bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure and organization of circumventricular organs and endolymphatic tubules in the treefrog, Hyla versicolor
Authors: Kemnitz Christopher P. , Fox Linda M. , McNulty John A.
Published: February 2005

The morphology and anatomical relationship of the paraphysis, anterior choroid plexus, and endolymphatic tubules of Hyla versicolor suggest that these structures may act as a functional unit to regulate composition of the cerebrospinal fluid (CSF). Ependymal cells of both the paraphysis and the choroid plexus exhibit ultrastructural features (an extensive microvillar border, large intercellular spaces containing an amorphous material, and apically located mitochondria) which indicate active exchange between the blood and CSF. Mast cells (which may play a role in regulating vascular permeability) also occur on the brush border. The tubules of the endolymphatic sacs were found to lie in close relation with the dorsal portion of the paraphysis. The endolymphatic organ is known to play a role in systemic buffering during respiratory acidosis and may influence Na/K fluxes via calcium release. The association of the paraphysis with the endolymphatic tubules may therefore represent an important mechanism for ion regulation in the CSF of amphibians. The ultrastructure of the pineal organ agrees with descriptions for other species. No pineal stalk was present. Photoreceptor inner and outer segments project into a central lumen continuous with the third ventricle. Outer segments show signs of disorganization. Photoreceptor/neural dendrite contacts involve synaptic ribbons and conventional synapses.
Eye structure of Ophryotrocha puerilis (Polychaeta: Dorvilleidae)
Authors: Rhode Birgit
Published: February 2005

The protandric hermaphrodite Ophryotrocha puerilis possesses one pair of eyes. They are located in the peristomium. Each light‐sensitive organ consists of one sensory cell and one to two supporting cell(s) embedded in a cup‐shaped reflector. The sensory‐supporting cell complex is enveloped by a basal lamina. This lamina is supposed to be identical with the neural lamella. Thus the eyes proper have to be regarded as protrusions from the brain, while epidermal cells seem to differentiate to crystalline cells (reflector) and are deposited onto the sensory complex.

The reflector is built up by several cup‐shaped cells (juveniles, 4–5; adults, 10–12). Each of these cells comprises a multilayer of parallel‐oriented, membrane‐bound crystalline platelets which are thought to be guanine. The sensory cell is of the inverted rhabdomere type. Submicrovillar cisternae, typical for most polychaete eyes, are lacking. The first and always present supporting cell entirely envelops the sensory cell, thus forming the extracellular space around the rhabdomere. It does not contain any pigment granules. Often but not always a second supporting cell has been observed surrounding the sensory cell and first supporting cell. It is interpreted as a glial cell.

In the sensory cell beneath the rhabdomere, pino‐ and phagocytosis can be observed and secondary lysosomes are found in high densities. Preliminary results seem to demonstrate that there is no distinct diurnal cycle of receptoral membrane recycling. In comparison with the ocelli of Dinophilidae, which have been interpreted as a dorvilleid‐related family, morphological differences and their application to phylogenetic considerations are discussed.
Innervation pattern of the gill arches and gills of the carp (Cyprinus carpio)
Authors: de Graaf Paul J. F.
Published: February 2005

The innervation pattern of the respiratory gill arches of the carp (Cyprinus carpio) is described. The gill region is innervated by the branchial branches of the glossopharyngeal and vagal nerves. Each branchial nerve divides at the level of or just distal to the epibranchial ganglion into: 1) a pretrematic branch, 2) a dorsal pharyngeal branch, and 3) a posttrematic branch. The dorsal pharyngeal branch innervates the palatal organ in the roof of the buccal cavity. The pretrematic and posttrematic branches innervate the posterior and anterior halves, respectively, of the gill arches bordering a gill slit. Each branch splits into an internal and an external part. The internal bundle innervates the buccal side of the gill arch, including the gill rakers. The external bundle terminates in the gill filaments. The epibranchial motor branch, a small nerve bundle containing only motor fibers, circumvents the ganglion and anastomoses distally with the posttrematic branch. The detailed course and branching patterns of these branches are described.
Light microscopic and ultrastructural study of the development of the saccus vasculosus in the rainbow trout, Oncorhynchus mykiss
Authors: Corujo Asuncion , Rodríguez‐Moldes Isabel , Anadón Ramon
Published: February 2005

This study using light and electron microscopy indicates that the saccus vasculosus is distinguishable in 9‐mm embryos and grows continuously throughout embryonic development to the adult stage. In the saccus vasculosus, epithelial mitoses are observed in all stages studied. Phases of centriologenesis, ciliogenesis, and globule formation have been characterized in developing coronet cells. During the phase of centriologenesis, new centrioles appear in association with pre‐existing centrioles and not on deuterosomes. After ciliogenesis, each cilium differentiates to a globule almost at the same time as the other cilia of the coronet cell. The inner membrane system of the globules seems to derive from the ciliary plasma membrane. This membrane system often produces membrane whorls during the development. The different phases of coronet cell development have been found in the same individual and in all the stages studied except the 9‐mm embryo. Cerebrospinal fluid‐contacting neurons are observed in the saccus epithelium from the 12‐mm embryos on and are distinguishable from coronet cells in their early formative stages. The three cell types of the saccus vasculosus increase continuously in number during development. Nerve processes are found in the saccus vasculosus of embryos, whereas differentiated synapses appear later in the fry. The significance of continued coronet cell formation is discussed in relation to a putative coronet cell and/or a globule renewal cycle in the adult.
The mechanism of dewlap extension in Anolis carolinensis (Reptilia: Iguanidae) with histological analysis of the hyoid apparatus
Authors: Bels Vincent L.
Published: February 2005

