bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunofluorescent studies on titin and myosin in developing hearts of normal and cardiac mutant axolotls
Authors: Erginel‐Unaltuna Nihan , Lemanski Larry F.
Published: February 2005

Homozygous recessive cardiac mutant gene c in the axolotl, Ambystoma mexicanum, results in a failure of the embryonic heart to initiate beating. Previous studies show that mutant axolotl hearts fail to form sarcomeric myofibrils even though hearts from their normal siblings exhibit organized myofibrils beginning at stage 34–35. In the present study, the proteins titin and myosin are studied using normal (+/+) axolotl embryonic hearts at stages 26–35. Additionally, titin is examined in normal (+/c) and cardiac mutant (c/c) embryonic axolotl hearts using immunofluorescent microscopy at stages 35–42. At tailbud stage‐26, the ventromedially migrating sheets of precardiac mesoderm appear as two‐cell‐layers. Myosin shows periodic staining at the cell peripheries of the presumptive heart cells at this stage, whereas titin is not yet detectable by immunofluorescent microscopy. At preheartbeat stages 32–33, a myocardial tube begins to form around the endocardial tube. In some areas, periodic myosin staining is found to be separated from the titin staining; other areas in the heart at this stage show a co‐localization of the two proteins. Both titin and myosin begin to incorporate into myofibrils at stage 35, when normal hearts initiate beating. Additionally, areas with amorphous staining for both proteins are observed at this stage. These observations indicate that titin and myosin accumulate independently at very early premyofibril stages; the two proteins then appear to associate closely just before assembly into myofibrils. Staining for titin in freshly frozen and paraffin‐embedded tissues of normal embryonic hearts at stages 35, 39, and 41 reveals an increased organization of the protein into sarcomeres as development progresses. The mutant siblings, however, first show titin staining only limited to the peripheries of yolk platelets. Although substantial quantities of titin accumulate in mutant hearts at later stages of development (39 and 41), it does not become organized into myofibrils as in normal cells at these stages. © 1994 Wiley‐Liss, Inc.
Microscopic anatomy of pycnogonida: I. Cuticle, epidermis, and muscle
Authors: Fahrenbach W. H.
Published: February 2005

The integument of Pycnogonida (Arthropoda) consists of an epicuticle decorated with tubercles and a filamentous coat, an exocuticle with a small number of ill‐defined layers, and an endocuticle whose numerous layers are composed of conspicuously cross‐banded fibrils. This cuticular periodicity, attributable to cross‐linked chitin, has been observed previously in uncalcified and untanned cuticle of many lower crustaceans, especially branchiopods and copepods, and in scattered examples of thin respiratory or excretory cuticles of other arthropods. It is uniformly present in all representatives of all nine pycnogonid families examined to date. Stomodeal, proctodeal, and arthrodial cuticles are devoid of the endocuticular periodicity. The cuticle is decorated with sensory filaments and setae, but is more noteworthy for a dense coverage by glands, up to 1,400/mm2. Myocuticular junctions have desmosomal fine structure previously found only in chelicerates. Muscle fine structure is that of slow fibers with long sarcomeres and a high actin to myosin filament ratio, except for cardiac muscle, which has short sarcomeres. Among the arthropods, only merostomates resemble the pycnogonids in the lack of fast somatic muscle fibers. Pycnogonids display a hybrid array of fine structural features that variously serve to relate them to some arthropod subphyla and distance them from others. © 1994 Wiley‐Liss, Inc.
Structural color production by constructive reflection from ordered collagen arrays in a bird (Philepitta castanea: Eurylaimidae)
Authors: Prum Richard O. , Morrison Randall L. , Ten Eyck Gary R.
Published: February 2005

Ordered hexagonal arrays of parallel collagen fibers produce the brilliant green structural color of the fleshy, supraorbital caruncles of male Velvet Asity (Philepitta castanea; Aves: Eurylaimidae). The collagen arrays are organized in larger macrofibrils that are packed irregularly within cone‐shaped papillae that cover the surface of the caruncle. The color of the caruncle conforms closely to the wavelengths predicted by applying Bragg's Law of constructive reflection to measurements of the size and spatial organization of the collagen arrays. These observations constitute a novel mechanism of structural color production in animals. These collagen arrays are convergently similar to the smaller, highly structured collagen arrays in the mammalian cornea, which exploit the same physical mechanism to produce optical transparency. © 1994 Wiley‐Liss, Inc.
Localization and distribution of gap junctions in normal and cardiomyopathic hamster heart
Authors: Luque Eileen A. , Veenstra Richard D. , Beyer Eric C. , Lemanski Larry F.
Published: February 2005

Gap junctions in mammalian heart function to provide low‐resistance channels between adjacent cells for passage of ions and small molecules. It is clear that the almost unrestricted passage of ions between cells, ionic coupling, is required for coordinate and synchronous contraction. This knowledge of gap junction function has made it important to study their properties in normal and abnormal tissues. In the present study, we analyzed gap junction distribution in normal and cardiomyopathic heart tissue utilizing immunofluorescent and electron microscopy techniques. Frozen, unfixed sections of age‐matched normal and cardiomyopathic cardiac tissues were immunofiuorescently stained using an antibody directed against a specific peptide sequence of the connexin‐43 gap junction protein. These studies revealed a characteristic punctate staining pattern for the intercalated discs in normal tissues. Some of the intercalated discs in cardiomyopathic hearts appeared to stain normally; however, others stained diffusely. The pixel intensity distribution of the confocal images demonstrated a marked difference of up to 90% increase in the number of pixels in cardiomyopathic myocardium (CM), yet the pixel intensity of gap junctions had a decrease of approximately 60%. This suggests the possibility that connexin‐43 is present in CM cells in significant quantity; however, it does not become localized on the membranes as in normal cells. Electron‐microscopic findings corroborate these observations on CM cells by showing an irregular distribution of intercalated discs relatively smaller in size with abnormal orientation and distribution. © 1994 Wiley‐Liss, Inc.
Ultrastructure of phagocytic cells in the spleen of Psammophis sibilans (serpentes: Colubridae)
Authors: Saad Abdel Hakim
Published: February 2005

