bluuebunny/crossref_metadata_2025 huggingface dataset:
Lungs of Polypterus and Erpetoichthys
Authors: Lechleuthner A. , Schumacher U. , Negele R. D. , Welsch U.
Published: February 2005

The wall of the asymmetrical saclike lungs of the fishes Polypterus and Erpetoichthys consists of several functionally different tissue layers. Their lumen is lined by a surface epithelium composed of (1) highly attenuated cells, termed pneumocytes I; (2) pneumocytes II with lamellar bodies, presumably indicating surfactant production; (3) mucous cells; and (4) ciliated cells. Underlying the pneumocytes I is a dense capillary net. The thin continuous endothelium of this net, together with the pneumocytes I, constitute the very thin blood‐air barrier. The basement membrane of epithelium and endothelium fuse in the area of the blood‐air barrier (thickness 210 m̈m). Secretory and ciliary cells form longitudinal rows in the epithelium. Below the zone with a gas‐exchanging tissue, a layer of connective tissue containing collagen and special elastic fibers occurs. The blood vessels that give rise to or drain the superficial capillary plexus are located in this connective tissue. The outermost layer of the lung consists of muscle cells, a narrow inner zone with smooth muscle cells, and an outer, broader zone with cross‐striated muscle cells. The lung is innervated by myelinated and nonmyelinated nerve fibers. The morphology of the gas‐exchange tissue in the lungs of these primitive bony fish is fundamentally very similar to that of the lungs of tetrapod vertebrates. The morphologic observations are in close agreement with physiologic data, disclosing well‐developed respiratory capacities. Structural simplicity can be regarded as a model from which the lungs of the higher vertebrates derived. In addition to respiratory function, the lungs seem also to have hydrostatic tasks.
Immunofluorescent, immunogold, and electrophoretic studies for desmin in embryonic hearts of normal and cardiac mutant mexican axolotls, Ambystoma mexicanum
Authors: Shen Pei‐Shen , Lemanski Larry F.
Published: February 2005

Recessive mutant gene c for “cardiac nonfunction” in axolotls results in an absence of normal heart contractions in affected embryos due to a failure of myofibril formation. In the present study, the intermediate filament protein, desmin, is compared in developing normal and mutant hearts by means of two‐dimensional gel electrophoresis, immunofluorescent microscopy, and immunoelectron microscopy. Tissues were fixed in periodate‐lysine‐paraformaldehyde or paraformaldehyde‐glutaraldehyde solutions and rapidly frozen or embedded in Lowicryl resin. Frozen sections stained with FITC‐conjugated antibodies by an indirect approach revealed that desmin is localized in the I‐band regions of adult cardiac myofibrils. In normal embryonic hearts at stage 32 (preheartbeat) desmin is localized as “spots” or amorphous collections in the cells. As development progresses to stage 35, staining for desmin in normal hearts becomes more intense with localization being most pronounced at the cell peripheries. By stage 41 most of the desmin in normal hearts is localized in the I band areas of the organized myofibrils and the staining of amorphous areas is much less prominent. During early development, the distribution of desmin in mutant hearts is similar to normal. However, while most of the desmin in normal organs at stage 41 is associated with myofibrils, the staining remains diffuse in mutants. Twodimensional gel electrophoresis reveals comparable patterns for desmin from normal and mutant hearts. Immunogold staining shows desmin localization to be between the myofibrils and around the I‐band regions in adult cardiac muscle and in stage 41 normal embryonic hearts. Immunogold staining confirms a diffuse distribution of desmin in mutant hearts.
Ontogeny of gut morphology in the white shrimp Penaeus setiferus (Decapoda, Penaeidae)
Authors: Lovett Donald L. , Felder Darryl L.
Published: February 2005

Ontogeny of the gut in Penaeus setiferus was investigated by reconstruction of serial sections examined by light microscopy. Development of the gut into the adult form is protracted over several weeks beyond metamorphosis in steps that may be directly related to the unique postlarval life history of Penaeus. The gastric mill is lacking in larval stages of P. setiferus. In protozoeal stages Z1‐Z3, the pyloric ampullae are blind sacs that do not communicate with the midgut. The gland filter first appears in mysis stage M2. The gastric mill in early postlarval (PL) stages consists of poorly chitinized lobes with flexible setae. By PL21 the ossicles of the gastric mill are rigid and setae are replaced by spine‐like denticles, but even by PL35 the gastric mill is neither as massive nor heavily chitinized as in adults. During the mysis stages and early PL stages, the hepatopancreas communicates freely with both the foregut and the midgut trunk. By PL35 the hepatopancreatic ducts are essentially isolated from the remainder of the midgut by foregut ossicles.

