bluuebunny/crossref_metadata_2025_split huggingface dataset:
Salivary glands of the cockroach, Periplaneta americana: New data from light and electron microscopy
Authors: Just F. , Walz B. 
Published: February 2005

AbstractWe have reinvestigated the morphology of the salivary glands in the cockroach, Periplaneta americana, by light, electron, and confocal laser scanning microscopy. All secretory acini have a uniform structural layout. They consist of three cell types: peripheral cells, central cells, and duct cells. One pair of peripheral cells forms the base of each acinus. The central cells, arranged concentrically in a fourfold symmetry around the most proximal part of the acinar ducts, lie next downstream. In every acinus, duct cells accompany the central cells and form a thin sheet on the apical surface of the latter. This apical lining of the duct cells is regularly fenestrated, and the central cells secrete the contents of their secretory vesicles only through these openings into the lumen of the ducts. Peripheral cells and central cells are never in direct physical contact, because, apically, extensions of the inner acinar duct cells intervene between the cells. Basally, thin extensions of the basement membrane separate the cell types. We have found no morphological evidence for the existence of electrical coupling (gap junctions) between the saliva‐producing cells. Our ultrastructural data support the view that the peripheral cells are responsible for water and electrolyte transport, whereas only central cells secrete the proteinaceous components of the saliva.We have found that the duct cells distal to the acini are also specialized for ion and water transport. They have a prominent basal labyrinth containing numerous mitochondria and a highly folded apical surface. The folded apical membrane surface is coated with electron‐dense particles on its cytoplasmic side; these particles are probably portasomes. Our investigation provides morphological evidence that the duct cells distal to the secreting acini are able to modify primary saliva. © 1994 Wiley‐Liss, Inc.
Follicular placenta of the viviparous fish, Heterandria formosa: II. Ultrastructure and development of the follicular epithelium
Authors: Grove Bryon D. , Wourms John P. 
Published: February 2005

AbstractEmbryos of the viviparous poeciliid fish, Heterandria formosa, develop to term in the ovarian follicle where they undergo a 3,900% increase in embryonic dry weight. Maternal‐embryonic nutrient transfer occurs across a follicular placenta that is formed by close apposition of the embryonic surface (i.e., the entire body surface during early gestation and the pericardial amnionserosa during mid‐late gestation) to the follicular epithelium. To complement our recent study of the embryonic component of the follicular placenta, we now describe the development and fine structure of the maternal component of the follicular placenta. Transmission electron microscopy reveals that the ultrastructure of the egg envelope and the follicular epithelium that invests vitellogenic oocytes is typical of that described for teleosts. The egg envelope is a dense matrix, penetrated by microvilli of the oocyte. The follicular epithelium consists of a single layer of cuboidal cells that lack apical microvilli, basal surface specializations, and junctional complexes. Follicle cells investing the youngest embryonic stage examined (Tavolga's and Rugh's stage 5–7 for Xiphophorus maculatus) also lack apical microvilli and basal specializations, but possess junctional complexes. In contrast, follicle cells that invest embryos at stage 10 and later display ultrastructural features characteristic of transporting epithelial cells. Apical microvilli and surface invaginations are present. The basal surface is extensively folded. Apical and basal coated pits are present. The cytoplasm contains a rough endoplasmic reticulum, Golgi complexes, and dense staining vesicles that appear to be lysosomes. The presence of numerous apically located electron‐lucent vesicles that appear to be derived from the apical surface further suggests that these follicle cells may absorb and process follicular fluid. The egg envelope, which remains intact throughout gestation and lacks perforations, becomes progressively thinner and less dense as gestation proceeds. We postulate that these ultrastructural features, which are not present in the follicles of the lecithotrophic poeciliid, Poecilia reticulata, are specializations for maternal‐embryonic nutrient transfer and that the egg envelope, follicular epithelium, and underlying capillary network form the maternal component of the follicular placenta. © 1994 Wiley‐Liss, Inc.
Pufferfish inflation: Functional morphology of postcranial structures in Diodon holocanthus (Tetraodontiformes)
Authors: Brainerd Elizabeth L. 
Published: February 2005