The spleen of Psammophis sibilans is composed mainly of red pulp, the white pulp being poorly developed. The white pulp lymphoid clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp consists of reticular cells intermingled with blood cells, sinusoids, and melanomacrophage centers (MMCs). Filtering of particulate matter from the blood occurs in the red pulp by phagocytes of the pulp cord. MMCs are formed by the association of free macrophages that have phagocytosed some blood cells. Early filtering of particulate matter by the phagocytes of the pulp cords may allow for more efficient phagocytosis of erythrocytes by the MMCs. © 1994 Wiley‐Liss, Inc.
Negative growth control of mitotically active imaginal cells (histoblasts) of the abdominal epidermis during metamorphosis of the housefly
Authors: Madhavan Kornath , Madhavan Mekkara Mandakavally
Published: February 2005

On the ventral side of each pupal abdominal segment of the housefly, there is a pair of histoblast nests, each containing about 600 diploid cells. These cells, during adult development, divide, replace intervening polytene larval epidermal cells (LEC), and form both the median sternite and the surrounding pleura of the adult segment. Since the histoblast nests and the LEC form a contiguous layer, we examined the role of these two types of cells in regulating the mitotic potential of the histoblasts during development of the median sternite. Two experimental approaches were used: deletion of one of the nests by thermocautery; and by disturbance of the continuity of the monolayered epidermis by thermocautery of, or topical application of heptanol on, the midventral LEC. Ablation of one of the contralateral nests resulted in a mirror image duplication of the hemisternite and pleura by the surviving nest. Disturbance of the continuity of the LEC produced mirror image duplication of the hemisternal pattern by each of the contralateral nests. From these results, we propose that the contralateral ventral nests mutually downregulate their mitotic potential by secreting regulatory factor(s) to produce the normal median sternite pattern and surrounding pleura. We also suggest that these chemicals act in a paracrine fashion, possibly through gap junctions in the LEC. © 1994 Wiley‐Liss, Inc.
Microanatomical organization of hepatic stroma of the brown trout, Salmo trutta fario (Teleostei, Salmonidae): A qualitative and quantitative approach
Authors: Rocha Eduardo , Monteiro Rogério A. F. , Pereira Carlos A.
Published: February 2005

Despite the absence of lobulation, light microscopy of serial sections of the liver of brown trout, Salmo trutta fario, reveals that the stromal elements are spatially organized as venous–biliary–arteriolar tracts (VBAT), venous–arteriolar tracts (VAT), biliary–arteriolar tracts (BAT), venous–biliary tracts (VBT), biliary tracts (BT), arteriolar tracts (AT), and isolated veins. These components are not two‐ but three‐dimensional entities, and the anatomical interrelationships among all entities are displayed. The VBAT, VAT, and VBT are considered portal tracts; the adjacent parenchymal zones are viewed as periportal areas. The veins emerging from those tracts are regarded as afferent, and related with periportal zones. The veins that do not communicate with the VBAT, VAT, or VBT are viewed as efferent. Only serial sectioning allows a definite recognition of afferent from efferent isolated veins. The morphometric study discloses that isolated veins occupy around 60% of the stromal areas. Nevertheless, the VBAT, VAT, and BT are also considerably important, occupying variable proportions of the stromal areas (8–12%). The VBT and BAT are less important in quantitative terms. No sexual diffences appear in either qualitative or quantitative terms. There is no structural support for an eventual macroorganization of hepatic tissues. It is suggested that the quantitative data can be useful, as standards for the normal hepatic architecture of brown trout. The paper emphasizes the importance of a general structural model for the fish liver and of the use of an internationally acceptable nomenclature. © 1995 Wiley‐Liss, Inc.
Annual changes in fine structure of inner epithelial lining of the ovary of a marine sculpin, Alcichthys alcicornis (Teleostei: Scorpaeniformes), with internal gametic association
Authors: Koya Yasunori , Takano Kazunori , Takahashi Hiroya
Published: February 2005