Anolis carolinensis has two aggressive displays involving movements of the hyoid apparatus: erection of the throat and extension of the dewlap. Erection of the throat is an enlargement of the gular region and dewlap extension consists of a vertical erection of the gular flap. Cinefluoroscopy and high speed cinematography show that the dewlap is extended in three phases: 1) protraction of the entire hyoid apparatus; 2) forward pivoting movement of the ceratobranchials II; and 3) retraction of the ceratobranchials II and the entire hyoid apparatus. The cartilaginous elements of the hyoid apparatus are variably mineralized. The entoglossal process and the hypohyals are the most calcified elements. The mineralized portion of the hyoid body, to which the other elements articulate, presents a complex pattern. The calcification of entoglossal process and the hypohyals stop just where they are fused with the hyoid body. The hyoid body presents four mineralized masses, two central corresponding to the base of the ceratobranchials II and two lateral being the head of the ossified ceratobranchials I. The lateral masses articulate on the central masses by a synovial joint. Morphologically, the ceratobranchials II form the hyoid body and become separated at the mid length of the synovial articulation of the ceratobranchials I and the hyoid body. The calcified matrix of the ceratobranchials II gradually changes from a large calcified mass (within the hyoid body) to a semicircle, opened ventrally, which permits their bending during dewlap extension. The highly mineralized posterior tip of the entoglossal process and the hyoid body serve as a pivot to pivoting forward movement of the ceratobranchials II producing at the change of the pattern of mineralization. Forward movement of the ceratobranchials II is produced by electrical stimulation of the M. branchio hyoideus. The opposition of the throat skin to the movement of the ceratobranchials II produces the bending of those longest elements. Electrical stimulation of the hyoid muscles confirms the key role of M. branchiohyoideus during dewlap extension. Simultaneous contractions of all the hyoid and extrinsic tongue (retractor and protractor) muscles with the M. branchiohyoideus during dewlap extension may be a possible motor pattern for dewlap extension in Anolis lizards.
Seasonal variations in oviductal morphology of the painted turtle, Chrysemys picta
Authors: Motz Vicki Abrams , Callard Ian P.
Published: February 2005

Histology of each of the five segments of the oviduct of the female turtle Chrysemys picta was described for successive intervals throughout their annual cycle. Uterine and glandular segments showed marked seasonal variations in the extent and content of the submucosal and epithelial glands. Submucosal glands were most prominent in preovulatory and postovulatory animals (May to June), regressing in late summer (oviposited animals) and recrudescing the following spring. These changes correlated with variations in the muscularis layer, the number of uterine epithelial blebs, oviductal vascularity, and the presence of eosinophils in cervical segment cross‐sections. These cyclic seasonal changes are discussed in relationship to reported seasonal changes in gonadal steroids in this species. Hormonal control was corroborated by oviductal response to estradiol‐17β injected (1 mg/kg daily for 2 weeks) into mature, reproductively inactive (winter) animals. This treatment induced increases in glandular activity, vascularity, and distribution of eosinophils comparable to those of reproductively active (summer) animals.
Topography and nerve supply of the cucullaris (trapezius) of skates
Authors: Boord Robert L. , Sperry David G.
Published: February 2005

Dissections of Sudan black B stained specimens reveal that, of a complex of medial, intermediate, and lateral muscles of skates, presumed homologous to the cucullaris of sharks, only the lateral muscle is innervated by a branch or branches of the vagus and is inserted, in part, to the fused pharyngobranchials of the caudal visceral arches. The medial and intermediate muscles are supplied by separate branches of rostral spinal nerves and do not attach to the branchial skeleton. The lateral muscle therefore is the most likely homologue of the cucullaris (trapezius) of sharks and perhaps other fishes and tetrapods. The medial and intermediate muscles appear to be part of the axial musculature.
Presence of cells and fibers immunoreactive toward antibodies to different peptides or amine in the digestive tract of the snailHelix aspersa
Authors: Marchand C. R. , Colard C.
Published: February 2005

An immunocytological study of four different parts of the gut of Helix aspersa clearly demonstrates the presence of many cells and fibers immunoreactive toward antibodies directed to vertebrate (α, β‐endorphin, α, β‐MSH, ACTH 1–24 and ACTH 17–39, met‐enkephalin, somatostatin, insulin, glucagon, P.P., serotonin) or invertebrate (FMRF‐amide) peptides.

