abduction of the first digit as appropriate during swimming, (5) mechanical multiplication of the tension in the tendon between the segments proximal and distal to the sesamoid, and (6) longitudinal folding of the sole of the pes to grip the substrate, as in climbing.
Cell renewal in the epithelium of the alimentary tract of the larval lamprey, Petromyzon marinus L.
Authors: Hansen Susan J. , Youson John H.
Published: February 2005

Light microscopic autoradiography with 3H‐thymidine demonstrates that the three regions of the alimentary tract in the larval (ammocoete) lamprey, Petromyzon marinus L., possess different patterns for renewing their epithelium. In the oesophagus, columnar and mucous cells originate from stem cells located at the bases of folds and migrate to the tops of the folds where they are apparently extruded. Ciliated cells, located only at the tops of the folds, seem to differentiate from migrating columnar cells. In the anterior intestine, stem cells are present throughout the epithelium so that there is limited migration of cells and their extrusion occurs randomly. In the posterior intestine, the stem cells located at the bases of the typhlosole provide a continuous population that differentiates and migrates to the top of the typhlosole and to the opposite epithelial wall where they are presumably extruded. The rates of cell renewal in all three epithelial regions of the alimentary tract are slower in animals maintained at 10 ± 1°C compared with those kept at 21 ± 1°C. Comparatively, ammocoetes have the least specialized system for cell renewal known in the alimentary tract of a vertebrate.
The cat step cycle: Electromyographic patterns for hindlimb muscles during posture and unrestrained locomotion
Authors: Rasmussen S. , Chan A. K. , Goslow G. E.
Published: February 2005

The telemetered electromyographic activity (EMG) of select hindlimb muscles of unrestrained cats during standing, walking, trotting, and galloping have been recorded. Simultaneous cinematographic records permitted close correlation of muscle activity and locomotor behavior. In general, the pattern of extensor activity of the ankle, knee, and hip during locomotion is fairly consistent, while that of the flexors is more variable.

Changes in basic EMG patterns from walk, to trot, to gallop are most evident in the two‐jointed muscles associated with the knee and hip. Progressively greater variation of activity onset and cessation can be seen among extensor muscle groups from the walk, to trot, to gallop. Co‐activation of the joint extensors and flexors, especially of the hip, at the end of the stance phase (E3) is slight in the walk, moderate in the trot, and considerable in the gallop. These EMG changes are necessary to meet the demands imposed upon the musculature at the faster gaits, particularly galloping, which include limb rigidity as related to loading, momentum as related to the limb's directional change from the stance phase to the swing phase, and lower spinal movements.

The peroneal muscles of the ankle and the gluteal muscles of the hip show extensor activity and act as joint stabilizers during locomotion. Both biceps femoris anterior muscle and biceps femoris posterior muscle show consistent hip extensor patterns at all gaits. During quiet standing, extensor activity about the knee, ankle, and metatarsophalangeal joints is evident; but the hip extensor and flexor musculature is remarkably silent.

EMG data for unrestrained cats are compared to those of dogs on a treadmill (Tokuriki, '73a,b, '74; Wentink, '76) and those recorded from decerebrate cats (mesencephalic preparation) during controlled locomotion (Gambaryan et al., '71). The EMG patterns from decerebrate cats are more consistent at the walk and gallop within functional groups of muscles at the ankle, knee, and hip than the EMG patterns observed in unrestrained cats or animals moving on a treadmill.
Studies on the renal sac of the ascidian Molgula manhattensis. I. Development of the renal sac
Authors: Saffo Mary Beth
Published: February 2005

The renal sac of the ascidian family Molgulidae (Tunicata, phylum Chordata) has been thought to function as a kidney, yet its structure, contents and activities seem incompatible with current generalizations regarding excretory processes in marine animals. The development of the renal sac is described here as part of a general effort to reexamine the organ's role in Molgula manhattensis. Light microscopy of living animals and fixed material has shown the following: (1) The renal sac begins to sequester concretions before the heart starts beating and before feeding begins. Therefore, blood circulation by heartbeat is not necessary for production or transport of the initial concretions, whatever its effects may be on the renal sac in older individuals. Ingested food cannot provide the initial concretion material. (2) In laboratory‐raised animals, concretions appear in the renal sac before “renal sac organisms” (fungus‐like organisms seen in the renal sac of all field‐collected adults) can be detected. Thus, at least some portion of the concretions can be produced by Molgula in the absence of renal sac organisms. (3) No openings have been detected in the renal sac at any stage of its development, nor is there any evidence that concretions are dissolved or transported out of the renal sac. (4) The development and morphology of the renal sac are consistent with the hypothesis that the organ is an epicardial derivative, except that the renal sac arises from post‐pharyngeal (presumptive gut) endoderm, rather than pharyngeal endoderm.
The ultrastructure of the metathoracic femoral extensors of the cockroach, Periplaneta americana
Authors: Fourtner Charles R.
Published: February 2005