Alcichthys alciocornis has a viscous ovarian fluid in the ovarian cavity, which plays an important role in its unique mode of reproduction called internal gametic association (i.e., internal insemination and sperm‐egg association but a delay in the physiological fertilization until spawning). Seasonal changes in fine structure of the inner epithelial lining and capillary endothelium of the ovary revealed that ovarian fluid originated as a result of the secretory activity of the tissues. The ovarian cavity of A. alcicornis is lined with an ovigerous lamella epithelium and an ovarian wall epithelium. During the spawning period, both epithelia actively secreted proteinaceous substances which seemed to constitute the ovarian fluid. The substances appear to be synthesized in the rough‐surfaced endoplasmic reticulum from the material which was transported from the blood capillary, taken into the epithelial cells by endocytosis, accumulated in secretory vesicles via Golgi apparatus in the cells, and finally released into the ovarian cavity by exocytosis. Microapocrine secretion was also observed to occur in both epithelia. Secretory activity of both epithelia by exocytosis and microapocrine secretion showed distinct seasonal changes. Active exocytosis and microapocrine secretion were observed during the spawning period (April–May). These activities slightly declined during the degeneration period (May–June) and were lost during the early recovery period (July). During the mid to late recovery period (October–March), there was some exocytosis but no microapocrine secretion. © 1995 Wiley‐Liss, Inc.
Morphology of the abdominal wall in the bat, Pteronotus parnellii (Microchiroptera: Mormoopidae): Implications for biosonar vocalization
Authors: Lancaster Winston C. , Henson O. W.
Published: February 2005

We investigated the structure of the abdominal wall of Pteronotus parnellii and made comparisons with eight other species of Microchiroptera and one megachiropteran. Similar to other mammals, the abdominal wall of bats consists of the three flank muscles laterally and the m. rectus abdominis ventrally. In Microchiroptera, flank muscles are mostly confined to dorsal portions of the wall. The mm. transversus abdominis and obdominis and obliquus internus abdominis form the bulk of the wall; the m. obliquus externus is poorly developed. Ventrolaterally, a large portion of the wall is a dense, bilaminar aponeurosis, composed of collagen, elastin, and fibroblasts. The thicker, superficial lamina derives from the mm. obliquus internus and transversus abdominis. The deep lamina is a continuation of the transversalis fascia. Collagen fibers of the two fused laminae are oriented orthogonally, resulting in a resilient, composite fabric. Fascicles of the flank muscles are oriented along the margins of the aponeurosis so that their forces appear to be concentrated onto the aponeurosis. We suggest that this system is adapted for the regulation and generation of intra‐abdominal pressure. The abdominal wall of Pteropus, the one megachiropteran examined, lacks the derived aponeurosis and is similar to other mammals. We consider the abdominal wall of Microchiroptera to be analogous to the diaphragma, in that it functions in the regulation of pressure within body cavities and facilitates biosonar vocalization. © 1995 Wiley‐Liss, Inc.
Cytological and morphological ontogenesis and involution of the thymus in cichlid fishes (Cichlidae, Teleostei)
Authors: Fishelson Lev
Published: February 2005

The ontogenesis and involution of thymus in cichlid fishes was studied with the aim of comparing development in the bottom‐spawning species Tilapia zillii and T. tholloni, and in the mouth‐brooding species Oreochromis auratus, O. niloticus, O. mossambicus, and Sarotherodon galilaeus. For comparison, data are also given on bottom‐spawning Cichlasoma spp. from America and mouth‐brooding Pseudotropheus auratus and Aulonocara nyassae from Africa. Developmental changes were followed histologically by means of light and electron microscopy of sections, beginning with embryos 24 h after fertilization, up to 14‐year‐old specimens of O. auratus. In all these fish, the anlagen of the thymus glands begins from the third and fourth gill pouches, and their development shows a high correlation with the pace of general organogenesis, which differs greatly in the bottom‐spawning and mouth‐brooding cichlids. In juveniles of bottom‐spawners of 20–40 mm total length and in mouth‐brooders of 40–60 mm total length, three cell types are present in the thymus: thymocytes, with large, dense nuclei; epitheliocytes, with long cell extensions containing bundles of tonofibrils; and reticulocytes, with short, granulated cell extensions. Hassall's corpuscles start to develop in larvae of T. zillii at 20–35 mm total length, and in specimens of 40 mm and more total length the corpuscles are typical, formed by inner and outer rings of epitheliocytes. At 30–45 mm total length, cell debris starts to accumulate in the interior of the corpuscles as an early sign of regression. As involution continues, macrophages accummulate within and around the Hassall's corpuscles. The epitheliocyte rings are eventually completely broken down. Isles of thymocytes persist in tilapias from the age of 1–14 years, but most of the thymus volume is occupied by blood lacunae and pigmented macrophage aggregations. The morphology is similar in the mouth‐brooding species Pseudotropheus beginning at 1.5 years of age. © 1995 Wiley‐Liss, Inc.
Cellular ultrastructure and catecholamine histofluorescence of the heart of the Australian lungfish, Neoceratodus forsteri
Authors: Chopin L. K. , Bennett M. B.
Published: February 2005

Ultrastructural descriptions of the dipnoan heart are lacking. Many ultrastructural features of the heart of the Australian lungfish, Neoceratodus forsteri, resemble those of other lower vertebrates. The epicardial cells appear to be adapated for the exchange of material with the pericardial fluid. The most prominent features of the endocardial cells are numerous moderately electron‐dense vesicles found within the cytoplasm. These organelles might have an endocrine function. The myocardiocytes are typically small. The banding pattern of the sarcomere is shared with most fish. The intercalated disc has a convoluted path and consists of desmosomes and fascia adherens. Caveolae are a prominent feature of the sarcoplasm. The sarcoplasmic reticulum is sparse, and T‐tubules are lacking. Atrial myocardial dense bodies occur in vast numbers throughout the atrium and are occasionally seen in the ventricle. These vesicles are chromaffin‐positive but fail to show catecholamine fluorescence. They are likely to contain peptides related to ANP. Subendothelial cells exhibiting catecholamine‐specific fluorescence are scattered throughout the atrium. Ultrastructurally these cells contain many chromaffin‐positive granules. Chromaffin cells represent another cell type with a probable endocrine function within the heart of N. forsteri. © 1995 Wiley‐Liss, Inc.
Ultrastructure of the ventral sucker of Schistosoma mansoni cercaria
Authors: Cousin Carolyn , Dorsey Charles , Kennedy Veda , Ofori Kwame
Published: February 2005