These results are evidence of the presence of different substances related to known peptides or amines in the epithelial and connective tissue cells and nerve fibers of the snail gut. Immunocytochemistry may help to elucidate the morpho‐functional characteristics of the enteroendocrine cells of H. aspersa.
Configuration of the medial and lateral segments of duck (Anas platyrhynchos) salt glands
Authors: Butler David G. , Youson John H. , Campolin Elizabeth
Published: February 2005

Salt glands of the domestic duck Anas platyrhynchos differ from those of the herring gull Larus argentatus and other birds. In ducks, each salt gland consists of distinct medial and lateral segments. Centrally located drainage ducts that extend along the entire length of these medial and lateral segments collect hypertonic fluid secreted by an array of lobules. Each lobule is formed by a single mass of branched tubules in which the direction of capillary blood flow is opposite to that of the secreted fluid. This fluid drains from the medial segment through an external duct that opens into the nasal cavity at the base of the vestibular fold. A duct from the lateral segment loops and opens onto the surface of the nasal septum. The structure and function of the secretory cells is reviewed briefly within the context of our study of the configuration of duck nasal salt glands.
Volumetric measurements do not demonstrate that the spider brain “central body” has a special role in web building
Authors: Weltzien Peter , Barth Friedrich G.
Published: February 2005

The results of volumetric measurements led Hanström ('28) to suggest that specialized neuropil in the brain, the so‐called central body (CB), may be of particular importance in the nervous control of web building behavior in spiders. We compared the volumes of the various brain regions in four spider species clearly differing in lifestyle and web building behavior: an orb weaver (Nephila clavipes), a wandering spider (Cupiennius salei), a jumping spider (Phidippus regius), and a bird spider (Ephebopus sp.). Our results obtained in adult animals as well as our observations on the postembryonic development of the brain do not support Hanström's hypothesis. The relative share of the CB in the brain is very similar in all four species (ca. 3.1 to 5.1%). The differentiation of the CB into a clearly demarcated two‐lobed structure does not coincide with the onset of web building behavior in Nephila. The CB of both Nephila and Cupiennius is already clearly recognizable in spiderlings which have not even left the egg sac.
Hyoid morphology and movements relative to abducting forces during feeding in Astatotilapia elegans (Teleostei: Cichlidae)
Authors: Aerts Peter
Published: February 2005

In fishes, the abducting hyoid bars push the suspensoria outwards. This force transmission is generally assumed to be important during fast suction feeding (strenuous activity). In Astatotilapia elegans the hyoid symphysis can best be modelled as an oblique hinge. The relevance of this hinge morphology on the force transmission has been studied by means of a three‐dimensional (3D) model simulating the displacements of the hyoid‐suspensorial system. It appears that the transmission force factor increases throughout feeding in the case of the hinge model. Reduction of the hyoid symphysis to a point articulation (as was done formerly in attempts to quantify the transmission by means of planar models) suggests an unfavourable decline of the transmission force to zero during maximal mouth expansion. The angle between the hinge axis of the symphysis and the longitudinal axis of the hyoid bar is 45°. Such a configuration allows for a maximal increase in the volume of the buccal cavity for suction. This functional aspect, together with the apparent maximization of the force transmission during feeding, suggests that constructional and neuromotoric factors have been improved during the evolutionary development of the hyoid‐suspensorial system.
Axial and paraxial influences on limb morphogenesis
Authors: Stephens Trent D. , Spall Richard , Baker Wallace C. , Hiatt Scott R. , Pugmire Douglas E. , Shaker Mohammad R. , Willis Howard J. , Winger Kirk P.
Published: February 2005

Previous studies by Stephens and McNulty and Strecker and Stephens have demonstrated that foil barriers placed between the mesonephros and lateral plate at stages 12 to 15 inhibited limb development, but foil barriers placed between the neural tube and somites at stages 11 to 12 resulted in limbs with normal skeletal patterns. It was concluded that some influence present in the paraxial region of the embryo at stages 11 to 15 is necessary for normal limb development. The present study was undertaken to localize that influence more precisely. Foil barriers were placed in the lateral edge of the somites or segmental plate of stage 10 to 15 chick embryos. Barriers placed into stage 13 to 15 embryos resulted in chicks with normal limbs, but barriers placed into stage 10 to 11 embryos resulted in chicks with defective limbs. Barriers inserted just lateral to Hensen's node at stages 6 to 8 resulted in embryos with defective or absent wings. We also grafted stage 4 to 9 presumptive limb territories with and without Hensen's node. Explants without Hensen's node formed limb‐like structures in 1% of the cases. Explants with Hensen's node formed limb‐like structures in 27% of the cases. When barriers were implanted and a node was placed on the lateral side of the barrier, limbs formed in 40% of the cases. These data suggest a medial to lateral progression of some as yet unknown morphogenetic influence necessary for normal limb development and we hypothesized that the influence may initially emanate from Hensen's node.
Localization and transport of lipids in the avian ovarian follicular layers and the structural relationship of theca and granulosa to the basement membrane
Authors: Callebaut Marc , D'Herde Katrien , Hermans Nancy , Van Nassauw Luc
Published: February 2005