AbstractFor the purpose of defending itself against predators, the balloonfish (Diodon holocanthus) can triple its body volume by pumping water into its stomach. Diodon holocanthus exhibits striking structural and functional specializations for inflation. The stomach of the balloonfish is highly extensible and has lost its digestive function, it is repeatedly folded upon itself and is lined with transitional epithelium. The peritoneal cavity of the balloonfish is also large and extensible. During inflation, the stomach expands into an existing peritoneal space surrounding the axial musculature and presses the folded peritoneum out into potential peritoneal spaces ventral to the head and surrounding the dorsal fin, anal fin, and caudal peduncle; only the dorsal and lateral surfaces of the head are unaffected. Balloonfish skin is also specialized for inflation. Because the collagen fibers in the dermis of unstretched skin are wavy, little force is required to extend the skin up to 40% of its rest length. At high strains, the collagen fibers are stressed directly and the skin suddenly becomes stiff. Stiff skin surrounding a ball of incompressible water provides a rigid framework for the support of the erectile spines, and the balloonfish becomes a formidable, spiny sphere. However, not all of the structural and functional features that contribute to the ability of balloonfish to inflate are evolutionary adaptations specifically for inflation. Absence of pleural ribs, absence of a pelvis, and the orthogonal arrangement of dermal collagen sheets in the skin were all present in the ancestor of pufferfishes, and thus, must be considered exaptations. Sagittal plane flexibility of the vertebral column may be an epiphenomenon of the lengthening of the body cavity for more spherical inflation. Together these structural and functional features—whether adaptations, exaptations, or epiphenomena—combine to produce a highly effective mechanical defense. © 1994 Wiley‐Liss, Inc.
Ontogeny of the sea bass spleen (Dicentrarchus labrax): A light and electron microscopic study
Authors: Quesada J. , Villena M. I. , Navarro V. 
Published: February 2005

AbstractThe splenic rudiment in sea bass (Dicentrarchus labrax) appears 18 days after hatching in the right side of the body, close to the dorsal wall of the anterior part of the intestine. It acquires its final localization after about 2 months in a middle‐ventral position between the cecal part of the stomach and the first intestinal loop. The haemopoietic activity of this spleen during organogenesis varies with age. During the first 40 days only erythropoietic activity is shown, after which thrombopoiesis begins and the first lymphocytes appear. At the time that the amorphous extracellular matrix increases, some reticular, cells of the stroma undergo an active lipid synthesis, which ceases when the larvae are about 2 months old. All the above coincides with a decrease in erythropoiesis and total vascular development, although the ellipsoids and sinusoids do not present their final structure until later stages. These structural variations create microenvironmental conditions which favor modifications in the activity of the spleen. This relation between microenvironment and changes in haematopoietic organ function has also been described in mammals and birds (Metcalf and Moore [1971] Frontiers of Biology. Amsterdam: North Holland; Quesada et al. [1985] J. Submicrosc. Cytol. 17:537–540; Yassine et al. [1989] Cell Diff. Dev. 27:29–45). © 1994 Wiley‐Liss, Inc.
Microscopy of vascular architecture and arteriovenous communications in the spleen of two odontocetes
Authors: Tanaka Yasukazu 
Published: February 2005

AbstractThe red pulp of the spleens of the short‐finned pilot whale (Globicephala macrorhynchus) and the Pacific bottle‐nosed dolphin (Tursiops truncatus gilli) (Odontoceti) were examined by light and electron microscopy and found to comprise two venous layers, an inner and an outer. The inner layer is homologous to the intermediate zone (IZ) of primitive‐type mammalian spleens and contains sinusoids consisting of endothelial cells and a thin layer of extracellular deposits. Its vascular structure is unclear. The venous vessels of this layer eventually communicate with veins of the perivenous outer layer. The perivenous layer contains veins of various sizes, interstitial elements, and trabeculae. It is filled with blood cells, particularly plasma cells, but no myeloid cells. The perivenous layer (PVL) is homologous to the red pulp of common mammalian spleens but shows signs of involution.The white pulp gives origin to arterial terminals that end in the red pulp, where they communicate directly with the sinusoidal veins producing a closed circulation. The arterial terminals do not show ellipsoids. The presence of an IZ with a closed circulation and the involution of the red pulp makes the spleen of Odeontoceti another example of a mammalian spleen of the primitive type that has been altered by the evolutionary process. Vascular remodelling of the spleen of Odontoceti seems to follow the pattern noted in the spleens of nonmammalian vertebrates. © 1994 Wiley‐Liss, Inc.
Morphology and density distribution of cone photoreceptor in the retina of the atlantic stingray, Dasyatis sabina
Authors: Logiudice F. T. , Laird R. J. 
Published: February 2005