The ventral sucker of Schistosoma mansoni cercaria is a cupshaped structure that is attached to the ventral surface of the organism by a homogeneous connective tissue that surrounds the acetabular glands. The sucker consists of an extensive complex of circular and longitudinal muscles. The longitudinal muscles extend outwoard in a radial pattern to form the cup of the organ. Intermingled with the muscles are nerve bundles and subtegumental cells (cytons). Dendritic nerve fibers connect to sensory papillae which are found on the surface tegument. Two types of sensory papillae are present: a commonly found unsheathed uniciliated papilla, and a previously unidentified tegumental encapsulated structure. Tegument with spines covers the ventral sucker, although the tegumental encapsulated sensory papilla lacks spines. © 1995 Wiley‐Liss, Inc.
Relationship of the tubular system with other organelles in chlorride cells of the channel catfish, Ictalurus punctatus
Authors: Henderson Vernon
Published: February 2005

The morphology of chloride cells in the channel catfish, Ictalurus punctatus, has been studied by transmission electron microscopy. The chloride cell possesses abundant tubules, mitochondria, and granules. The employment of a special membrane stain in conjunction with a two‐ or tridimensional analysis reveals a complex interjoining and interlocking ring system of tubules. Tubular sides constituting the complex rings frequently lack granules. The tubular rings join with tubulous mitochondrial profiles and other cytoplasmic components. © 1995 Wiley‐Liss, Inc.
Structure of the glomerular capillaries of the domestic chicken and desert quail
Authors: Casotti Giovanni , Braun Eldon J.
Published: February 2005

The glomerular capillary architecture of nephrons that include a loop of Henle (looped) and those that lack the loop (loopless) nephrons was examined qualitatively and quantitatively by electron microscopy in Gallus gallus and Callipepla gambelii. The glomerular capillaries of looped nephrons form a dichotomously branched network, while those of loopless nephrons are arranged loosely, and the majority are unbranched. There was no significant difference in the diameter of the glomerular capillaries between looped and loopless nephrons; however, in all cases the diameter of the afferent arteriole was significantly larger than that of the efferent arteriole. Based on size alone, the predicted blood flow rate in the efferent arteriole in 20% that of the afferent arteriole in G. gallus and 7% that of the afferent arteriole in C. gambelii. There was no significant difference in the volume density (Vv) of the glomerular capillaries between looped and loopless nephrons. However, the surface area density (Sv) of the glomerular capillaries in loopless nephrons of C. gambelii was significantly larger than for the looped nephrons, and for the loopless nephrons in G. gallus. This suggests that there may be a decrease in blood flow rate along the glomerular capillaries of the loopless nephrons in C. gambelii. Overall, the results indicate that the avian glomerular capillaries are less complex than those of mammals. Reasons may be that either avian blood is more viscous than that of mammals or that avian erythrocytes may be unable to fit physically through a tight intertwining network of capillaries due to the presence of a nucleus, which limits the tank‐treading ability of avian erythrocytes. © 1995 Wiley‐Liss, Inc.
Biomechanical adaptation of ulnar cross‐sectional morphology in brachiating primates
Authors: Hallgrimsson Benedikt , Swartz Sharon
Published: February 2005

The forelimbs of hylobatids (gibbons and siamang) are distinctive among tetrapods in that they are loaded in overall tension during normal locomotion. While hylobatid ulnae must also encounter bending stresses in the course of their full range of locomotor behavior, their loading regime differs from that of quadrupedal anthropoids in that these bending stresses are distributed evenly along the bone, are not exerted in a preferred plane, and are probably of generally lower magnitude. This study examines the degree to which hylobatid ulnae are adapted to this suspensory loading regime. We obtained cross‐sections of ulnae at various increments along the length of the bone using CAT scans. The sample comprises 476 cross‐sections representing the ulnae of 25 individuals from five species of comparable body size. We show that in gibbons and siamang, the patterning of ulnar cross‐sectional area and resistance to bending in the dorsoventral plane along the ulnar diaphysis differ from that of similarly sized quadrupedal anthropoids in the manner predicted by a suspensory loading regime. We also find the same pattern for the ulnae of Ateles, whose loading regime may be fairly similar to that of hylobatids. However, we find that the cross‐sectional shape of the ulnar diaphysis in hylobatids and Ateles does not differ from that of quadrupedal monkeys in the manner predicted by a suspensory loading regime. © 1995 Wiley‐Liss, Inc.
Fiber‐type compositions in postnatal chicken muscle spindles with low intrafusal fiber counts and their developmental significance
Authors: Maier Alfred
Published: February 2005

