bluuebunny/crossref_metadata_2025 huggingface dataset:
Model of jaw depression during feeding in Astatotilapia elegans (Teleostei: Cichlidae): Mechanisms for energy storage and triggering
Authors: Aerts Peter , Osse J. W. M. , Verraes W.
Published: February 2005

Suction feeding in Astatotilapia elegans occurs by a series of rapid, coupled movements of various head parts. The lower jaw rotates with respect to the neurocranium through an angle of 62° in less than 15 ms. The power requirements for jaw depression are calculated from a mathematical model and may reach a peak of ±4 watt in a 12‐cm‐long specimen. Data from the literature on mechanical output of fish muscle suggest that a muscular volume equal to 44% of the volume of the fish (= 45 cm3) should be required, if it is premised that movement and muscle shortening are directly coupled. Therefore, we assumed that storage and release of strain energy must be considered. The work demands for depression equal 0.014 J. The amount of energy storable in only three pairs of head ligaments can be estimated between 0.008 J and 0.05 J. The use of strain energy implies initial blocking and subsequent triggering of the movement. The position of the hyalomandibular connection, dorsal to the mandibular‐suspensorial articulation, appears to be of crucial importance in balancing the forces of sternohyoideus and the body muscles. Triggering at the onset of jaw depression occurs by the contraction of the levator operculi. The line of action of the hyalomandibular connection is lowered beneath the jaw suspension, which raises the equilibrium of forces. Elastic recoil can occur thereafter.
Location of the rostral end of the longitudinal brain axis: Review of an old topic in the light of marking experiments on the closing rostral neuropore
Authors: Puelles L. , Domenech‐Ratio G. , Martinez‐De‐La‐Torre M.
Published: February 2005

The rostral end of the forebrain was classically defined on the basis of descriptive data. Different assumptions on the mode of closure of the rostral neuropore caused three different theories of the rostral end of the forebrain to be formulated (His 1893a; von Kupffer, '06; Johnston, '09). Some recent descriptive and experimental data have put these theories into question.

A piece of black nylon thread was inserted through the rostral neuropore of chick embryos and was fixed to its ventral lip. These operations were done at all intermediate stages during the process of closure of the rostral neuropore. The embryos were sacrificed at a later stage, by which time the neuropore had disappeared.

In the cleared specimens the threads always lay at the same site, namely the upper border of lamina terminalis, irrespective of the stage at which the marker was inserted. These results stand against His's conception ((1893a, b) of a sutura terminalis and support the single mechanism of sutura dorsalis during closure of the rostral neuropore. The marking data therefore imply that the topologic rostral end of the forebrain lies at the upper limit of lamina terminalis, as proposed by von Kupffer, '06).
Skull development during anuran metamorphosis: I. Early development of the first three bones to form—the exoccipital, the parasphenoid, and the frontoparietal
Authors: Hanken James , Hall Brian K.
Published: February 2005

In anuran amphibians, cranial bones typically first form at metamorphosis when they rapidly invest or replace the cartilaginous larval skull. We describe early development of the first three bones to form in the Oriental fire‐bellied toad, Bombina orientalis—the parasphenoid, the frontoparietal, and the exoccipital—based on examination of serial sections. Each of these bones is fully differentiated by Gosner stage 31 (hindlimb in paddle stage) during premetamorphosis. This is at least six Gosner developmental stages before they are first visible in whole‐mount preparations at the beginning of prometamorphosis. Thus, developmental events that precede and mediate the initial differentiation of these cranial osteogenic sites occur very early in metamorphosis—a period generally considered to lack significant morphological change. Subsequent development of these centers at later stages primarily reflects cell proliferation and calcified matrix deposition, possibly in response to increased circulating levels of thyroid hormone which are characteristic of later metamorphic stages. Interspecific differences in the timing of cranial ossification may reflect one or both of these phases of bone development. These results may qualify the use of whole‐mount preparations for inferring the sequence and absolute timing of cranial ossification in amphibians.
Metamorphosis of the marine bryozoan Membranipora membranacea: An ultrastructural study of rapid morphogenetic movements
Authors: Stricker Stephen A.
Published: February 2005

The colonial marine bryozoan Membranipora membranacea produces a planktotrophic cyphonautes larva that is encased by a triangular bivalved shell. Following a relatively long free‐swimming phase, the cyphonautes larva settles and undergoes a dramatic metamorphosis to become the sessile progenitor of the colony, referred to as the ancestrula. This paper examines the initial morphogenetic movements of metamorphosis that transform the cyphonautes larva into an incipient ancestrula. At the onset of metamorphosis, contractions of the striated median muscles situated along the anterior and posterior margins of the larva cause a retraction of the larval apical organ and a centripetal movement of the anterior and posterior ends of the larva. Concurrently, the ciliated corona at the base of the larva is pulled within the shell by contractions of the striated lateral muscles. As the larva assumes a more spherical shape, the posterior margins of the shell are spread apart, and the internal sac is everted. Eversion of the sac is apparently achieved by contractions of the lateral muscles that cause a buckling of the shell in the apical‐basal direction. The neck region of the everted sac secretes adhesive granules that attach the larva to the substratum. Subsequently, contractions of the nonstriated sac muscles fold the valves of the shell over each other and draw the larva toward the substratum. The initial events of metamorphosis that culminate in the attachment and flattening of the larva are completed in 10–15 seconds. In the subsequent few minutes, the lateral edges of the everted sac fuse with the neighboring margins of the aboral epithelium underlying the shell and thus form the fully sealed body wall of the incipient ancestrula.
Morphology of the exocrine pancreas of the Southern Hemisphere lamprey, Geotria australis, and changes during metamorphosis
Authors: Hilliard R. W. , Potter I. C.
Published: February 2005