The midgut in Z1 consists of two pairs of simple caeca and the midgut trunk. During larval growth, each of the lateral midgut caeca develops into a number of lobes. After metamorphosis these lobes begin to ramify into small‐diameter tubules, and by PL35 have completely ramified into the hepatopancreas of adults. From M1 to PL4, the anterior midgut caeca decrease in absolute size and become a single anterior diverticulum. The posterior midgut diverticulum first appears in PL21 as a simple sac and thereafter increases in size and complexity.
Connecting bridges between axoneme and other components in the sperm tail of some insects
Authors: Afzelius Björn A. , Dallai R.
Published: February 2005

Spermatozoa from three insect groups were examined by electron microscopy and found to have bridges that connect some of the axonemal doublets with either the two mitochondrial derivatives or, in the phasmids, the so‐called laminated bodies. Within Hemiptera Heteroptera the bridges extend from doublet Nos. 1 and 5, within chrysopid neuropterans from doublet Nos. 2 and 5, and in the phasmids from axonemal doublet Nos. 2 and 4. Bridges were looked for in spermatozoa from several other insect groups but not found. The bridges in the chrysopids are regularly curved rather than straight. While bridges in heteropterans and chrysopids were seen in spermatozoa fixed with “standard fixatives,” those in the phasmids were distinctly resolved only in spermatozoa that had been fixed with a tannic acidcontaining fixative. In spite of these differences, it is conceivable that the bridges in these three insect taxa are all derived from similar, faint, bridge‐like connections that sometimes can be seen to extend from all or many doublets toward the axonemal sheath of the early insect spermatid. These bridges or bridge‐like structures might have a morphogenic function in that they may specify the location of the mitochondria later to become mitochondrial derivatives or, in the phasmids, of the laminated bodies.
Ultrastructure of the adenohypophysis in the anadromous sea lamprey, Petromyzon marinus, during metamorphosis
Authors: Wright Glenda M.
Published: February 2005

The ultrastructural changes occurring in the adenohypophysis (AH) of the anadromous sea lamprey, Petromyzon marinus, during metamorphosis (stages one through seven) were examined. The rostral pars distalis initially contains one granulated (secretory) cell type A and one nongranulated type I cell. A second granulated cell (type B) appears during the later stages (stages six and seven) of metamorphosis. The most pronounced ultrastructural changes take place in the caudal pars distalis (CPD). Initially, most cells (80–90%) are nongranulated cells type II and some type I. Granulated type C and D cells form the remainder of the CPD. Almost all cells during stages three and four demonstrate a marked increase in synthetic activity evident by conspicuous Golgi regions, abundant rough endoplasmic reticulum (RER), and increased cell volume. Most cells are sparsely granulated. Secretory cell types C and D and, two new cell types, E and F, are present. Synthetic activity subsides by stage five. Most cells (80–90%) during stages five through seven are granulated. Type E are most prevalent with variable numbers of types C and D and few type F. Nongranulated cells now represent only 10–20% of the CPD. The increase in granulated cells occurs at the expense of type II cells that differentiate into granulated cell types. The fine structure of the pars intermedia throughout metamorphosis remains similar to that of the larva. Most cells are granulated, highly vesiculated type G cells. A few nongranulated type I cells are also present. The functional significance of the secretory cells in the AH is related to the requirement for an intact pituitary gland for the initiation and completion of metamorphosis.
Segregation of primordial germ cells: Their numbers and fate during early development of Barbus conchonius (Cyprinidae, Teleostei) as indicated by 3H‐thymidine incorporation
Authors: Timmermans L. P. M. , Taverne N.
Published: February 2005

3H‐Thymidine incorporation experiments in Barbus conchonius showed that presumptive primordial germ cells (PGCs) terminated their mitotic activity between midepibolys, and late epiboly. At the ten‐somite stage, shortly after labeling of PGCs by uptake of 3H‐thymidine became arrested, they could be recognized by their relatively large size and large nucleus. They were located in two longitudinal rows of cells between mesoderm and periblast, always at the same distance to the left and right of the notochord. Contact with the endoderm was not observed before the 16‐ to 23‐somite stage. The numbers of PGCs were small (mean number, 18–19) and remained small for nearly 3 weeks. Mitotic activity was not observed in PGCs during that period; thereafter, rapid proliferation began. There is no evidence for active migration of PGCs; it is assumed that they are merely translocated passively together with their surrounding tissues. No specific constituents were detected with histochemical methods for glycogen, alkaline phosphatase, and RNA. Electron microscopy revealed the presence of “nuage” around the nucleus of PGCs. This material corresponded with perinuclear dense bodies as seen with light microscopy from the 19‐somite stage onward.