AbstractLight miscroscopy of the retina in the Atlantic stingray, Dasyatis sabina, reveal two distinct photoreceptor types. Histological criteria establish the two cell types as morphological rods and cones. The retina was studied through a sequential series of vertical sections in a protocol designed to evaluate the entire retina. By performing differential counts in multiple regions and expressing cones as a percent of the total photoreceptors in a domain, it was possible to determine relative cone density and distribution. Cone distribution varies throughout the retina in two patterns. First, relative cone density gradually decreases peripherally. Second, a cone‐rich band occurs along the horizontal axis of the eye, extending from ora serrata to ora serrata. This structure appears to be a visual streak. Both distribution patterns are statistically significant and are consistent among animals regardless of age. © 1994 Wiley‐Liss, Inc.
Immunohistochemical distribution of calbindin D‐28k and parvalbumin in the head of the caudate nucleus and substantia nigra of the cat
Authors: De Las Heras Silvano , Hontanilla Bernardo , Mengual Elisa , Giménez‐Amaya José Manuel 
Published: February 2005

AbstractThe heterogeneous anatomy of both the dorsal striatum at the level of the head of the caudate nucleus and of the substantia nigra of cats was analyzed immunohistochemically using two calcium‐binding proteins, namely, calbindin D‐28k and parvalbumin. The striatal histochemical markers nicotinamide‐adenine dinucleotide phosphate diaphorase and acetylcholinesterase were revealed in sections adjacent to those used for the immunohistochemical procedure. The distribution of both the calbindin D‐28k and the parvalbumin immunoreactivities is heterogeneous in dorsal, ventral, lateral, and medial areas of the head of the caudate nucleus and is in register with the striosome/matrix pattern displayed by the histochemical markers. These calcium‐binding proteins preferentially are located in the matrix compartment of the rostral caudate nucleus. Moreover, in some areas of the rostral two‐thirds of the substantia nigra, calbindin D‐28k and parvalbumin immunoreactivities appear to follow a complementary pattern that is quite different from the mesencephalic distribution of these two calcium‐binding proteins. © 1994 Wiley‐Liss, Inc.
Histoenzymological studies on embryonic and posthatching development of the ovary in the tropical oviparous lizard, Calotes versicolor
Authors: Doddamani Laxmi S. 
Published: February 2005

AbstractThe development of the ovary in the lizard Calotes versicolor has been studied histologically and histochemically from the day of oviposition (stage 27) to 2 months after hatching. The gonadal component appears as a genital ridge at stage 27. Sex differentiation of gonads occurs at stage 34, which indicates that the period of sexual bipotentiality is very brief. Oogenesis starts at stage 35, where preleptotene and leptotene oocytes appear for the first time in the ovary. The zygotene and pachytene oocytes appear during stage 36 and 38. Diplotene oocytes occur at stage 40. Folliculogenesis occurs 10 days after hatching. Follicles having a polymorphic membrana granulosa consisting of small, intermediate, and large round cells are found in 1‐month‐old hatchlings, and pyriform cells are observed in the granulosa of the ovary of 2‐month‐old hatchlings. The number of germ cells increases as development of the ovary proceeds. At oviposition, ∼236 and 244 germ cells were counted in right and left ovaries, respectively, and there was a manyfold increase in their number (to 4,234 and 4,294) at hatching. Mitotic germ cells are more abundant at stage 34, and no mitotic germ cells are seen after hatching.Histochemical localization of of ‐3β‐HSDH and G‐6‐PDH activity is seen in the medulla of the ovary after sexual differentiation (stage 36), which indicates that the medulla of the ovary is the site of steroidogenesis. intensity of the enzyme activity remains more or less the same in the ovary up to 1 month after hatching and begins to increase thereafter. © 1994 Wiley‐Liss, Inc.
Unique locomotory mechanism of Mermis nigrescens, a large nematode that crawls over soil and climbs through vegetation
Authors: Gans Carl , Burr A. H. Jay 
Published: February 2005