The distribution and histology of zymogen cells and the activity of digestive enzymes have been examined in the alimentary canal of larval, metamorphosing (stages 1–7), and adult Geotria australis (Geotriidae). Comparisons of the arrangement of the larval and adult zymogen cells are made with those observed in Mordacia mordax, a representative of the other Southern Hemisphere lamprey family (Mordaciidae), and with those reported elsewhere for holarctic lampreys (Petromyzontidae). In larval G. australis, epithelial zymogen cells are mainly restricted to the prominent pair of tubular diverticula which project forward from the oesophageal/intestinal junction. By contrast, zymogen cells of adults are present in the epithelium of both the anterior intestine and the intestinal caecum, a structure located at the new and more anterior oesophageal/intestinal junction which forms during metamorphosis. Amylolytic activity was greater in the larval divrticula than in the adult caecum, whereas the reverse was true for tryptic activity. This feature presumably reflects the high dietary contribution made by detritus and algae during the filter‐feeding larval phase and by host muscle tissue during the predatory adult phase. The high tryptic activity in the caecum must promote the early breakdown of host tissue and thereby facilitate the digestion of lipids in the anterior intestine where lipolytic activity is high. At the commencement of metamorphosis, digestive activity and the number of zymogen cells declines markedly. By stage 4 the intestine has rotated anticlockwise almost 360°; the two larval diverticula have disappeared; and the new exocrine caecum of the adult has started to develop from a forward proliferation of intestinal mucosal cells. While the exocrine pancreatic tissue of larval M. mordax is unique amongst lampreys in its location within a single, large diverticulum containing an extensive network of mucosal folds, that of the adult is found in the same position as in G. australis and holarctic lampreys.
The morphogenesis of molluscan shells: A mathematical account using biological parameters
Authors: Løvtrup Søren , Løvtrup Michael
Published: February 2005

In attempts to account mathematically for the morphogenesis of biological structures it is important that the parameters chosen for the purpose should be “biological,” that is, they should refer directly to the growth processes through which the structure is formed.

Molluscan shells are formed by accretional growth at the mantle edge, and the parameters used for the mathematical description of their formation should therefore refer to events taking place there.

In the best of previous attempts to solve this problem, two out of three form parameters have met with this demand, but it was not possible to eliminate β, half the apical angle of the cone on which lie the centers of successive whorls.

It is shown here that β may be eliminated for many forms of molluscan shells, and when this is not the case β may indeed be referred to processes taking place at the mantle edge.
Reproduction in the mexican leaf frog, Pachymedusa dacnicolor. IV. Spermatogenesis: A light and ultrasonic study
Authors: Rastogi Rakesh K. , Bagnara Joseph T. , Iela Luisa , Krasovich Margaret A.
Published: February 2005

Primary spermatogonia have highly lobate nuclei and can be distinguished as pale and dark types on the basis of nuclear and cytoplasmic features. Nuclei of secondary spermatogonia are also lobate. Primary spermatocytes have spherical nuclei and display synaptinemal complexes in late zygotene‐pachytene. Spermatocytes are connected by intercellular bridges, which persist through spermiogenesis. During spermiogenesis no acrosomal granule is formed. The acrosomal vesicle is large and forms in the apical part of the cell. A helical system of perinuclear microtubules accompanies the phase of nuclear elongation. Microtubules disappear in late spermatids and there forms a compact bundle of filaments which extends into the subacrosomal area. These filaments probably derive from the breakdown of the microtubules. A mitochondrial sleeve is formed around the proximal portion of the tail and much of it is cast off in the mature spermatid. The tail is composed of a spirally coiled contractile element and a stiff fibrous axial rod connected together by an undulating membrane. The axial rod and the axoneme‐associated rodlet derive from a dense, juxtacentriolar fibrous mass. Sertoli cells surrounding the spermatogonial and spermatocyte cysts are slender and have oblong nuclei. In contrast, those associated with spermatids are columnar and have deeply indented nuclei. They possess many Golgi complexes, elongated mitochondria, cisternae of smooth endoplasmic reticulum, lysosome‐like bodies, masses of glycogen particles, few lipid droplets, and an array of microtubules running longitudinally around the elongating spermatid nuclei. Desmosomes are formed between adjacent Sertoli cells.
Bipolar cells in the chicken retina
Authors: Quesada A. , Prada F. A. , Genis‐Galvez J. M.
Published: February 2005

Using the Golgi staining method with the modification suggested by Colonnier (J. Anat. 98:327, 1964), we have carried out a morphological study of the bipolar cells of the chicken and classified them into various morphological types. In the classification given we have described the existence of seven main groups of bipolar cells that differ in shape and spread of their dendritic network. In addition, within each of these groups we have taken into account other morphological features, such as the presence and position of Landolt' s club, the size of the dendritic field, the presence of an accessory dendritic process, the position of the perikaryon in the INL. The stratification of the axonal ending is demonstrated but cannot be related to the classification based on dendritic morphology that we have chosen.
Ultrastructure of the Drosophila larval salivary gland cells during the early developmental stages. I. Morphological studies
Authors: Thomopoulos George N.
Published: February 2005