It is concluded that presumptive PGCs segregate from the somatic cells between midepiboly and late epiboly, before the three germ layers have been formed, and that locations of PGCs in the endodermal or mesodermal layer may be merely transitory stages during their translocation toward the gonadal primordia.
Cellular structure and ultrastructure of the black coral Antipathes aperta: 1. Organization of the tentacular epidermis and nervous system
Authors: Goldberg Walter M. , Taylor George T.
Published: February 2005

The tentacular epidermis of the black coral Antipathes aperta is organized into three distinct regions, containing at least nine different types of cells. The outermost region is dominated by spirocytes along with two types of nematocytes, organized into discrete wart‐like batteries. The two nematocyte types both contain microbasic b‐mastigophore nematocysts. The outer boundary of the wart is marked by the presence of both spumous and vesicular mucus cells. The ciliation of the wart is contributed principally by the spirocytes. Warts are enveloped and separated from one another by an unusual neurosensory cell complex that extends from the tentacular surface to the mesogleal connective tissue foundation. Funnel‐like, flagellated cells composing the complex connect with ganglion cells composing the dominant portion of the nerve net system. Branches of this complex also penetrate the central portion of the wart, making direct contact with the cnidae. The tentacular mid‐region is composed of nematocytes and spirocytes in various stages of maturation, along with epitheliomuscular cell (EMC) somata. The EMC's narrow apically extend toward the tentacle surface, forming contacts with the cnidae. The basal end of the EMC expands to form the larger portion of the tentacular musculature. The inner region of tentacular epidermis is marked by a neuromuscular complex sheathed by extensions of mesoglea. The ganglion cells occur as a plexus deep within the tentacle and form polarized junctions with the EMC's, but neuromuscular synapses are not well enough defined for documentation. Polarized synapses lacking well‐defined membrane thickenings characterize the interneuronal junctions. Granular cells lining the mesogleal surface appear to be responsible for mesogleal fibrillogenesis.
Cellular structure and ultrastructure of the black coral Antipathes aperta: 2. The gastrodermis and its collar cells
Authors: Goldberg Walter M. , Taylor George T.
Published: February 2005

The gastrodermis of the black coral Antipathes aperta is associated with eight distinct types of cells, including two types of microbasic b‐mastigophores (nematocysts), spumous and vesicular mucus cells, and ganglion cells that are essentially the same as in the epidermis. Three additional types of cells are unique to the gastrodermis, and are readily distinguished from those of the epidermis by their electron‐opaque inclusions. These include lipoidal cells, zymogen digestive cells, and an unusual type of epitheliomuscular collar cell. The pharyngeal region is characterized by the presence of electron‐opaque nematocysts, a scattering of zymogen cells, and a large number of collar cells. The latter are distinguished in part by the presence of dense microfibrillar processes that surround the microvilli and extend into adjacent collars. This interconnection results in the formation of an extensive pharyngeal meshwork. These collar cells are additionally distinguished by the placement of the collar and flagellum adjacent to a flared cup of cytoplasm. This portion of the cell is capable of endocytosis of relatively large unicellular prey, and apparently is capable of forming digestive vesicles as well. The pharyngeal gastrodermis grades into simple lobate septal filaments toward the base of the coelenteron, where large, granular nematocysts all but replace the smaller electron‐opaque types Collar cells are found here as well, but in fewer numbers compared to the zymogen cells. Ultrastructural results are compared with those of other coelenterates and discussed in terms of food and modes of nutrition.
Structure, function, and evolutionary significance of the reproductive system in males ofHebrus ruficepsandH. pusillus(heteroptera, gerromorpha, hebridae)
Authors: Heming‐van Battum Karin E. , Heming B. S.
Published: February 2005

In Holland, bugs of the speciesHebrus pusillusandH. ruficepshave one generation per year and overwinter as unmated adults. Males have two testes with two follicles + vasa efferentia each, paired vasa deferentia and seminal vesicles, an ejaculatory duct, and a protrusible phallus comprising an articulatory apparatus, phallotheca, endosoma, and paired claspers. The skeletomusculature of this system is described (it has 12 paired and four unpaired muscles) and its functions in generating and transferring sperm (summarized in Figs. 70–75) are reconstructed from study of living bugs, dissections, whole mounts, and serial sections.