We describe the localization of lipids in the wall and superficial ooplasm of the largest avian ovarian follicles by the use of different fixatives and light and electron microscopy. We demonstrate that each yolk globule is always accompanied by one or more highly osmiophilic and sudanophilic alcohol insoluble yolk masses, which we have called satellite yolk. Together with the protein containing yolk globule it forms an integral morphological part of a compartmentalized, bipartite yolk system. Cytochemical, histoautoradiographic, biochemical, and light and electron microscopical aspects of satellite yolk were studied. At the start of satellite yolk formation in the 3–4 mm diameter follicle (when the oocyte begins to yellow) the distribution of the microcirculation of the follicle wall becomes printed on the underlying superficial ooplasm of the oocyte. The oocyte then presents so‐called yolk mountains (containing satellite yolk), only localized below the thecal capillary sinus and not below the efferent and radially perforating thecal veins (black hole regions). We also describe the structural continuity between the thecal intercellular spaces and the microvilli‐associated extracellular spaces of the granulosa cells via the basement membrane. The thecal cells present centripetal extensions into the basement membrane and the basement membrane material extends centripetally into the granulosa microvillar channels. Therefore, at least two cellular barriers are crossed when fat or fat precursors are transported from the thecal capillary sinus to the ooplasm.
Distribution and expression of two interactive extracellular matrix proteins, cytotactin and cytotactin‐binding proteoglycan, during development of Xenopus laevis. I. Embryonic development
Authors: Williamson David A. , Parrish Elaine P. , Edelman Gerald M.
Published: February 2005

An immunohistochemical study of the localization of cytotactin and cytotactin‐binding (CTB) proteoglycan throughout embryonic development of the anuran Xenopus laevis reveals that both appear in a restricted pattern related to specific morphogenetic events.

CTB proteoglycan expression is first detected during gastrulation at the blastopore lip. Later, it is seen in the archenteron roof around groups of cells forming the notochord, somites, and neural plate. Cytotactin first appears after neurulation, and is restricted to the intersomitic regions. Both molecules appear along the migratory pathways of neural crest cells in the trunk and tail. Later, cytotactin is present at sites where neural crest cells differentiate, around the aorta and in the smooth muscle coat of the gut; CTB proteoglycan is absent from these sites. In the head, cytotactin is initially restricted to the regions between cranial somites, while CTB proteoglycan is distributed throughout the cranial mesenchyme. The expression of both molecules is later associated with key events in chondrogenesis during the development of the skull. After chondrogenesis, CTB proteoglycan is distributed throughout the cartilage matrix, while cytotactin is restricted to a thin perichondrial deposit. Both molecules are expressed in developing brain.

These findings are compared to studies of the chick embryo and although distinct anatomical differences exist between frog and chick, the expression of these molecules is associated with similar developmental processes in both species. These include mesoderm segmentation, neural crest cell migration and differentiation, cartilage development, and central nervous system histogenesis.
Osteology, skeletal development, and chondrocranial structure ofHamptophryne boliviana(Anura: Microhylidae)
Authors: de Sá Rafael O. , Trueb Linda
Published: February 2005

Hamptophryne bolivianais a medium‐sized microhylid frog inhabiting the forest‐floor leaf litter of South American rainforests. Larvae of this species typically are found near the bottom of small ponds and water‐filled depressions in the forest. On the basis of cleared‐and‐stained specimens, the larval chondrocranium is described, as well as the development of the skeleton and its condition in adults. Contrary to previous reports, adultHamptophryne bolivianapossess neopalatine (= palatine) bones. The vomer is divided into anterior and posterior parts; the degree of development of the posterior vomers varies among individuals and bilaterally within individuals. In its osteological development,Hamptophrynediffers from most other anurans studied in that the vomer, and bones of the suspensorium and mandible, appear postmetamorphically. Similarly, the ischium, pubis, carpals, and tarsals do not appear until metamorphosis is completed. The chondrocranium possesses paired suprarostral cartilages—elements that have been reported to be absent in microhylid larvae. Furthermore, the chondrocranium differs from those described for other microhylid taxa by the possession of 1) a subpalatoquadrate bar that is described herein and 2) a greatly expanded, fenestrate sheet of cartilage associated with the larval otic process and otic capsule.
Bizarre flagellum of thrips spermatozoa (Thysanoptera, Insecta)
Authors: Dallai R. , Afzelius B. A. , Lanzavecchia S. , Bellon P. L.
Published: February 2005

The flagellum of the thysanopteran spermatozoon has been examined by electron microscopy and computer‐aided image analysis. The flagellum consists of 27 microtubular elements that probably are formed as outgrowths from three separate basal bodies. Nine of the elements are normal microtubular doublets that carry dynein arms and nine are doublets without dynein arms. The remaining nine elements are microtubular singlets that apparently bear dynein arms and have the same appearance as A‐subtubules of microtubular doublets. The 27 elements are arranged in a fixed pattern that consists of nine groups, each of which begins with a microtubular singlet and ends with an arm‐less microtubular doublet. Computer‐aided image analysis has shown that the A‐subtubules of the doublets and the microtubular singlets have lumens with very similar patterns. The sperm tail is known to have some motility; it generates fast waves running along its length. The amalgamated axonemes hence act as a functional flagellum. The thysanopteran sperm tail is the only type of flagellum known to us that consists of microtubules in a highly asymmetric array.
Evolution of locomotion in arachnida: The hydraulic pressure pump of the giant whipscorpion, Mastigoproctus Giganteus (Uropygi)
Authors: Shultz Jeffrey W.
Published: February 2005