Larval salivary gland cells of seven Drosophila species from the melanogaster group were studied during the early third‐instar period. Similar cytoplasmic organization was seen in both the distal and proximal parts of the gland. The cytoplasm contained a large number of free ribosomes, but only a few rough endoplasmic reticulum profiles; the nucleolus was very large. Golgi complexes consisted mainly of vesiculated cisternae. Small secretory granules (diameter, 0.23–0.32 μm) are produced during this period and in some species contain both granular and filamentous material. These granules appeared to be secreted by a peculiar “apocrine‐type” secretion after enclosure of granules into microvillar “lacunae.” A digestive function is attributed to the secretory material. During the third instar, a close association between the salivary gland and the fat body also was observed. The physiological significance of this association seems to be related to the transfer of nutrients, enzymes, or membranous materials from fat body to salivary gland.
Organization of the vomeronasal organ in a plethodontid salamander
Authors: Dawley Ellen M. , Bass Andrew H.
Published: February 2005

Salamanders in the family Plethodontidae show a unique behavior (nose‐tapping) and have unique structures (nasolabial grooves) that may be used specifically to convey chemicals to the vomeronasal organ. The nasal structure of Plethodon cinereus was studied to determine if there is enhanced development of the vomeronasal organ compared with other salamander families that would correlate with use of these unique features. The vomeronasal organ in salamanders is found in a ventrolateral diverticulum of each main olfactory organ. P. cinereus has a more anteriorly placed vomeronasal organ within the diverticulum, and the posterior limit of each nasolabial groove is adjacent to the anterior limit of the vomeronasal organs. This suggests that the grooves deliver chemicals preferentially to the vomeronasal organs instead of to the main olfactory organs. In addition, the vomeronasal sensory epithelium is thickest anteriorly and is at its thinnest at about the level corresponding to the location of the vomeronasal organ in other salamander families. These adaptations suggest a specific mechanism of odorant delivery to the vomeronasal organ in plethodontid salamanders not found in other salamander families.
Arthropod immune system: I. Comparative light and electron microscopic accounts of immunocytes and other hemocytes of Blattella germanica (Dictyoptera: Blattellidae)
Authors: Chiang A. S. , Gupta A. P. , Han S. S.
Published: February 2005

Light microscopy (LM) and scanning (SEM) and transmission electron microscopy (TEM) disclose seven types of hemocytes in adults of the German cockroach, Blattella germanica (Dictyoptera: Blattellidae)—namely, prohemocytes (PR), granulocytes (GR), plasmatocytes (PL), spherulocytes (SP), adipohemocytes (AD), coagulocytes (CO), and oenocytoids (OE). Their shape, size, surface appearance, and internal ultrastructure are characterized here. The shapes and relative sizes of hemocytes noted in vitro have been compared with those flowing through the wing veins (in vivo). The GRs constitute more than 90% of the hemocyte population and have roles in the defense system such as encapsulation and phagocytosis. They are characterized by numerous cytoplasmic granules and marginal microtubular bundles, which are commonly noted in the blood cells of both vertebrates and invertebrates, but have been rarely reported in insect hemocytes. The PRs are characterized by being spherical and small, having a relatively large nucleus and a small area of cytoplasm. The polymorphic PLs have some micropapillae on the cell surface and fewer granules than the GRs. The SPs are characterized by an oblate shape, raspberrylike appearance in SEM, and many spherules in the cytoplasm. The ADs are spherical and have large, refringent fat droplets. The COs possess a distinctive cartwheellike appearance when observed by LM but resemble GRs in TEM preparations. The OEs are opaque and often have an eccentric nucleus. Of the seven types of hemocytes, all, except the COs, can be recognized both in vivo and in vitro by LM; the COs can be recognized only in vitro. SEM does not allow the COs to be distinguished from the GRs, except in samples in which coagulation has occurred. All hemocyte types can be recognized by TEM. Thus, all three types of microscopy allow the various types of hemocytes to be recognized; unequivocal discrimination among the cells is best achieved by combining all the three kinds of microscopy.
Cochlea in old world mice and rats (Muridae)
Authors: Burda Hynek , Ballast Lothar , Bruns Volkmar
Published: February 2005