The ultrastructure of the femoral extensors of the metathoracic leg of the cockroach, Periplaneta americana was studied to determine morphological correlations with the known patterns of innervation, physiological properties and biochemical properties. Three different types of muscle fibers were described. Type 1 consisted of short sarcomeres (mean 3.7 μm), few mitochondria and sparse glycogen‐like material; Type 2, short sarcomeres (4.2 μm), numerous mitochondria, large amounts of glycogen; Type 3, long sarcomeres (7.5 μm), numerous mitochondria and large amounts of glycogen. A qualitative examination of the sarcoplasmic reticulum (SR) and transverse tubular system (TTS) revealed the density of SR and TTS to be greatest in Type 1 and least in Type 3. There were obvious correlations between the morphological features and the other known characteristics of these muscle fibers. The role of these different muscle fiber types in different locomotory behaviors was discussed. In summary, the three types of muscle fibers are used in three different behaviors: Type 1, rapid walking; Type 2, slow walking; Type 3, postural control.
Functional analysis of the shoulder girdle of cats during locomotion
Authors: English Arthur William
Published: February 2005

The movements of the shoulder girdle of eight adult cats during overground stepping were studied, using standard slow motion cinematographic techniques. The patterns of activity of shoulder muscles were examined, using simultaneous intramuscular electromyography. Walking, trotting and galloping steps were analyzed from digitized single motion picture frame images. Angular movements of the shoulder girdle consist of biphasic flexion and extension of the shoulder joint and a monophasic flexion‐extension alternation of the scapula on the thorax during each step cycle. In addition, the center of the scapula moves craniad during the swing phase and caudad during the stance phase with respect to a fixed reference point on the animal. Similar vertical movements of the center of the scapula also occur in each step cycle. Results of EMG studies of the 17 muscles capable of acting on the shoulder girdle indicate that three overall patterns of activity are found: (1) a pattern typical of extensor muscles, active during all the extension epochs; (2) a pattern typical of flexor muscles, active during the flexion epoch; and (3) a biphasic pattern of activity, active twice in each step. These data are used, along with a re‐examination of previous models of the mechanics of the shoulder girdle of carnivores to examine the function and mechanics of shoulder motion. It is concluded that the rotary and translatory movements of the shoulder girdle during stepping combine to enhance step length.
Ultrastructural studies on the formation of yolk granules in the statoblast of a fresh‐water bryozoan, Pectinatella gelatinosa
Authors: Terakado Kiyoshi , Mukai Hideo
Published: February 2005

The formation of protein‐carbohydrate yolk in the statoblast of a fresh‐water bryozoan, Pectinatella gelatinosa, was studied by electron microscopy. Two types (I and II) of yolk cells were distinguished. The type I yolk cells are mononucleate and comprise a large majority of the yolk cells. The type II yolk cells are small in number; they become multinucleate by fusion of cells at an early stage of vitellogenesis. In both types of yolk cells, electron‐dense granules (dense bodies) are formed in Golgi or condensing vacuoles, which are then called yolk granules. For the formation of yolk granules, the following processes are considered: 1. Yolk protein is synthesized in the rough‐surfaced endoplasmic reticulum (RER) of the yolk cells. 2. The synthesized protein condenses in the cisternal space of the RER and is packaged into small oval swellings, which are then released from the RER as small vesicles (Golgi vesicles, 300‐600 A in diameter). 3. The small vesicles fuse with one another to form condensing vacuoles, or with pre‐existing growing yolk granules. 4. In the matrix of the condensing vacuoles or growing yolk granules, electron‐dense fibers are fabricated and then arranged in a paracrystalline pattern to form the dense body. 5. After the dense body reaches its full size, excess membrane is removed and eventually the yolk granules come to mature. Toward the end of vitellogenesis of the yolk cells, the cytoplasmic organelles are ingested by autophagosomes derived from multivesicular bodies and disappear.