Males of both species produce sperm >2 mm long from stem spermatogonia in the germarium of each follicle. Initial definitive spermatogonia divide synchronously three times to form clones of eight, interconnected, primary spermatocytes. These enlarge up to 43‐fold in males ofH. pusillusand 78‐fold in those ofH. ruficeps, undergo meiosis, and, after adult emergence, complete their differentiation into bundles of 32 sperm which coil transversely about the periphery of each follicle at its base. These begin to enter the vasa efferentia in mid August, rupture, and release their sperm into the seminal vesicles where they are stored overwinter. Most spermatocyte and spermatid cysts remaining in the testes degenerate in fall, leaving only stem spermatogonia and a few early spermatocysts in the germaria.

Males ofH. pusillusbegin to mate the first warm days of spring but only the most persistent succeed. A male jumps on the back of a female, induces her to lower her ovipositor, and, within 12 min (@ 18–24°C), introduces the endosoma of his phallus up its shaft and fills his seminal duct with sperm. The female draws this into her gynatrial sac at the end of copulation and transfers it into her spermatheca in about 30 min, the sperm reversing themselves within it so that their heads face towards its mouth. The male may stay on her back for up to 2 hours and may copulate again up to three times before leaving to mate with other females.

Males ofH. pusillusmay be sexually active for months after overwintering, because spermatogonia in their germaria reactivate in spring to produce additional sperm. Those ofH. ruficepsdo not and males mate successfully only until their supply of overwintered sperm is exhausted.

The chromosome complement ofH. pusillusmales is 2N = 22 + XY. The X and Y chromosomes are of unequal length, form a pseudo pair at metaphase I, and segregate to opposite poles at anaphase I—the first instance of pre‐reductional segregation of sex chromosomes to be recorded in the Gerromorpha. The chromosome complement ofH. ruficepsmay be 2N = 24 + XO but the nature of two chromosomes was not resolved. The single X segregates to half the spermatids at anaphase II.
Ultrastructure of neuroendocrine cells in the lungs of three anuran species
Authors: Goniakowska‐Witalińska L. , Cutz E.
Published: February 2005

Neuroendocrine cells in the lungs of three species of anurans, Bombina variegata, Bufo bufo and Bu. viridis, occur both as single cells and in the form of neuroepithelial bodies. Neuroendocrine cells are covered by ciliated cells or pneumocytes, which separate them from the lumen of the lung. Neuroepithelial bodies are dispersed in the apical part of the main septa of lungs of Bo. variegata and Bu. bufo or are situated on special protrusions of septa in the lungs of Bu. viridis. Neuroepithelial bodies are innervated by intraepithelial nerve endings of afferent and efferent types.
Comparative buccal anatomy in Helisoma (mollusca, pulmonata, basommatophora)
Authors: Smith David A.
Published: February 2005

Dissections were performed to document buccal anatomy in three species of the pulmonate genus Helisoma Swainson, 1840. The 28 muscles which are responsible for radular feeding in these animals are organized in three concentric and integrated envelopes. The deepest of these includes muscles which manipulate the radula about the odontophoral cartilage. Elements of the middle envelope direct movements of the cartilage within the buccal cavity, and muscles of the outer envelope control movements of the buccal mass within the cephalic haemocoel. Motion analysis by videomicrography showed that muscles of the middle and outer envelopes contribute to the action of radular feeding by acting as antagonists to other muscles and to hydrostatic elements of the buccal apparatus. Observations of radular dentition showed that although each of the three species examined has a unique radula, especially with regard to the specific details of tooth shape, all resemble a radula characteristic of the Planorbidae with regard to other, more general, aspects of ribbon architecture.
Torsion in the asteroid ray
Authors: O'neill Patricia L.
Published: February 2005