Morphometric analysis of the cochlea was performed in wild and laboratory murids: Mus musculus, Apodemus sylvaticus, Rattus rattus, R. norvegicus, NMRI mouse, and Wistar rat. Results are based on light microscopic examination of surface specimens and serial sections and on three‐dimensional computer reconstruction. The cochleae have 1.75–2.2 coils. The length of the basilar membrane varies from 6.0 to 12.1 mm. Mean density of outer hair cells ranges between 363 and 411, inner hair cells 98 and 121, neurons 1,230 and 1,760 per 1 mm. Following parameters change from base to apex: basilar membrane width 66.0 (±8.2) to 175.0 (±24.7) μm, basilar membrane thickness 17.0 (±2.6) to (±0.1) μm, width of triad of outer hair cells 13.2 (±0.7) to 28.8 (±4.4) μm. The given numbers are mean “murid” values (with respective standard deviations). Maximum of dimensions of scalae is located at 10–15%, that of density of outer hair cells at 65%, density of inner hair cells at 2.8 mm, maximum of innervation density at 40–60% from the base. The following parameters are correlated with pinna size: length and maximum width of basilar membrane, dimensions of scalae, total number of receptors, and probably resolution capabilities. The following parameters are correlated with body size: maximum width of traid of outer hair cells, density and total number of neurons, ratio of neurons to receptors, apicobasal difference in basilar membrane stiffness and width of triad of triad of outer hair cells; inversely proportional is receptor density and ratio of outer to inner hair cells and probably low‐frequency cut‐off. Thickness, and minimum width of basilar membrane and triad of outer hair cells and probably high‐frequency cutoff are species‐specific and independent of pinna or body size. The parameters mentioned indicate that the examined murids are acoustically unspecialized mammals and their cochleae approximate the generalized plan for a mammalian cochlea. Differences between domesticated and wild murids are stated.
Molt staging in artemia adapted to drach's system
Authors: Criel Godelieve R. J. , Walgraeve Hilde R. M. A.
Published: February 2005

The molting cycle of Artemia is described and subdivided in stages A‐D3 according to the system of Drach. Determination of the stages is done in living animals by light microscopic observation of changes in the texture of the setal matrix of the exopodites. A parallel ultrastructural investigation of the integument was carried out to control the proposed staging scheme. The duration of each stage was calculated.
Extracellular matrix of sea urchin and other marine invertebrate embryos
Authors: Spiegel Evelyn , Howard Louisa , Spiegel Melvin
Published: February 2005

The extracellular matrix surrounding the sea urchin embryo (outer ECM) contains fibers and granules of various sizes which are organized in recognizable patterns as shown by ultrastructural studies, particularly stereoimaging techniques. The use of the ruthenium red method for retaining and staining the ECM, with modification of the Luft (Anatomical Record 171:347–368, 1971) method for invertebrate embryos, allows for the clarification of certain structures, particularly fiber compaction in the interzonal region, and microvillus‐associated bodies.

The inner ECM in the sea urchin embryo includes the basal lamina and blastocoel matrix. Stereoimages show that the fibers which are loosely distributed in the blastocoel matrix become compacted around the periphery of the blastocoel to form the basal lamina.

The ruthenium red method was also used on a number of marine invertebrate embryos and larvae, representing different phyla, to facilitate comparisons between their surface coats. The similarities observed in the specimens shown suggest that ECMs are widely found on marine invertebrate eggs, embryos, and larvae, and that they resemble vertebrate ECMs and may, therefore, have similar functions.
Skeletal muscle architecture of the rabbit hindlimb: Functional implications of muscle design
Authors: Lieber Richard L. , Blevins Field T.
Published: February 2005

The muscle‐fiber architecture of 29 muscles from six rabbits (Oryctolagus cuniculus) was measured in order to describe the muscular properties of this cursorial animal, which possesses several specific skeletal adaptations. Several muscles were placed into one of four functional groups: hamstrings, quadriceps, dorsiflexors, or plantarflexors, for statistical comparison of properties between groups. Antagonistic groups (i.e., hamstrings vs. quadriceps or dorsiflexors vs. plantarflexors) demonstrated significant differences in fiber length, fiber length/muscle length ratio, muscle mass, pinnation angle, and number of sarcomeres in series (P<.02). Discriminant analysis permitted characterization of the “typical” muscle belonging to one of the four groups. The quadriceps were characterized by their large pinnation angles and low fiber length mass ratios, suggesting a design for force production. Conversely, the hamstrings, with small pinnation angles, appeared to be designed to permit large excursions. Similar differences were observed between plantarflexors and dorsiflexors, which have architectural features that suit them for force production and excursion respectively. Although these differences were not absolute, they represented clear morphological distinctions that have functional consequences.
Larval morphology of the bryozoan Watersipora arcuata (Cheilostomata: Ascophora)
Authors: Zimmer Russel L. , Woollacott Robert M.
Published: February 2005

The larva of the ascophoran cheilstome Watersipora arcuata is described on the basis of serial 1‐μ sections, light microscopy of whole mounts, and scanning electron microscopy. Using lightly osmicated specimens, it was possible to map almost every cell on the larval surface. Limited observations on hatching and larval behavior are provided in conjunction with the anatomical description. Tissues of the larva are partitioned between those that function exclusively during the larval period and are degraded at metamorphosis as transitory tissues and those that will have postmetamorphic fates in formation of the ancestrula. Significantly, W. arcuata has two possible anlagen for the ancestrular polypide, the infracoronal cells in the oral hemisphere and the epidermal blastemal cells in the aboral hemisphere, rather than only one or the other of these as reported in other species. Also detailed are the supracoronal flange and groove, which are unique to this genus and are involved in the transmission of mycoplasma‐like organisms between successive generations of adults; two pairs of complex pigment cup ocelli; multiple intercoronal cells that are presumed to have varied sensory and mechanical functions; and the sensory, adhesive, and locomotory components of the pyriform organ. The larval anatomy of W. arcuata is compared with that of the larvae of the ctenostomes Alcyonidium gelatinosum (coronate), Bowerbankia imbricata (coronate), B. gracilis (coronate), and Flustrellidra hispida (shelled lecithotrophic) and of the cheilostomes Bugula neritina (coronate), Electra pilosa (cyphonautes), and Membranipora membranacea (cyphonautes). This study is the first detailed analysis of the larval structure of any ascophoran bryozoan and provides a necessary platform for subsequent analyses of embryology and metamorphosis.
Intercoronal cell complex of larvae of the bryozon Watersipora arcuata (cheilostomata: Ascophora)
Authors: Zimmer Russel L. , Woollacott Robert M.
Published: February 2005