Many arachnids lack extensor muscles at the femoropatellar (knee) joint of their legs and extend this joint with hydraulic pressure during locomotion. Pressure is generated through compression of the prosoma, but there is disagreement about which muscles are involved in this process. Many arachhnologists consider contraction of the musculi laterales, a group of modified extrinsic leg muscles, as the cause of high prosomal pressure and regard hydraulic extension as a derived feature. However, integration of results from phylogenetic and comparative anatomical studies supports the view that hydraulic extension is primitive in Arachnida and that fluid pressure is generated by contraction of endosternal suspensor muscles.

The functional predictions of the musculi laterales and endosternite hypotheses were tested by measuring muscle activity and prosomal pressure during unrestrained locomotion in a primitively “extensorless” arachnid, the giant whipscorpion. The results corroborate the endosternite model and refute the musculi laterales model. Changes in the prosomal pressure baseline were correlated with changes in endosternal muscle activity, while the musculi laterales fired in a step‐coupled pattern of discrete bursts that appeared to be incapable of generating the pressure observed during locomotion. Step‐coupled fluctuations in prosomal pressure were observed but were apparently caused by rapid flexing of the femoropatellar joints of the fourth leg pair rather than contraction of the musculi laterales.
Functional analysis of a specialized prey processing behavior: Winnowing by surfperches (Teleostei: Embiotocidae)
Authors: Drucker Eliot G. , Jensen Jeffrey S.
Published: February 2005

Several surfperches (Embiotocidae), including the black surfperch, Embiotoca jacksoni, exhibit a specialized prey handling behavior known as winnowing, in which ingested food and non‐nutritive debris are separated within the oropharyngeal cavity. Prey items are swallowed, and unpalatable material is ejected from the mouth. Winnowing is believed to play an important role in the partitioning of food resources among sympatric embiotocids. We present a mechanistic model for this separative prey processing based on high‐speed video analysis, cineradiography, electromyography, and buccal and opercular cavity pressure transducer recording.

Winnowing by embiotocids is characterized by premaxillary protrusions repeated cyclically with reduced oral gape. Protrusion is accompanied by depression of the hyoid apparatus and adduction of the opercula. Alternating expansion and contraction of the buccal and opercular cavities generate regular pressure waveforms that indicate bidirectional water flow during processing. Separation of food from debris by Embiotoca jacksoni occurs in three phases. The prey‐debris bolus is transported anteriorly and posteriorly within the oropharyngeal cavity and is then sheared by the pharyngeal jaws. Mechanical processing is complemented by the rinsing action of water currents during hydraulic prey transport.

The feeding apparatus of Embiotoca jacksoni is functionally versatile, although not obviously specialized relative to that of nonwinnowing surfperches. Protrusion of the premaxillae and depression of the hyoid apparatus are critical to both prey capture and subsequent prey processing. The pharyngeal jaws exhibit kinematic patterns during separation of food from debris distinct from those observed during mastication of uncontaminated prey. This behavioral flexibility facilitates resource partitioning and the coexistence of E. jacksoni in sympatric embiotocid assemblages.
Fractal analysis of sagittal suture morphology
Authors: Hartwig Walter Carl
Published: February 2005

Quantifying shape is a broad problem in the morphological sciences. Most techniques for numerically describing shape abstract the shape into the most logical ideal Euclidean dimension. The fractional, or fractal, dimension is a simple computation that expresses shape in real, rather than ideal, space. The structured walk technique developed for the fractal analysis of rugged boundaries is applied here to the contour of the human sagittal suture in order to discriminate the separate morphological patterns of interfingering and interlocking. These attributes contribute differentially to the suture's “complexity,” a concept often used in biomechanical hypotheses. Previous techniques for estimating sutural complexity do not isolate small‐scale from large‐scale morphological patterns. Results indicate that despite the visual appearance of great variation, human sagittal sutures are remarkably consistent in the degree of complexity expressed separately by large‐scale interfingering lateral excursions and small‐scale interlocking ruggedness. There is no significant correlation between the absolute or bregma‐lambda chord length of the human sagittal suture and its degree of complexity as determined by the structured walk technique.
Internal reproductive system in adult males of the genus Camponotus (Hymenoptera: Formicidae: Formicinae)
Authors: Wheeler Diana E. , Krutzsch Philip H.
Published: February 2005