Although torsion (axial twisting) is rare in living structures, some starfish routinely use ray torsion in the righting process. This study examined the torsional properties of the ray and dorsal body wall of Echinaster spinulosus (Echinodermata: Asteroida: Spinulosidae). The body wall of the ray is composed of a reticular skeleton composed of CaCO3 ossicles sandwiched between collagenous layers in which the fibers are orthogonally oriented. G, the shear modulus of the dorsal body wall, determined from a torsion pendulum, was 95.3 MPa, and damping was extremely pronounced (Δ = 1.36). The torque‐rotation curve was J‐shaped, and G determined from this data was 176 MPa. Torsional stress relaxation was rapid, with the relaxation spectrum skewed to the left and τmax = 2.3 for anaesthetized tissue and 2.7 for unanaesthetized tissue.

Analysis of ray geometry showed that the ambulacral groove reduced torsional stiffness by about two orders of magnitude compared to an ungrooved ray. Ray taper reduced the stiffness of the tip relative to the root. The shear stress distribution determined for the ray cross‐section showed stress concentrations around the ambulacral arch, the outer body wall surface, and the inner body wall surface. The ossicles are situated to minimize torsional stiffness of the ray.
Vasculature of the head and respiratory organs in an obligate air‐breathing fish, the swamp eel Monopterus (=Amphipnous) cuchia
Authors: Munshi J. S. D. , Ghosh T. K. , Ojha J. , Olson K. R.
Published: February 2005

Methyl methacrylate vascular corrosion replicas were used to examine the macrocirculation in the head region and the microcirculation of respiratory vessels in the air‐breathing swamp eel Monopterus cuchia. Fixed respiratory tissue was also examined by SEM to verify capillary orientation. The respiratory and systemic circulations are only partially separated, presumably resulting in supply of mixed oxygenated and venous blood to the tissues. A long ventral aorta gives rise directly to the coronary and hypobranchial arteries. Two large shunt vessels connect the ventral aorta to the dorsal aorta, whereas the remaining ventral aortic flow goes to the respiratory islets and gills. Only two pairs of vestigial gill arches remain, equivalent to the second and third arches, yet five pairs of aortic arches were identified. Most aortic arches supply the respiratory islets. Respiratory islet capillaries are tightly coiled spirals with only a fraction of their total length in contact with the respiratory epithelium. Valve‐like endothelial cells delimit the capillary spirals and are unlike endothelial cells in other vertebrates. The gills are highly modified in that the lamellae are reduced to a single‐channel capillary with a characteristic three‐dimensional zig‐zag pathway. There are no arterio‐arterial lamellar shunts, although the afferent branchial artery supplying the gill arches also supplies respiratory islets distally. A modified interlamellar filamental vasculature is present in gill tissue but absent or greatly reduced in the respiratory islets. The macro‐ and micro‐circulatory systems of M. cuchia have been considerably modified presumably to accommodate aerial respiration. Some of these modifications involve retention of primitive vessel types, whereas others, especially in the microcirculation, incorporate new architectural designs some of whose functions are not readily apparent.
Structure of the accessory reproductive glands of the male migratory grasshopper, Melanoplus sanguinipes
Authors: Couche Graham A. , Gillott Cedric
Published: February 2005

The accessory reproductive glands of Melanoplus sanguinipes comprise two bilateral masses of 16 tubules each, distinguishable in sexually mature insects as four white, ten short hyaline, one long hyaline, and a seminal vesicle. Over most of its length, the wall of each tubule consists of a simple glandular epithelium resting on a basal lamina, surrounded by a thin layer of circular muscle. However, near the junction with the ejaculatory duct, the wall of each tubule has a much thickened circular muscle layer and squamous or cuboidal epithelium, the region serving to regulate movement of secretion into the ejaculatory duct. Interdigitation of adjacent epithelial cells is common, and several kinds of specialized junctions occur. In the glandular region, all epithelial cells appear the same and may be flattened, cuboidal, or columnar depending on the tubule type. Except for those of the seminal vesicle, the glandular epithelial cells share ultrastructural features typical of cells engaged in the synthesis of protein for export. Despite these general similarities, in most instances subtle differences occur in the cellular ultrastructure of the epithelia of each tubule and in the appearance of their luminal secretions, suggesting that the tubules are functionally specialized.
Golgi study of the anterior dorsal ventricular ridge in a lizard. II. Neuronal cytodifferentiation
Authors: Díaz C. , Yanes C. , Medina L. , Trujillo C. M. , Monzón M. , Puelles L.
Published: February 2005