The coronate larva of the ascophoran bryozoan Watersipora arcuata has a ring of 32 large, multiciliated coronal cells that are used for swimming. Fourteen pairs of small cells are intercalated between the lateral margins of adjacent coronal cells. These intercoronal cells are arranged in a precise pattern and are polymorphic: seven pairs have multiple cilia and seven pairs are mono‐ or oligociliated. Three pairs of multiciliated intercoronal cells have their cilia arranged as a whorl that is recessed in a pocket formed between the adjacent coronal cells, and they are thought to be photoreceptors that sense general light intensity. Two other pairs of multiciliated cells with cohesive tufts of cilia may be chemo‐ or mechanoreceptors. Roles of the other intercoronal cells in this species are not evident, but it is proposed that the majority, if not all, of them are sensory. The close proximity of all the intercoronal cells to the equatorial nerve ring is compatible with this interpretation. Analyses of the literature on cleavage patterns, pigment cup ocelli, and flagellar tufts that serve as balancers in coronate larvae lead us to propose that (1) an intercoronal cell is the sensory element of most, if not all, pigment cup ocelli of bryozoan larvae; and (2) intercoronal cells are not modified coronal cells but probably are specialized supra‐ and/or infracoronal ones that have migrated to an intercoronal position.
Embryonic development of the hemipteran insect Rhodnius prolixus
Authors: Kelly Gregory Mitchell , Huebner Erwin
Published: February 2005

The embryonic development of the hemipteran insect Rhodnius prolixus was studied by use of contemporary light and electron microscopy. Embryos were staged according to days postoviposition. Eggs laid on day one complete blastoderm formation and anatrepsis, the first phase of blastokinesis, by day 5. The embryo develops in a cephalocaudal orientation which is 180° to the anteroposterior axis of the egg. Subsequent development, prior to the second phase of blastokinesis (katatrepsis), leads to segmentation of the germ band, evagination of appendages, and histogenesis of germ layers. Concomitantly with these events, the amnion undergoes dramatic change. By day 7 the embryo begins a 180° revolution while migrating to the ventral surface of the yolk. This restores its polarity with respect to that of the egg and facilitates hatching. The serosa contracts, pulling the amnion and embryo anteriorly. Eventually the serosa is internalized at a point dorsal to the head and the lateral walls of the embryo grow up and surround the yolk. Development continues until day 15 when the embryo hatches as a first instar larva.
Scanning electron microscopy of epithelial surfaces of the sea anemone Acontiophorum niveum (Phylum Cnidaria): Class anthozoa
Authors: Eppard Robin A. , Highison Gregory J. , Mead Robert W.
Published: February 2005

Epithelium of the sea anemone Acontiophorum niveum is modified into four general arrangements of microappendages: (1) uniform microvilli covering pedal disc and column, (2) an interspersion of microvilli, ciliary cones, and kinocilia on tentacles, (3) flagella among an understory of microvilli from the oral disc, actinopharynx, filaments, and acontia, and (4) sparse flagella among irregular microvilli from endoderm. These arrangements are similar to those described previously in the epithelia of other anthozoans.
Structure of the stridulatory apparatus and analysis of the sound produced by Smicronyx fulvus and Smicronyx sordidus (coleoptera, curculionidae, erirrhininae, smicronychini)
Authors: Hyder Donald E. , Oseto Christian Y.
Published: February 2005

Wing folding spicules, elytral binding patches, and elytral locking devices of adult male and female seed weevils, Smicronyx fulvus LeConte and S. sordidus LeConte, involved in stridulation are described. Sound is produced by both sexes of the two species when the plectrum, paired conical teeth located along the anterior margin of the dorsally elevated seventh sternite, is struck against an elongate file, the pars stridens, on the under surface of the apical portion of each elytron. A second plectrum, on the sixth tergite, is well‐developed in males of both species and is used by males to produce sound before and during mating.

Sex‐specific and species‐specific differences in the sound produced is attributed to structural variation in the pars stridens and the elytra. The pars stridens determines frequencies, while the elytra may further modify the sound. The frequency range for male S. fulvus is 1,000 cycles per second (cps) through 13,000 cps and for male S. sordidus is 2,500 cps through 13,000 cps. The frequency range for female S. fulvus is 2,000 cps through 11,500 cps and for female S. sordidus is 900 cps through 11,500 cps.
Muscle‐fiber architecture, innervation, and histochemistry in the diaphragm of the cat
Authors: Gordon D. C. , Hammond C. G. M. , Fisher J. T. , Richmond F. J. R.
Published: February 2005