AbstractFemales of Mermis nigrescens, a nematode parasitic on grasshoppers, climb through terrestrial vegetation where they lay their eggs. The 100‐mm‐long body of these nematodes bridges gaps in this three‐dimensional substratum, and crawls efficiently over planar surfaces. The nematodes do not use the classical undulant pattern of nematode locomotion as one coordinated unit; instead they propel themselves in several independent, locally controlled zones that propagate posteriorly. A repeated motion of their anterior end laces the body around fixed objects at which force may be applied. Propulsive force is applied to objects as the body glides past the contact site. Intermediate loops are elevated above the surface where they cannot contribute to propulsion. These loops rise and fall with time due to varying differences in propulsive forces between the contact sites.Forces are applied to the objects by internally generated bending couples that are propagated along the trunk, propelling the body in a cam‐follower mechanism. Bending couples are generated by the contraction of ventral or dorsal longitudinal muscle bands that apply compressive force to the cuticle. The muscle bands, consisting of a single layer of obliquely striated muscle cells, are closely applied to the cuticle and are separated from it only by a fibrous basal lamina and a thin extension of a hypodermal cell. The myofilaments of each sarcomere are parallel to the body axis and attached perpendicularly via dense bodies (z‐line equivalents) to the basal lamina, which in turn is fixed to the cuticle via filaments passing through the hypodermal cytoplasm, Consequently, forces are transmitted laterally to the cuticle over the entire length of the muscle, compressing it parallel to the surface without need for attachment to the terminal ends of the muscle cells. Thus the muscles are engineered for local control of bending and avoidance of buckling. There is evidence that the motor nervous system of Mermis may not be as simple as in classical nematode examples, which may explain why Mermis is capable of a much more localized control of locomotory motion. © 1994 Wiley‐Liss, Inc.
Development of craniofacial musculature inMonodelphis domestica(marsupialia, didelphidae)
Authors: Smith Kathleen K. 
Published: February 2005

AbstractDevelopment of craniofacial muscles ofMonodelphis domestica(Marsupialia, Didelphidae) is described. In a period of 4–6 days all craniofacial muscles inM. domesticaprogress from myoblast condensation, to striated myofibers that are aligned in the direction of adult muscles and possess multiple, lateral nuclei. This process begins 1 to 2 days before birth and continues during the first few days after birth. Compared to other aspects of cranial development, muscle development inM. domesticais rapid. This rapid and more or less simultaneous emergence of craniofacial muscles differs from the previously described pattern of development of the cranial skeleton in marsupials, which displays a mosaic of acceleration and deceleration of regions and individual elements. Unlike the skeletal system, craniofacial muscles show no evidence of regional specialization during development.M. domesticaresembles eutherian mammals in the relatively rapid and more or less simultaneous differentiation of all craniofacial muscles. It differs from eutherian taxa in that most stages of myogenesis occur postnatally, following the onset of function. The timing of the development of muscular and skeletal structures is compared and it is concluded that the relatively early development of muscle is not reflected by any particular acceleration of the differentiation or growth of skeletal structures. Finally, the difficulties in accounting for complex internal arrangements of muscles such as the tongue, given current models of myogenesis are summarized. © 1994 Wiley‐Liss, Inc.
Kinematic analysis of jaw protrusion in orectolobiform sharks: A new mechanism for jaw protrusion in elasmobranchs
Authors: Wu Ernest H. 
Published: February 2005