Descriptions are provided of the histology and ultrastructure of the male internal reproductive tracts from three species of Camponotus, representing three subgenera. This study is the first to provide ultrastructural information on the testes (including spermatogenesis and spermiogenesis), seminal vesicles, and accessory glands in ants. Testes contain about ten follicles each, and each follicle is capable of producing hundreds of cysts in which spermatozoa develop. Structural evidence of meiosis in late pupal testes includes cytoplasmic bridges between spermatocytes, centriole elimination, and fusion of mitochondria. Developing spermatids are in close contact with cyst cells in the region of the acrosome. Mature spermatozoa are similar in ultrastructure to those described previously for two other subfamilies of ants (Myrmicinae and Dolichoderinae). The ultrastructure of the seminal vesicle suggests that it is not merely a passive organ for sperm storage. Large numbers of both mitochondria and membranous whorls suggest a pH‐regulating and/or hormonal function. The accessory gland is made up of secretory cells that contain a diversity of secretory granules. SDS‐PAGE reveals several proteins found in the accessory glands but absent in the adjacent genitalia. Preliminary analyses indicate that carbohydrate is an important component of accessory gland secretions.
Figures of Eberth in the amphibian larval epidermis
Authors: Fox Harold
Published: February 2005

Figures of Eberth are prominent extensive filamentous structures in the basal epidermal cells of larval amphibians. They are compared and contrasted qualitatively and quantitatively in a number of species of the three groups of living amphibians.

Fully developed Figures consist of massive skeins of tonofilaments oriented in three dimensions and hinged on hemidesmosomes within the cell. The overall appearance of the Figures is similar in anurans, urodeles and Ichthyophis among the apodans. However, in terms of size and number per unit length of the proximal cell margin, the hemidesmosomes and the thickness or their emergent skeins in anurans and Ichthyophis differ significantly from those parameters in urodeles, a feature that is presumably independent of cell size. Figures are poorly developed or missing in embryos of Typhlonectes, which has no larval stage in its life history.

These ubiquitous skeletogenous structures in the aquatic larval amphibians, among other things, could be protective of underlying delicate tissues and act as a stabilizer in bodily movement during swimming. They could also serve as a reserve of cytokeratin for use during later cellular division and sloughing.
Electron microscopic structure and innervation of the carotid baroreceptor region in the rock hyrax (Procavia capensis)
Authors: Kimani James Kirumbi
Published: February 2005

Semi‐thin plastic sections reveal that the carotid baroreceptor region in the rock hyrax comprising the origin of the internal carotid artery has a preponderantly elastic structure and a thick tunica adventitia. In contrast, the common carotid artery has a musculoelastic structure, whereas the cranial segment of the internal carotid artery (immediately distal to the baroreceptor areas) shows the features of a muscular artery. Electron microscopy discloses the presence of sensory nerve endings within the parts of the tunica adventitia adjoining the preponderantly elastic zone of the internal carotid artery. These nerve endings are characterized by varicose regions containing a large quantity of mitochondria. Bundles of collagen fibers in the tunica adventitia form convolutions or whorls around the nerve terminals and often terminate on the surface of the elastic fibers or into the basement membranes of the neuronal profiles. The large content of elastic tissue in the tunica media of the baroreceptor region may render the vessel wall highly distensible to intraluminal pressure changes. This, in turn, would facilitate the transmission of the stimulus intensity to the sensory nerve terminals located in the tunica adventitia. It is suggested that the stretching of elastic fibers may form the main mechanical event leading to the distortion of the associated nerve terminals. However, a change in the geometrical configuration of the bundles of collagen under the influence of the elastic fibers may provide a better insight into the mechanisms of distortion of the baroreceptors related to and/or in contact with collagen fibers. © 1992 Wiley‐Liss, Inc.
Ultrastructural and cytochemical aspects of oogenesis in Castrada viridis (platyhelminthes, rhabdocoela)
Authors: Falleni Alessandra , Lucchesi Paolo
Published: February 2005

The heterocellular female gonad of the typhloplanoid Castrada viridis consists of a single germarium and two rows of vitellaria. The germarium, composed of a germinative zone and a growth zone, is surrounded externally by a layer of accessory cells the function of which is hypothesized in this study. The main feature of oocyte differentiation is the synthesis of small electron‐dense inclusions produced by the rough endoplasmic reticulum (R.E.R.) and Golgi complex. The electron‐dense content of the egg inclusions reacts positively to the cytochemical test used to detect polyphenols and is only partially extracted following incubation in protease. The genesis, composition, and peripheral location of egg inclusions in mature oocytes suggest that they could represent residual eggshell granules. The presumed function of eggshell granules is discussed and their fine morphology is compared with that observed in other neoophoran Platyhelminthes. © 1992 Wiley‐Liss, Inc.
Effects of sex steroid implants on reproductive tissues of female garter snakes (Thamnophis sirtalis)
Authors: Whittier Joan M.
Published: February 2005