Previous anatomical descriptions of the diaphragm have contained several contradictory findings. To validate and extend the previous work, diaphragmatic architecture, histochemistry, and end‐plate distribution were examined by use of a combination of anatomical methods, including fiber microdissections, cholinesterase staining, and enzyme histochemistry. Microdissections showed that musclefiber fascicles throughout the diaphragm contain both long fibers that run from origin to insertion and shorter fibers with intrafascicular terminations. Fibers with intrafascicular terminations were particularly common in the costal diaphragm, where they accounted for the majority of sampled fibers. The heterogeneity of fiber length was reflected in the pattern of end‐plate banding. Cholinesterase studies showed that fiber fascicles in cat and kitten diaphragms were crossed by two to four end‐plate bands distributed in discontinuous arrays across the width of the muscle. A similar pattern of multiple banding was also demonstrated in the adult and neonatal dog. However, rat and rabbit diaphragms had only a single, continuous end‐plate band. Histochemical studies of fiber types in different parts of the feline diaphragm showed that costal, crural, and sternal subregions had similar overall proportions of fiber types. However, type SO (slow oxidative) fibers were distributed more densely on the thoracic than the abdominal surface of costal and crural, but not sternal subregions. Type SO fibers were also concentrated in fiber fascicles bordering the esophageal hiatus.
Maturation of glomerular size distribution profiles in domestic fowl (Gallus gallus)
Authors: Wideman Robert F.
Published: February 2005

Previous histological evaluations of chick kidneys indicated nephrons continue to develop from embryonic foci for up to 6 weeks after hatching. The present study was conducted using an in vivo alcian blue staining technique to quantify posthatch changes in glomerular numbers and sizes in female domestic fowl at 1, 3, 5, 9, 12, 21, and 30 weeks of age. Changes in glomerular size distributions reflect changes in the heterogeneous nephron populations of avian kidneys. Foci of embryonic tissue were observed at the periphery of renal lobules up to 12 weeks of age. Glomerular numbers increased from 69,800/kidney at 1 week to 586,000/kidney at 12 weeks, with no further significant increase up to 30 weeks (599,000/kidney). The increase in glomerular number per gram kidney weight remained constant as kidney mass increased up to 12 weeks of age, after which the number of glomeruli per gram kidney weight declined significantly as kidney size increased without further addition of new nephrons. Glomerular size distribution profiles were constructed using eleven circumference categories. The peak number of glomeruli fell within the 0.11–0.14 mm category at 1 and 3 weeks; within the 0.15–0.18 mm category at 5, 9, and 12 weeks; and within the 0.19–0.22 mm category at 21 and 30 weeks. One and 3‐week‐old chicks had no glomeruli within the largest (⩾0.35 mm circumference) size categories, and 9–12‐week‐old birds had significantly fewer glomeruli in these categories than 21–30‐week‐old birds. These results demonstrate that posthatch renal maturation in domestic fowl involves the ongoing formation of new nephrons up to 12 weeks of age, with subsequent kidney growth (12–30 weeks of age) accomplished by enlargement of existing nephrons (nephron hypertrophy). The cumulative evidence indicates that nephrons destined to develop loops of Henle (mammalian‐type) develop first, with shorter (reptilian‐type) nephrons developing later as the kidneys enlarge.
Fine structure of the filiform papilla of beagle dogs
Authors: Iwasaki Shin‐Ichi , Miyata Ken
Published: February 2005

Light and electron microscopic examination of the dorsal lingual epithelium of beagle dogs (Canis domesticus) revealed three different regions: that anterior to the filiform papillae, that posterior to the papillae, and an interpapillary region. Whereas the basal and suprabasal cells are similar throughout, differences characterize the intermediate and surface layers. Keratohyalin granules are common in the intermediate layers in the anterior and interpapillary regions, tonofibrils are prominent in the posterior region, and no keratohyalin granules occur. The surface layer of the interpapillary region is not keratinized, that of the anterior region shows soft keratinization, and that of the posterior region shows hard keratinization. The perimeter of keratohyalin granules is composed of ribosomes 10–20 nm in diameter.
Neural elements in the cruciate ligaments and menisci of the knee joint of the American alligator, Alligator mississippiensis
Authors: Wink Carole S. , Elsey Ruth M. , Onge Michele St. , Zimny Marilyn L.
Published: February 2005

Knee joints from adult, juvenile, hatchling, and embryonic (full term) American alligators were dissected to reveal the cruciate ligaments and the medial and lateral menisci. Two anterior cruciate (major and minor), a posterior cruciate, an intermeniscal, and a meniscofemoral ligament were identified. In addition, we found a fourth internal ligament which has not been reported previously. Menisci and ligaments from left knees were fixed in formalin and processed for routine histological observation. Those from right knees were stained in bulk by using a gold chloride method and were either frozen and sectioned at 100 m̈m on a sliding microtome or were processed for paraffin sections at 30 m̈m. The morphology of the collagenous, cartilaginous, and vascular constituents of the tissues was similar to that of the dog, cat, and human. Nerve fibers were observed in all tissues sampled. Structures resembling Golgi tendon organs and Pacinian corpuscles were identified, reinforcing the theory that neural elements within cruciate ligaments and menisci may provide afferent input that affects the function of the knee joint.
Anatomy and innervation of the abdominal segmental muscles in larval and adult Tenebrio molitor (Coleoptera)
Authors: Kalogianni E. , Consoulas C. , Theophilidis G.
Published: February 2005