The fiber‐type composition of postnatal chicken leg muscle spindles with from one to four intrafusal fibers was examined in sections incubated with monoclonal antibodies against fast and slow myosin heavy chains. In monofibral spindles the lone intrafusal fiber was almost always fast. In duofibral spindles usually one slow and one fast fiber were present. Trifibral spindles most often displayed two fast and one slow fiber, whereas quadrofibral receptors characteristically contained two slow and two fast fibers. Earlier results showed that the primary intrafusal myotube in nascent spindles has almost always a fast myosin heavy chain profile and that the proportion of slow myotubes and fibers increases as intrafusal fiber bundles grow in size. Data from postnatal chicken leg muscles collected here suggest that up to the first four fibers this proportional increase can be largely accounted for if consecutive intrafusal fibers arise in a fast‐slow‐fast‐slow sequence. The late recognition during myogenesis of primary intrafusal myotubes and their fast myosin heavy chain profiles warrant exploring if nascent chicken muscles spindles are first seeded by fast fetal myoblasts. © 1995 Wiley‐Liss, Inc.
Postembryonic development of the ovary in the penicillate diplopod, Eudigraphis nigricans (Miyosi) (Diplopoda, Penicillata)
Authors: Yahata Kensuka , Makioka Toshiki
Published: February 2005

Postembryonic development of the ovary through the larval stages was studied in a penicillate diplopod, Eudigraphis nigricans. In the first instar larva a single young cell cluster, consisting of about 20 spherical gonial cells and some smaller interstitial cells, exists beneath the alimentary canal in the third body segment. The gonadal epithelium encompasses the upper surface of this young cell cluster by the end of the first instar. The epithelium then extends forward and backward to form a single long sac‐like gonad, leaving the young cell cluster on the center of the gonadal floor as a mound‐shaped germarium. In an early second‐instar larva, very early previtellogenic oocytes accompanied by some interstitial cells appear in the front and rear surfaces of the ovarian germarium. During the period from the third through the seventh (the last) larval instar, some cell clusters containing several previtellogenic oocytes and interstitial cells successively separate forward and backward from the germarium to form a series of paired patch‐shaped vitellarial areas on the extending ventral ovarian epithelium. In each vitellarial area, some of the interstitial cells surround the oocytes to form the follicles. In the seventh instar, the ovarian lumen is extremely expanded, and the late previtellogenic oocytes in the vitellarial areas encroach upward into the ovarian lumen. These oocytes floating in the ovarian lumen are still connected with their own vitellarial areas by partial extensions of their follicles.

Some phylogenetic implications of the basic characteristics in structure and postembryonic development of the ovary are discussed. © 1995 Wiley‐Liss, Inc.
Cyton II: A subtegumental cell type in the cercaria of Schistosoma mansoni
Authors: Dorsey Charles , Cousin Carolyn
Published: February 2005

In Schistosoma mansoni cercaria, an aggregate of subtegumental cells is found in a small, dorsoanterior area of the body (middivision). These cells are nestled between two laterally positioned flame cells and the muscle that delimits the anterior end of the body, and the anterior end of the central ganglion. This highly amorphous cell type, designated as cyton II, has a heterochromatic nucleus and a cytoplasm that is elaborated into coarse, tortuous processes. Its cytoplasm contains ribosomes, mitochondria, sparse amounts of endoplasmic reticulum, and two types of circular‐to‐oval concentric membranous bodies. One type has an electron‐dense core and measures 200–250 nm on the short axis, and the other is completely membranous and measures 100–125 nm on the short axis. The cell body of cyton II communicates with the tegument that covers a small, dorsoposterior area of the anterior organ (oral sucker); however, we could not confirm a tegumental connection with the body division. When cercariae transform into schistosomules, the concentric membranous bodies of cyton II migrate into the anterior organ's tegument via cytoplasmic processes of the cell. The major function of previously described cells that have similar membranous bodies is to supply additional membranes to the outer tegument during development into an adult worm. A multilaminated outer membrane is an adaptation to the survival of the schistosomule and adult worm in the bloodstream of the vertebrate host (Hockley amd McLaren [′73]). The presence of membranous bodies from cyton II in the tegument does not confirm that this cell type participates in the formation of multilaminated membranes. Its precise function remains to be determined. © 1995 Wiley‐Liss, Inc.
Cranial features of dendrobatid larvae (Amphibia: Anura: Dendrobatidae)
Authors: Haas Alexander
Published: February 2005

The larval neurocranium and visceral arches of seven dendrobatid species representing four genera are described, based on cleared‐and‐stained and serially sectioned specimens. A variety of characters is shared by all seven species. Larval features do not substantiate the assumption of close ranoid affinities of the Dendrobatidae. Instead dendrobatid larvae share features such as the special quadripartite cartilago suprarostralis, the lack of the larval processus oticus, the presence of three foramina acustica, and the lack of a foramen perilymphaticum accessorius with many bufonoid larvae. The first of these characters is unique to bufonids, hylids, dendrobatids, and some New World leptodactylids; the other characters also occur in pelobatids and are presumably plesiomorphic for the Neobatrachia. The free proximal ends of Ceratobranchialia II and III are an autapomorphy of the Dendrobatidae supporting the monophyly of the family. Some features of the cranium are paedomorphic: low cartilago orbitalis, lack of connection between cartilage orbitalis and otic capsule (most species), and vestigal taeniae tecti. New anatomical terms are introduced. © 1995 Wiley‐Liss, Inc.
Sperm storage in the oviduct of the tropical rock lizard, Psammophilus dorsalis
Authors: Srinivas S. R. , Hegde S. N. , Sarkar H. B. D. , Shivanandappa T.
Published: February 2005