Female Thamnophis sirtalis were administered intraperitoneal implants of either estradiol 17β (E2), testosterone (T), 5α‐dihydrotestosterone (DHT), or empty silastic capsules for 3 weeks. Plasma levels of E2 and T, measured by specific radioimmunoassay, were significantly elevated in E2 and T‐implanted females when compared to controls. T‐implanted females did not have elevated circulating E2 levels, suggesting that E2 in the plasma normally is not derived from peripheral conversion of T to E2. Implantation of DHT did not significantly change circulating levels of E2, T, or DHT. All three sex steroid—treated groups of animals had increased oviductal mass compared to controls, while hepatic mass of only E2‐treated animals was significantly greater. None of the steroid treatments influenced ovarian mass. Oviductal epithelial cell height and area were greater in the three steroid‐treated groups. Testosterone increased myometrial area while DHT drastically altered oviductal morphology. Hepatic cell area and number increased significantly in E2‐treated females. However, a small increase in both hepatic cell area and number was noted in T‐ and DHT‐treated females as well. These results suggest that androgen in both an aromatizable and non‐aromatizable form can affect the oviduct of females but that the liver primarily responds to estrogenic steroids. © 1992 Wiley‐Liss, Inc.
Sutural complexity in artificially deformed human (Homo sapiens) crania
Authors: Anton Susan C. , Jaslow Carolyn R. , Swartz Sharon M.
Published: February 2005

The pattern of complexity of cranial sutures is highly variable both among and within species. Intentional cranial vault deformation in human populations provides a controlled natural experiment by which we were able to quantify aspects of sutural complexity and examine the relationship between sutural patterns and mechanical loading. Measures of sutural complexity (interdigitation, number, and size of sutural bones) were quantified from digitized tracings of 13 sutures and compared among three groups of crania (n = 70) from pre‐European contact Peru. These groups represent sample populations deformed in (1) anteroposterior (AP) and (2) circumferential (C) directions and (3) an undeformed population. Intergroup comparisons show few differences in degree or asymmetry of sutural interdigitation. In the few comparisons which show differences, the C group is always more interdigitated than the other two while the AP group has more sutural bones. The sutures surrounding the temporal bone (sphenotemporal, occipitotemporal, and temporoparietal) most frequently show significant differences among groups. These differences are related to the more extreme binding of C type deformation and are consistent with hypothesized increases in tension at coronally oriented sutures in this group. The larger number of sutural bones in the AP group is consistent with the general broadening of the cranium in this group and with experimental evidence indicating the development of ossicles in areas of tension. We suggest that so few changes in sutural complexity occurred either because the magnitude of the growth vectors, unlike their direction, is not substantially altered or because mechanisms other than sutural growth modification are responsible for producing the altered vault shapes. In addition, the presence of fontanelles in the infant skulls during binding and the static nature of the binding may have contributed to the similarity in complexity among groups. © 1992 Wiley‐Liss, Inc.
Functional implications of neural canal anatomy in recent and fossil marine carnivores
Authors: Giffin Emily B.
Published: February 2005

A statistical and functional relationship between neural canal anatomy and locomotor mode is demonstrated in living marine mammals of the Order Carnivora. This relationship is interpreted to be the result of differential innervation and territory of musculature involved in generating the six locomotor patterns analyzed. This osteological reflection of a behavioral trait allows prediction of locomotor pattern in extinct genera of closely related taxa. The robust data allow such predictions even when a considerable number of presacral vertebrae are missing in the fossil specimens. In some cases, these predictions conflict with interpretations based solely on limb osteology. © 1992 Wiley‐Liss, Inc.
Structure of recent and fossil mysid statoliths (Crustacea, Mysidacea)
Authors: Wittmann K. J. , Schlacher T. A. , Ariani A. P.
Published: February 2005

Statoliths of 61 Recent species representing all subfamilies of Mysidae were studied with special emphasis on internal structure. In addition 5 samples of fossil statoliths from Miocene deposits were examined. Species of Boreomysinae and Rhopalophthalminae show simple roughly spherical organic statoliths, with setae originating from the sensory cushion and anchored in the statolith with distal branches extending shortly below the surface. All other subfamilies possess mineralized statoliths of greater structural complexity, with differentiation in core and mantle, where each part may consist of up to three layers. Habitus is hemispherical to discoidal. External gross structures are dorsal tegmen, ventral fundus, and the ambitus forming the outer toroidal to semi‐toroidal circumference. Setae penetrate the mantle through mineralic canals and insert on the surface of the core. As suggested by congeneric species of Schistomysis, there is no principal structural difference between statoliths mineralized with fluorite compared to vaterite. However, vaterite statoliths tend to be more often of moruloid appearance and are exceptional by showing a central conical hole (the hilum) or a central cavity in certain forms. These structures are typical of fossil calcite statoliths. In vaterite and fluorite statoliths, the mantle shows radially arranged (= spherulitic) crystal aggregates. Such arrangements are badly preserved in fossil calcite statoliths. In large extant statoliths, concentric structures, mainly in the form of superficial striation and/or concentric microstrata, are visible in coexistence with radial aggregates. Stratification is possibly due to stratified deposition of the nonmineralized gland product, while the spherulitic structure is indicative of subsequent radial growth of crystal aggregates. The structure of accessory fluorite statoliths in the statocyst of Mesopodopsis slabberi leads to the hypothesis that mantle material is formed by secretions of the caudal statocyst gland. After demineralization of fluorite, vaterite and calcite statoliths, an organic template remains showing most essential morphological features of the statolith. From this we conclude that the structure of the statolith is (almost) entirely matrix mediated. © 1993 Wiley‐Liss, Inc.
Variations in the distribution of motor end‐plates in the avian pectoralis
Authors: Gaunt Abbot S. , Gans Carl
Published: February 2005