The external morphology, musculature, and the innervation of the abdominal segments were examined in larvae and adult Tenebrio molitor. In the larva, there are 26 pairs of muscles arranged at four different levels in the ventral, lateral, and dorsal region of each segment. In the adult, the number of muscles has been dramatically reduced and is limited to six pairs of muscles located at the dorsal and lateral region of the segment. These muscles, in either larval or adult stages, are innervated by two main nerves, n1 and n2, which originate from the segmental ganglia. The cell bodies of the motoneurons innervating the muscles of the 3rd abdominal segment are located in the 3rd and 2nd abdominal ganglia. Some cell bodies are retained throughout metamorphosis, but others disappear during the larva‐pupa transition.
Ultrastructural changes in micropylar cells and formation of the micropyle during oogenesis in the medaka Oryzias latipes
Authors: Nakashima S. , Iwamatsu T.
Published: February 2005

Ultrastructural changes in differentiating micropylar cells and in the micropyle occur during oogenesis in the medaka, Oryzias latipes. A micropylar cell is not detectable in previtellogenic ovarian follicles. In the early vitellogenic phase, the micropylar cell becomes differentiated from neighboring granulosa cells by its electrondense cytoplasm. The micropylar cell in this phase characteristically displays an increase in rough endoplasmic reticulum, Golgi complexes, and tonofilaments around the nucleus. By the late vitellogenic phase, the enlarged micropylar cell extends a broad cytoplasmic process to the oocyte surface. A conspicuous feature of the process is a large bundle of microtubules oriented perpendicular to the oocyte surface. The inner surface of the micropylar canal has a spiral structure and is covered with the outermost layer of the chorion. In the postvitellogenic phase, the main cell body possesses many tonofilaments, mitochondria, Golgi complexes, and rough endoplasmic reticulum, and the winding cytoplasmic process contains a twisted large bundle of microtubules with a bundle of tonofilaments as its core. The spiral structure of the micropylar vestibule and the micropylar canal reflects the twisting associated with elongation of fibrous bundles of the micropylar cell anchored on the chorion at the animal pole of the oocyte.
Early embryonic development and external features of developing embryos of the caddisfly, Nemotaulius admorsus (trichoptera: Limnephilidae)
Authors: Kobayashi Yukimasa , Ando Hiroshi
Published: February 2005

Formative processes of the blastoderm, germ disk, embryonic membranes, and germ band in the trichopteran Nemotaulius admorsus are described. Successive external changes of developing embryos are also described, chiefly on the basis of SEM data.

The blastoderm is very thin, and a circular germ disk forms in its ventro‐posterior region about 32 hr after oviposition. Embryonic membranes are completed by fusion of amnio‐serosal folds extending from the margin of the germ disk. The germ disk then differentiates into a long germ band in situ. This process is similar to that of other trichopterans of the suborder Integripalpia (e.g., Neophylax concinnus and Neoseverinia crassicornis), but differs from that of Stenopsyche griseipennis (suborder Annulipalpia) in which the germ band and embryonic membranes are formed by deep invagination of the germ disk.

The germ band or embryo, as in other trichopteran species, assumes a completely superficial position throughout development. The following description summarizes its external differentiation. An egg tooth develops at the top of the head capsule. Antennal rudiments become small as development advances. In the maxillary segment, the lacinial and galeal lobes are indistinguishable and united into one laciniogaleal complex. Thoracic appendages develop considerably during the embryonic period. Pleuropodia are formed in the first abdominal segment. Two pairs of appendage‐like swellings, a ventral and a medial pair, arise in each of the first eight abdominal segments, and homologies of these swellings and pleuropodia are discussed. Terminal hooks originate from the bilateral projections of the telson. Tracheal invaginations appear in the mesothoracic, metathoracic, and the first eight abdominal segments, but their openings or spiracles close later. Embryonic membranes rupture after revolution, and thus the secondary dorsal organ is formed.
Oral papillae of adults of the southern hemisphere lamprey Geotria australis
Authors: Cook R. D. , Hilliard R. W. , Potter I. C.
Published: February 2005

The morphology, cell types, and innervation of the several small papillae (x̄ = 17) and two larger papillae, which together form a ring just outside the fimbriae surrounding the suctorial disc of adult Geotria australis, have been studied using various histological stains, including silver impregnation, and scanning and transmission electron microscopy. The epithelium of all papillae consists almost entirely of mucigenic cells. The multivillous and oligovillous cells, which are found elsewhere in the lamprey epidermis, were not observed, and Merkel and polyvillous cells are rare. Free nerve endings are common, however, in the basal layers of the epidermis. Unlike the small papillae, the two large papillae contain a core of skeletal muscle and a prominent layer of dermal collagen. In the submucosa of these large papillae, the nerves form a dense, compact layer that contains many large and probably sensory axons. It is suggested that the oral disc papillae of adult G. australis are encapsulated mechanosensory structures that play a role in enabling the animal to locate and attach to a suitable point on host fishes or other surfaces.
Breeding and post‐breeding structure of the vas deferens of the long‐toed salamander Ambystoma macrodactylum
Authors: Zalisko Edward J. , Larsen John H.
Published: February 2005