The female rock lizard, Psammophilus dorsalis (Agamidae), lays multiple clutches of eggs over a period of 6 months (June–December). The later clutches of eggs are presumably fertilized by sperm stored from earlier matings, since testes and epididymides are regressed after August. Sperm storage is seen in pockets of the anterior vaginal region of the oviduct. Sperm recovered from the uterovaginal region are intact and motile. Discrete granules resembling the secretory granules present in the vas deferens also occur along with sperm in the vaginal sperm storage structures. The PAS‐positive granules and acid phosphatase form important components of the secretions present along with sperm in the vaginal sperm storage pockets. The epithelium of the vaginal sperm storage pockets is PAS‐positive and contains lipid. Several enzymes, including hydroxysteroid dehydrogenases and hydrolases, are localized histochemically in the epithelium of the vaginal sperm storage pockets. A possible role is suggested for the secretions from the male reproductive tract during sperm storage in the oviduct, in which physiological “dormancy” of the sperm during their storage may be maintained by the metabolic “milieu” in the vaginal sperm storage pockets by a mechanism similar to that effecting dormancy of the epididymal sperm in the male. © 1995 Wiley‐Liss, Inc.
Convergent evolution of the vestibular organ in the subterranean mole‐rats, Cryptomys and Spalax, as compared with the aboveground rat, Rattus
Authors: Lindenlaub Thies , Burda Hynek , Nevo Eviatar
Published: February 2005

The membranous labyrinth of the vestibular organ (examined in toto) in two unrelated species of subterranean rodents, Cryptomys sp. from Zambia and Spalax ehrenbergi from Israel, was in many parameters (streamline length, curvature radius, and cross‐sectional area of the lumen) relatively or even absolutely (especially the cross‐sectional area) larger than in the laboratory Norway rat. The mechanical sensitivity of the vestibular organ (estimated according to the mathematical model of Oman et al., [1987] Acta. Otolaryngol (Stockh.) 103:1–13) was similar in both subterranean rodent species and significantly higher than that in the laboratory rat. The most pronounced differences in morphometry and the resulting mechanical sensitivity between the subterranean forms and the rat occurred in the lateral (i.e., phylogenetically and ontogenetically most recent and presumably most plastic) semicircular duct. The area of the sensory epithelia, and density and total numbers of vestibular receptors, were estimated on surface specimens for both maculae and for all three cristae for all three species. While the density of hair cells in comparable sensory epithelia was similar in all three species, the sensory area and thus, also, the total receptor counts were significantly larger in both subterranean forms. The peripheral vestibular organ in subterranean rodents is, in comparison to a generalized aboveground dwelling form, i.e., the rat, progressively specialized, and in any case cannot be denoted as degenerate. © 1995 Wiley‐Liss, Inc.
Lectin histochemical identification of carbohydrate moieties in opossum chemosensory systems during development, with special emphasis on VVA‐identified subdivisions in the accessory olfactory bulb
Authors: Shapiro Lena Shnayder , Halpern Mimi , Ee Pei‐Lee
Published: February 2005

Lectins, sugar‐binding molecules of nonimmune origin, were used in this study to describe the development of the main olfactory and vomeronasal systems in the Brazilian gray short‐tailed opossum, Monodelphis domestica. A battery of seven lectins of the N‐acetylgalactosamine/galactosebinding group was used. Of the seven lectins, only two, Vicia villosa agglutinin (VVA) and Griffonia (Bandeiraea) simplicifolia lectin I‐isolectin B4 (GS I‐B4), were specific to the vomeronasal system. The other five lectins recognized carbohydrates in both chemosensory systems, although the binding was more intense in the accessory olfactory system. Furthermore, whereas six of the lectins stained the adult opossum accessory olfactory bulb (AOB) homogeneously, the VVA lectin distinguished two regions of the AOB. Similar to the expression of olfactory marker protein (OMP) (Shnayder et al. [1993] Neuroreport 5:193–196), the rostral half of the AOB stained much darker with VVA than the caudal half, and the onset of the restricted pattern of staining at age 45 days also coincided. We conclude that (1) GS I‐B4 and VVA recognize cell surface carbohydrate moieties specific to the vomeronasal, but not to the main olfactory, system, and (2) the carbohydrate moiety that is recognized by the VVA lectin, presumably terminal N‐acetyl‐galactosamine, is both temporally and spatially restricted in the opossum AOB. These results are discussed in the framework of other known spatially restricted molecules of the two major nasal chemosensory systems. © 1995 Wiley‐Liss, Inc.
Structure of the extraembryonic matrices around the benthic embryos of Patiriella exigua (Asteroidea) and their roles in benthic development: Comparison with the planktonic embryos of Patiriella regularis
Authors: Cerra Anna , Byrne Maria
Published: February 2005

The extracellular matrices (ECMs) surrounding the benthic embryos and larvae of the seastar Patiriella exigua and the planktonic embryos of Patiriella regularis were examined by transmission and scanning electron microscopy. Three ECMs surround unhatched embryos: An outer jelly coat, a fertilization envelope, and an inner hyaline layer. The ECMs of P. exigua are modified for supporting benthic development. The dense jelly coat attaches the embryo to the substratum, and the fertilization envelope forms a though protective case. In comparison, P. regularis has a less dense jelly coat and a thinner fertilization envelope. The hyaline layer of both species is comprised of three main regions: An intervillous layer overlying the epithelium, a supporting layer, and a coarse meshwork layer. Unhatched P. exigua have an additional outer amorphous layer that adheres to the fertilization envelope. As a result, the hyaline layer forms a continuous ECM that unites the embryonic surface with the fertilization envelope. Embryos of P. exigua removed from their fertilization envelopes lack the outer amorphous region, have a poorly developed hyaline layer, and do not develop beyond gastrulation. It appears that the substantial hyaline layer of P. exigua and its attachment to the fertilization envelope are essential for early development and that this ECM may function as a gelatinous cushioning layer around the benthic embryos. At hatching, the amorphous layer is discarded with the envelope. In contrast, an amorphous layer is absent from the hyaline layer of P. regularis. The demembranated embryos of this species have an ECM similar to that of controls and develop normally to the larval stage. © 1995 Wiley‐Liss, Inc.
Scanning electron microscopic study of intestinal mucosa of the Nile crocodile (Crocodylus niloticus)
Authors: Kotzé Sanet H. , Soley John T.
Published: February 2005