The development of the morphologic features of neurons in the anterior dorsal ventricular ridge (ADVR) has been followed in Golgi preparations from the lizard Gallotia galloti between embryonic stage 32 and post‐eclosion stages of specimens 3.6–4.5 cm in length. The differentiation sequence of multipolar and bitufted neurons was established. Dendritic growth cones are present after stage 34. Filiform dendritic processes are replaced later on by spines. Clusters of neurons first appear at stage 39 in the periventricular zone, the cells becoming Golgi‐impregnated in pairs. After hatching, the number of impregnated cells per cluster increases.
Structure of the temporal organ of the Japanese house centipede, Thereuonema hilgendorfi Verhoeff
Authors: Yamana Kenjiro , Toh Yoshihiro
Published: February 2005

The ultrastructure of the temporal organ of the Japanese house centipede, Thereuonema hilgendorfi Verhoeff (Chilopoda), has been examined. The temporal organ of this species is known to be a carbon dioxide receptor. It appears externally as a small protuberance with a small opening (5 μm) on its summit. There is a small cuticle‐lined cavity beneath the protuberance, and a mushroom‐shaped projection protrudes from the base of the cavity into its interior. Below the cavity is an encapsulated, bulb‐shaped cellular mass (sensory bulb), which contains about ten receptor cells and 100 supporting cells. Nuclei of both receptor and supporting cells occur basally in the sensory bulb. Each receptor cell has a single dendrite, which gives rise to a pair of sensory cilia. The cilia enter the mushroom‐shaped projection, and course along the inner surface of its calyx. The supporting cells have distal processes, which accompany the cilia into the calyx. The surface cuticle of the calyx consists of a fabric of fibrils, but in not layered like the cuticular integument. The fabric is permeable to water. The observed structure is discussed in relation to carbon dioxide reception and in comparison with the structure of olfactory receptors and hygroreceptors.
Comparative studies on the vascular organization of carotid labyrinths of anurans and caudates
Authors: Kusakabe Tatsumi
Published: February 2005

The three‐dimensional structures of the carotid labyrinth in five species of anurans representing four families (Rana nigromaculata, Rana catesbeiana, Bufo japonicus, Hyla arborea, and Xenopus laevis), and three species of caudates representing three families (Cynops pyrrhogaster, Hynobius nebulosus, Ambystoma mexicanum) were compared using vascular corrosion castings and scanning electron microscopy (SEM). Anuran carotid labyrinths are spherical in shape and are classified into two groups according to the origin of the external and internal carotid arteries. One group, which included Rana, Hyla, and Bufo, is characterized by the presence of a vascular ring at the proximal end and some vascular routes at the distal end of the labyrinth. The external and internal carotid arteries originate from these structures. The other group, which includes only Xenopus, is characterized by the external carotid artery opening directly from the central chamber or the common carotid artery, and by the internal carotid artery originating from within the vascular maze. The vascular maze is most complex in Xenopus, less so in Rana and Bufo, and simplest in Hyla. The carotid labyrinths in Cynops and Hynobius are oblong in shape. The fundamental organization in salamanders is similar to that in anurans. The vascular maze, however, is much simpler than in Hyla. There is no specialized swelling in Ambystoma mexicanum. The present findings suggest that most amphibian carotid labyrinths have the appropriate architecture for controlling vascular tone.
Functional organization of the arctiid moth tymbal (insecta, lepidoptera)
Authors: Fullard J. H. , Heller B.
Published: February 2005

The exoskeletal morphology, muscular organization, and innervation patterns of the tymbals of seven sound‐producing species of tiger moths (Arctiidae) were compared with the undifferentiated episterna of two silent species. At least three muscles are involved in sound production: the tymbal muscle, pv2, and the accessory muscles, pvl and/or pv6. All of the tymbal muscles are innervated by the IIIN2a branch of the metathoracic leg nerve, which contains two axons larger than the others. Backfills of the tymbal branch of the IIIN2a reveal a medial sensory neuropil and a population of five ipsilateral motor neurons whose somata are clustered into three groups along the anterior edge of the metathoracic ganglion. The dendritic arborizations of the motor neurons extend to the ganglionic midline but are separate from one part of the auditory neuropil observed in other noctuoids. The study concludes that the arctiid tymbal reveals only minor modifications (e.g., cuticle thinning) of the episterna of silent moths and represents a primitive form of the tymbal compared to those of the Cicadidae.
The chiton gill: Ultrastructure in Chiton olivaceus (Mollusca, Polyplacophora)
Authors: Fischer Franz Peter , Alger Monika , Cieslar Daniela , Krafczyk Hans‐Ulrich
Published: February 2005