AbstractJaw protrusion is an important component of prey capture in fishes, although the mechanics of protrusion have thus far been studied largely in teleosts. Elasmobranchs are also able to protrude their jaws (Tricas and McCosker [1984] Proc. Cal. Acad. Sci. 43: 221–238; Tricas [1985] Mem. S. Calif. Acad. Sci. 8:81–91.; Frazzetta and Prange [1987] Copeia 4:979–993). Several related features of the feeding apparatus contribute to jaw protrusion in sharks. Labial cartilages form an extendible series attached dorsally to the anterolateral face of the palatoquadrate and ventrally to the anteroventral surface of Meckel's cartilage. The labial cartilage chain swings anterolaterally as the lower jaw is depressed, thrusting the labial margins forward to form a circular oral opening and displacing the jaw apparatus towards the food; this pattern is analogous to halecomorph and primitive actinopterygian fishes in which the maxilla swings forward (Lauder [1979] J. Zool. Lond. 187:543–578). The palatoquadrate and Meckel's cartilage also project anteriorly and represent the major contribution to protrusion. These movements occur simultaneously with enlargement of the oral cavity to generate suction. The wobbegong sharks (Orectolobidae) are specialized for jaw protrusion. The spotted wobbegong protrudes its jaw by 33% of its chondrocranial length using two different mechanical systems. In the first mechanism of jaw protrusion, the intermandibularis and interhyoideus muscles medially compress the lower jaw and hyomandibulae. Compression of the lower jaw results in a more acute symphyseal angle so that the anteroposterior alignment of the lower jaw increases due to the rotation of each lower jaw towards a saggital orientation. Distal compression of the hyomandibulae at their attachments to the jaws swings the jaws forward. The second mechanism involves rotation of the ceratohyal around a posterior process of the lower jaw, pushing the hyomandibulae anteroventrally, thereby pushing the jaw articulation ventrally and anteriorly to protrude the jaws. © 1994 Wiley‐Liss, Inc.
Olfactory organ of acipenseriformes and comparison with other actinopterygians: Patterns of diversity
Authors: Chen Xin‐Yu , Arratia Gloria 
Published: February 2005

AbstractThe position and structure of the olfactory organ and its openings vary among actinopterygians. The anterior nasal opening is a simple perforation in the skin in many extant actinopterygians (e.g., acipenseriforms, lepisosteids, and primitive Recent teleosts) and represents the primitive condition. Polypterids and Amia each exhibit a derived condition, in which the anterior nasal opening extends into a tube. The olfactory organ is relatively far away from the anterior end of the elongate rostrum in acipenseriforms, whereas the olfactory organs are closer to the anterior end of the snout in extant actinopterygians (e.g., polypterids, lepisosteids, and amiids). In adults, olfactory organs are cuplike structures in most actinopterygians, but these organs are tubelike in polypterids. Among extant actinopterygians, a nasal diverticulum is present only in polypterids. Teleosts have accessory nasal sacs, but chondrosteans, polypterids, lepisosteids, and amiids lack them.The olfactory rosette is formed by primary folds or lamellae that may be placed anterior, lateral, posterior, and/or medial to the axis of the organ. Large acipenserids have 20–32 lamellae, polyodontids have 13–18 lamellae, lepisosteids have 8–10 lamellae, and Amia may have over 100. In teleosts, the number of lamellae varies from none or a few to over 200. Secondary lamellae are present in acipenseriforms, lepisosteids, and some advanced teleosts; secondary lamellae are interpreted as independently acquired in these lineages. Secondary lamellae are absent in Amia and primitive teleosts such as Elops and Hiodon. Tertiary lamellae are present in Acipenser oxyrhynchus. The arrangement of the primary lamellae in relation to the axis of the organ results in at least 11 patterns of the olfactory rosette in actinopterygians. Lamellae that are enclosed in a tubelike sac and that have an anteromedial diverticulum are specializations of polypterids. Primary lamellae anterior, lateral, and posterior to an elongate axis are characteristic of lepisosteids. The presence of primary lamellae lateral, medial, and posterior to an elongate olfactory axis is a synapomorphy of Halecomorpha (Amia plus teleosts). The absence of secondary lamellae is a synapomorphy of Halecomorpha. © 1994 Wiley‐Liss, Inc.