As part of an ongoing study of the intestinal tract of the Nile crocodile Crocodylus niloticus, the appearance of the small intestinal mucosa was examined using a scanning electron microscope (SEM). The duodenum displayed ridge‐like and complex primary folds, both of which were arranged in a longitudinally directed zigzag pattern. The two types of folds alternated with each other, with the second type following the zigzag contours of the first. The folds were covered with polygonal‐ and dome‐shaped epithelial cells. The latter cell type was less common and was restricted in location to the proximal two thirds of the mucosal folds. Both types of epithelial cells were covered with stubby microvilli which displayed a distinct linear arrangement. Goblet cells were present between the absorptive cells. In the jejunum the basic pattern of the folds persisted except that both types of primary folds became tall and leaf‐like. The angle of the zigzag pattern was less acute than in the duodenum. In the ileum the two types of alternating folds decreased in height and were arranged in a longitudinally directed wave‐like fashion. The zigzag mucosal folds of the small intestine ended abruptly at the ileorectal junction. The rectum displayed low, irregular folds which formed occasional large, puckered, rosette‐shaped structures. The particular arrangement of the intestinal folds fulfills the dual function of promoting the absorptive process and facilitating the smooth passage of the intestinal contents. © 1995 Wiley‐Liss, Inc.
A commentary on the segmental motor system of the turtle: Implications for the study of its cellular mechanisms and interactions
Authors: Callister Robert J. , Laidlaw Douglass H. , Stuart Douglas G.
Published: February 2005

A commentary is provided on the segmental motor system of the turtle Pseudemys (Trachemys) scripta elegans with an emphasis on neuronal, neuromuscular, and muscular mechanisms that control the development of force under normal, fatiguing, and pathophysiological conditions. For the central neuronal component of the segmental motor system, it has recently been shown that intracellular analysis of the firing properties of motoneurons and interneurons can be undertaken for relatively long periods of time in in vitro slices of the lumbosacral spinal cord of the adult turtle. In other less reduced in vitro preparations, analyses are available on complex motor behaviors generated by the isolated spinal cord. These behaviors of spinal neuronal networks are analogous in key aspects to those generated by the isolated in vivo cord, and by the cord in intact preparations. These results suggest that the neuronal components of the segmental motor system can now be studied from the cellular/molecular level of analysis in in vitro slice preparations to the systems level in conscious, freely moving animals. The in vitro approach can also be used for the analysis of cellular mechanisms in suprasegmental brain structures, which contribute to the control of voluntary movement. For the peripheral neuromuscular component of the segmental motor system, information is now available on muscle fiber types and selected aspects of sensory innervation, and it is feasible to study the mechanical and biochemical properties of motor units. As such, the turtle presents a valuable model for exploring interrelations between the neuronal and mechanical components of the segmental motor system of the generalized tetrapod. A prominent feature of these recent developments is the extent to which they have been deriven by findings that have emphasized an evolutionary conservation of motor‐control mechanisms extending from ion channels, at the cellular level, to the control of multijointed movements at the systems level of analysis. © 1995 Wiley‐Liss, Inc.
Isolated cell type corpora allata in adults of the loreyi leafworm, Leucania loreyi duponchel (Lepidoptera: Noctuidae)
Authors: Kou R. , Tu M. P. , Chang C. Y. , Yin C.‐M.
Published: February 2005

The corpora allata in adult Loreyi leafworms Leucania loreyi (Lepidoptera: Noctuidae) exhibit sexual dimorphism. The male possesses right and left corpora allata of about the same size. Each gland is composed of a cluster of approximately 40 semi‐transparent, spherical, isolated cells held together by fine tracheae and nerve fibers. The largest cell diameter found in male glands was 203 pm. In contrast, the female gland cells and clusters are much smaller. The largest dimensions of one whole female gland cluster were 452 μm in length and 280 μm in width. Using bilateral and unilateral larval allatectomy, we confirmed that the adult isolated cell type glands develop ontogenetically from larval capsular type glands. Ultrastructural study re‐ vealed many similarities between the subcellular structures of the isolated cell type glands of L. loreyi and the more common capsular gland reported by others. These similarities include very large numbers of mitochondria, abun‐ dant whorled smooth endoplasmic reticulum, irregularly shaped nuclei, Golgi bodies, and free ribosomes. Compared with the corpora allata of 3‐ to 9‐day‐old adults, the glands of 1‐day‐old adults possessed much less smooth endoplasmic reticulum. The gland cells in females usually have more neurosecretory nerve endings, less‐abundant stacked smooth endoplasmic reticulum, and less‐ defined interdigitations than the gland cells in males. © 1995 Wiley‐Liss, Inc.
Functional anatomy of the pigeon hand (Columba livia): A muscle stimulation study
Authors: Vazquez Rick J.
Published: February 2005