Gills of Chiton olivaceus, a primitive mollusc, are relatively simple in their structure and ultrastructure but are well adapted to a life in the intertidal zone. In contrast to some other molluscs, there is no differentiation of the gill epithelium into functional regions other than respiratory ones. Ciliation of the epithelium in certain areas may optimize water flow from the outer to the inner part of the mantle cavity. The hemolymph sinuses are oriented so that hemolymph flows in the opposite direction. Interstitial cells link epithelial cells with nerve endings. Muscle cells as well as the collagenous matrix in the connective tissue differ within the main gill axis and the lateral lamellae. The life cycle of immunoactive cells within the connective tissue and the hemolymph is described.
The digestive system of the fish ectoparasite Dolops ranarum (Crustacea: Branchiura)
Authors: Avenant‐Oldewage Annemarie , van As J. G.
Published: February 2005

Reconstructions from serial sections reveal that the digestive system consists of a pharynx esophagus, crop, midgut, and rectum. Two main stems from the branched enteral diverticula are connected to the lateral regions of the crop by right rind left arms. Glandular tissue surrounds the enteral diverticula proximally. A strong sphincter separates the crop and midgut, whereas the midgut and rectum are separated by a weak sphincter. Cuboidal epithelium lines the pharynx, esophagus, crop, and rectum, whereas cuboidal and club‐shaped epithelia line the midgut. The cuboidal cells possess elongated nuclei and numerous vacuoles, suggesting that absorption takes place in the midgut.
Differential scaling of the long bones in the terrestrial carnivora and other mammals
Authors: Bertram John E. A. , Biewener Andrew A.
Published: February 2005

We measured the lengths and diameters of four long bones from 118 terrestrial carnivoran species using museum specimens. Though intrafamilial regressions scaled linearly, nearly all intraordinal regressions scaled non‐linearly. The observed non‐linear scaling of bone dimensions within this order results from a systematic decrease in intrafamilial allometric slope with increasing body size. A change in limb posture (more upright in larger species) to maintain similar peak bone stresses may allow the nearly isometric scaling of skeletal dimensions observed in smaller sized mammals (below about 100 kg). However, strong positive allometry is consistently observed in a number of large terrestrial mammals (the largest Carnivora, the large Bovidae, and the Ceratomorpha). This suggests that the capacity to compensate for size increases through alteration of limb posture is limited in extremely large‐sized mammals, such that radical changes in bone shape are required to maintain similar levels of peak bone stress.
The relationship of pores and mammillae on the inner surface of the eggshell of the alligator (Alligator mississippiensis)
Authors: Wink Carole S. , Elsey Ruth M. , Bouvier Marianne
Published: February 2005

The morphology of the eggshell of the alligator, Alligator mississippiensis, is similar to that of birds. In many avian species there is a positive linear correlation between the numbers of pores and mammillae on the inner surfaces of eggshells, indicating that the distribution and density of mammillae may determine the porosity of the shell. It is not known, however, if a relationship exists between pores and mammillae on the shell of the alligator. Using a scanning electron microscope, we counted pores and mammillae on the inner surfaces of pieces of shell from the middle of fertile and infertile eggs from wild and captive, pen‐reared alligators. Data were analyzed by ANOVA, Duncan's multiple range tests and linear regression equations. Results demonstrate a positive linear correlation between the numbers of pores and mammillae on the shells of unincubated fertile and infertile eggs from wild and captive alligators; however, there is no correlation between pores and mammillae on shells of eggs that were incubated for 55 days. It is suggested that initially the porosity of the eggshell of the alligator is related to the density of mammillae on the inner surface of the shell and that erosion of the shell during incubation destroys the original relationship between pores and mammillae.
Histochemical and ultrastructural study of the digestive tract of the tortoise Testudo graeca (Testudines)
Authors: Perez‐Tomas R. , Ballesta J. , Madrid J. F. , Pastor L. M. , Hernandez F.
Published: February 2005