The vas deferens of Ambystoma macrodactylum is composed of a peritoneal epithelium, connective tissue layer with fibroblasts, circular smooth muscle, capillaries, cells containing lipid, and a luminal epithelium composed of a single layer of cuboidal cells covered by a net of interconnected ciliated squamous cells. The cuboidal cells have abundant rough endoplasmic reticulum, mitochondria, and PAS + secretory vesicles. Squamous cells of breeding males consistently have tufts of ∼100 cilia located at one end of the long axis of each cell. These cilia may help distribute secretory products. The squamous cells, absent in post‐breeding males, are apparently sloughed into the lumen. Lipid vesicles are present throughout the cytoplasm of the cuboidal and squamous epithelial cells and are also in some cells of the connective tissue layer. These vesicles increase dramatically in number during the first 4 weeks after breeding and may serve as an energy pool for the next breeding season. Enzyme‐histochemical tests for testosterone synthesis were negative. In addition to the accumulation of lipid and the loss of squamous cells in the vas deferens, after breeding PAS + vesicle production is terminated. These alterations appear to represent energy conservation strategies employed by the sperm‐depleted vas deferens.
Density of muscle spindle profiles in the intrinsic forelimb muscles of the dog
Authors: Buxton Donald F. , Peck David
Published: February 2005

The concept of parallel muscle combinations, in which spindle density is significantly higher in small muscles compared to their larger counterparts in large‐small muscle combinations acting across a joint, is supported by the results of this study regardless of the joint. Analysis of the canine data as well as previously published guinea pig forelimb and human pelvic limb data revealed no significant difference in spindle density between antigravity and non‐antigravity muscles. Furthermore, a gradual increase in spindle density from proximal to distal on the limb was not found, although spindle density was significantly higher in the intrinsic manus or pes muscles compared to more proximal limb muscles in all three species. The significant differences in spindle densities in parallel muscle combinations and in manus/pes versus proximal muscles are discussed relative to their possible role in the control of locomotion.
Development and evolution of the carotid circulation in geomyoid rodents in relationship to their craniomorphology
Authors: Brylski P.
Published: February 2005

The diversity in cranial morphology of living geomyoids, including pocket gophers (Thomomys), spiny pocket mice (Heteromys and Liomys), desert pocket mice (Chaetodipus and Perognathus), and kangaroo rats and mice (Dipodomys and Microdipodops) is accompanied by only a few differences in their cephalic arterial circulation. The principal difference is the origin of the pterygopalatine artery, which serves the orbit and rostrum. In dipodomyines and perognathines it originates as a stapedial branch of the internal carotid artery and passes through the middle ear en route to the braincase. In geomyines and heteromyines it originates as an internal maxillary branch of the external carotid artery and enters the braincase directly. Either geomyines and heteromyines are convergent in this respect, or the currently recognized family Heteromyidae is paraphyletic. The stapedial artery is the same size in early embryos of T. bottae and D. merriami, but in the former species it fails to grow and disappears in juveniles. Comparison of developmental series of D. merriami and T. bottae revealed that the decline of the artery in the latter species is preceded by a greater degree of arterial coarctation, or narrowing, as it passes though the developing stapes. The loss of the stapedial artery is correlated with an enlarged masseter profundus muscle in T. bottae and with an unusually small stapes in T. bottae, H. desmarestianus, and L. salvini. I hypothesize that the primitive condition for geomyoids is the presence of both stapedial and internal maxillary arteries, that the stapedial artery was lost in geomyines and heteromyines because of the constraint on its size posed by the stapes, and that the stapedial artery was retained in dipodomyines because enlargement of the stapes accompanied bullar inflation in these taxa and lifted the constraint on the size of the stapedial artery.
The cycle of foilicuiar and interstitial cells (Leydig cells) in the testis of the marbled newt, Triturus marmoratus (caudata, salamandridae)
Authors: Fraile Benito , Saez Francisco Jose , Paniagua Ricardo
Published: February 2005

Ultrastructural examination of the marbled newt (Triturus marmoratus) testis throughout the annual cycle revealed that during the period of testicular quiescence (November–February), primordial germ cells proliferate within cords of filament‐rich epithelial cells that will become follicular cells (FCs). Fibroblast‐like cells surround the FCs and form the lobule‐boundary interstitial cells (ICs). During the period of germ cell development from primordial germ cells to round spermatids (March–June), the FCs surrounding the developing germ cells contain scanty cytoplasm with abundant rough endoplasmic reticulum and scarce filaments. With spermatid elongation (July–August), the FC size grows, its nucleus becomes irregularly outlined, and its cytoplasm displays abundant smooth endoplasmic reticulum, residual bodies, lipid droplets, and large vacuoles. After spermatozoon release by the FCs (August–September), the adjacent ICs increase their size and transform into Leydig cells with abundant smooth endoplasmic reticulum, mitochondria with tubular cristae, and lipid droplets. During the period of testicular quiescence (November–February), the Leydig cells undergo involution, eventually developing the morphological attributes of mesenchymal cells. Intermingled among these cells, cords of filament‐rich cells are observed. During this period of the cycle, spermatozoon cysts supported by FCs are present. At the beginning of the germ cell proliferation period (March), these spermatozoa arc released, and the adjacent ICs undergo a transformation into Leydig cells similar to those observed in August‐September. Maturation and involution of ICs occur when testosterone levels are known to be rising and falling, respectively.