Most avian muscles consist of serially arranged, overlapping fibers that do not extend the length of the muscle. This condition appears to be plesiomorphic with respect to diapsid reptiles. The presence of this serialfibered architecture is evidenced by bands of stained motor end‐plates (meps) perpendicular to the columns of fibers and dividing each column into a series of “segments.” The avian pectoralis was chosen for a study of variation in the distribution of meps within a single muscle. We report the interspecific variation for 158 specimens in 63 species. We also use additional specimens to examine intraspecific variation.

Setting aside hummingbirds, which have an unique and clearly derived condition, the number of mep bands along a column of fibers near the shoulder falls within a remarkably small range. The number of segments is not obviously related to phylogenetic relatedness or to any characteristic of flight or ecology and is only slightly related to size. The largest specimens do average more segments per column, but there are no trends among small to medium‐sized species, suggesting that there is an upper limit to fiber length. However, the shape of the sternum and pattern of connective tissue in the pectoralis alleviate the need for additional fibers in many large birds. These findings suggest that the architecture of the avian pectoralis is subject to some as yet unexplained selection that stabilizes the number of myofibers and/or motor neurons. The findings provide few clues as to whether the significant factors are phylogenetic, functional, ontogenetic, or some combination of these. © 1993 Wiley‐Liss, Inc.
An ultrastructural study of the dorsal lingual epithelium of the crab‐eating frog, Rana cancrivora
Authors: Iwasaki Shin‐Ichi , Wanichanon Chaitip
Published: February 2005

The amphibian tongue contains two types of papilla which are believed to function in gustation and in the secretion of salivary fluid. Scanning electron microscopy reveals that columnar, filiform papillae are compactly distributed over nearly the entire dorsal surface of the tongue of the frog, Rana cancrivora, and fungiform papillae are scattered among the filiform papillae. Microridges and microvilli are distributed on the epithelial cell surface of the extensive area of the filiform papillae. Light microscopy shows that the apex of each filiform papilla is composed of stratified columnar and/or cuboidal epithelium and its base is composed of simple columnar epithelium. Transmission electron microscopy reveals that most of the epithelium of the filiform papillae is composed of cells that contain numerous round electron‐dense granules 1–3 μm in diameter. Cellular interdigitation is well developed between adjacent cells. On the free‐surface of epithelial cells, microridges or microvilli are frequently seen. Between these granular cells, a small number of ciliated cells, mitochondria‐rich cells and electron‐lucent cells are inserted. In some cases, electron‐dense granules are present in the ciliated cells. At higher magnification, the electron‐dense granules appear to be covered with patterns of spots and tubules. Overall, the morphology and ultrastructure of the lingual epithelium of the three species of Rana that have been studied are quite similar, but they can be easily distinguished from those of Bufo japonicus. Therefore, it appears that lingual morphology is phylogenetically constrained among members of the predominantly freshwater genus Rana to produce uniformity of papillary structure and this morphology persists in Rana cancrivora despite the distinct saline environment in which it lives. © 1993 Wiley‐Liss, Inc.
Land crabs with smooth lungs: Grapsidae, Gecarcinidae, and Sundathelphusidae ultrastructure and vasculature
Authors: Farrelly Caroline A. , Greenaway Peter
Published: February 2005

The highly terrestrial grapsids and gecarcinids and the amphibious sundathelphusids all have large, expanded branchial chambers. The lining of the branchial chambers is smooth and well vascularized, and it functions as a lung. The respiratory membrane and the cuticle lining the lung are extremely thin (200–350 nm). The blood vessels within the lung are formed from connective tissue cells supported by collagen fibres and lined by a basal lamina. The major vessels in the lung are embedded deep in the branchiostegite and lie just beneath the thick outer carapace. These vessels branch towards the respiratory membrane, where they eventually lose their connective tissue coverings to form thin, flattened lacunae directly below the respiratory epithelium. The lacunae (exchange sites) are bordered by specialized connective tissue cells, which either bear microvilli on their apical surface (fimbriated cells) or are very smooth. The respiratory circulation in the lung is very complex, with two portal systems present between the afferent and efferent systems, producing a total of three lacunal exchange beds. Portal systems increase the surface area available for gas exchange. The major distributing vessel in the lung is the branchiostegal vein, which runs along the inner margin of the branchiostegite. The main venous supplies come anteriorly from the infraorbital and ventral sinuses and posteriorly from the procardial sinus. The main collecting vessel is the pulmonary vein, which arises anteriorly and which runs around the ventral perimeter of the branchiostegite before emptying into the pericardial sinus. © 1993 Wiley‐Liss, Inc.