The morphology and function of all muscles controlling the pigeon hand were analyzed. Muscle action was determined in situ by inducing contraction via silver wire electrodes in anesthetized birds. EMG electrodes were implanted in the test muscle and an adjacent muscle to monitor contraction and volume conduction respectively. Results indicate that pigeons have fine control of hand and digit movements. However, the directions of movement are restricted. Movements have been eliminated or severely limited in those directions that experience strong stress during flight. Such restrictions may reduce the amount of muscular activity required for stabilization of the hand and its components. Mobility is retained in directions not subject to large stresses and where movement is essential for the kinematics of flight to be executed properly. © 1995 Wiley‐Liss, Inc.
Seasonal variation in ovarian histology of the viviparous lizard Sceloporus torquatus torquatus
Authors: Uribe María Del Carmen A. , Omana María Elodia Mendez , Quintero JoséE. Gonzalez , Guillette Louis J.
Published: February 2005

Changes in ovarian histology during the reproductive cycle of the viviparous lizard Sceloporus torquatus torquatus are described. In general, the variation in follicular histology observed during the seasonal cycle is similar to that of other lizards. Sceloporus t. torquatus exhibits a cycle in which small, previtellogenic follicles exist in the ovary from December to August. Vitellogenesis occurs between September and November, followed by ovulation from late November to early December. Parturition occurs the following spring. After ovulation, the remaining follicular cells form the corpus luteum and luteolysis did not occur until April‐May. Follicular atresia is commonly observed in previtellogenic follicles with polymorphic granulosa, but occurs less frequently in follicles during late vitellogenesis. There are two germinal beds in each ovary. The yolk nucleus is evident in young oocytes as is a vacuolated ooplasma prior to vitellogenesis. Extensive polymorphism is observed in yolk platelets. Mast cells and secretory cells are observed in the thecal layer of the follicular wall as are melanocytes in the ovarian stroma. © 1995 Wiley‐Liss, Inc.
Cytoplasmic bags: Containers for discarded paraflagellar membranes in spermiogenesis of graphosome lineatum (Pentatomidae, Hemiptera, Insecta)
Authors: Wolf Klaus Werner
Published: February 2005

The process of cytoplasmic sloughing is described in spermiogenesis of a stink bug, Graphosoma lineatum, using transmission electron microscopy of ultrathin sections. Tails of young spermatids possess a wide cytoplasmic layer lateral to the axoneme and the nenbenkern derivatives. Membranous sheets, comprised of cisternae of endoplasmic reticulum with very narrow lumina, are arranged parallel to these organelles. More advanced spermatids show only a thin cytoplasmic layer largely devoid of membranes. At this stage, large evaginations of the flagellar membrane, termed cytoplasmic bags, are found in association with the spermatid tails. The most prominent elements within these bags are concentric layers of endoplasmic reticulum of the type previously found in spermatid tails. This relationship suggests that the cells rid themselves of cytoplasmic membranes throughout spermiogenesis via inclusion into cytoplasmic bags. Upon release from the nucleate cytoplasm, the cytoplasmic bags become more and more electron‐dense and degenerate. © 1995 Wiley‐Liss, Inc.
Histological examination of flight muscle development and breakdown in Bemisia tabaci (Homoptera: Aleyrodidae): Relationship to age and flight behvior
Authors: Blackmer J. L. , Lindley V. A. , Byrne D. N.
Published: February 2005

Bemisia tabaci exhibited their longest flights between 3 and 5 days following adult eclosion. They rarely engaged in flight when they were < 4 hr old and were only capable of short‐duration flights after day 7. This difference in flight capacity appears to be associated with changes in the flight musculature and mitochondria. Myofibrils and mitochondria accounted for approximately 50% and 33% of the area within the flight muscles, respectively. These two elements, however, varied with the age and sex of the whitefly. The percentage of the total area occupied by myofibrils was lower in 9‐day‐old males relative to females and all other age categories. Sarcomere length decreased in older whiteflies, regardless of the sex. Myofibril diameter did not vary with the age of the whitefly, but the diameter of female whitefly myofibrils was greater than the diameter of male whitefly myofibrils. The number of myosin filaments within a myofibril unit increased with age, peaking at 5 days of age for females and 7 days of age for males. In all age groups, females had more myosin filaments than were found in males.

Changes in mitochondria and levels of glycogen were related to the observed differences in flight activity. The area occupied by mitochondria was small in < 4‐h‐old and 9‐day‐old whiteflies, and mitochondrial cristae were undeveloped in newly emerged whiteflies. In 7‐ and 9‐day‐old whiteflies the cristae began to separate, leaving visible spaces within the mitochondria. Glycogen granules were abundant in the flight musculature of newly emerged (< 4‐hr‐old), 1‐day‐old and 3‐day‐old whiteflies, but by 5 days of age only 25% of whiteflies contained glycogen granules. Seven‐ and 9‐day‐old whiteflies contained no visible glycogen.

An examination of the flight muscle of whiteflies after flights of varying duration (up to 60 min) revealed no relationships between flight duration and the number of mitochondria or the percentage of the total area occupied by mitochondria. There was, however, a positive relationship between flight duration and the percentage of total area occupied by myofibrils. © 1995 Wiley‐Liss, Inc.