The digestive tract of the tortoise Testudo graeca (Testudines) was investigated by means of light and electron microscopy. The esophagus of T. graeca was lined by two types of epithelium: non‐keratinized stratified squamous in the upper portion and stratified columnar in the lower. The lamina propria of the esophagus contained tubular or tubuloacinar glands. The mucosa of the stomach showed similar characteristics to those of other reptiles. The small intestine exhibited longitudinal folds lined by absorptive and goblet cells. The large intestine was lined by columnar mucous cells. Within the lamina propria of the large intestine, masses of 10–15 epithelial cells connecting with the surface epithelium by means of slender cytoplasmic processes were observed. A battery of six lectins (Con‐A, PNA, WGA, DBA, SBA, and LTA) was used to identify the epithelial mucins. WGA and DBA reacted with all types of mucous cells throughout the alimentary canal. PNA was only unreactive in the intestine, LTA in the esophagus, and SBA in the large intestine. These results indicate a similar lectin‐binding pattern throughout the gut of T. graeca.
Ultrastructure of the blood vessels in the harderian gland of the hamster (mesocricetus auratus): Existence of sinusoids
Authors: Menendez‐Pelaez A. , Tolivia D. , Rodriguez‐Colunga M. J. , Reiter R. J.
Published: February 2005

The Harderian gland blood supply of female and male hamsters was studied using light and electron microscopy. A profuse vascularization surrounding secretory acini was observed. Among the blood vessels, the existence of large and irregular sinusoidal capillaries was apparent. These sinusoids appeared in close association to the basal aspect of the secretory cells. Typical, small, fenestrated capillaries were also observed within the connective tissue. The existence of this particular vascularization together with other morphological features of the secretory cell basal pole suggest a possible endocrine function of these orbital glands.
Histology and ultrastructure of the gut of the black mollie (poecilia spp.), a hybrid teleost
Authors: Caceci Thomas , Hrubec Terry C.
Published: February 2005

A light and electron microscopic (TEM and SEM) study of the gut of the black mollie (Poecilia spp.) shows that the gut is a relatively undifferentiated muscular tube lined with a simple columnar epithelium. The mucosa and underlying lamina propria are formed into folds. The apices of the folds form obtuse angles at the cranial end and more acute ones caudally. The mucosal epithelium is a simple columnar sheet with PAS‐positive goblet cells interspersed throughout. The enterocytes are covered apically with uniform microvilli in most of the tract, and the plasma membrane deeply infolded basally. Mitochondria are located in the basal folds. A continuous basal lamina separates the epithelial mucosa from the underlying lamina propria. Enterocytes have a PAS‐positive Golgi apparatus in the supranuclear region. The enterocytes of the cranial and middle thirds of the gut are morphologically indistinguishable, but those in the caudal third display shorter and sparser microvilli. There is no evidence of pinocytotic activity in the enterocytes of the cranial two thirds of the gut tube, but some apical pinocytotic vesicles are seen in the cells in the caudal third. The tunica muscularis consists of two layers of smooth muscle, inner circular and outer longitudinal. We observe lateral separation of enterocytes from each other deep to the junctional complexes in the caudal and midgut regions. The gut of the mollie lacks some of the specialized cell types commonly found in other fishes. It cannot create an acidic gastric environment; overall control of digestive activity, osmolarity, and ionic balance presumably rest in the structural relationships between epithelial cells and between the epithelium and its supporting tissues. Regional specialization of cells and of the gut as a whole may confer digestive function equivalent to that found in more complicated systems.
Thymus of Rana perezi: Presence of interdigitating cells
Authors: Alvarez Rafael
Published: February 2005

In the thymus of Rana perezi, as in other anuran amphibians, there exist two different portions, cortex and medulla. In both sections epithelio‐reticular cells are observed as are lymphocytes, macrophages, and granulocytes. In addition, the medulla shows cysts and secretory, myoid, and hypertrophied epithelio‐reticular cells. In the cortex, plasma cells and interdigitating cells were also observed. Interdigitating cells make contact with lymphocytes. This finding provides morphological support for the hypothesized role of interdigitating cells in antigen presentation.
Morphological changes in the oviductal endometrium during the reproductive cycle of the tortoise,Gopherus polyphemus
Authors: Palmer Brent D. , Guillette Louis J.
Published: February 2005

The oviducts of 24 tortoises (Gopherus polyphemus) were examined using histological techniques and scanning electron microscopy to determine endometrial morphology. Measurements of endometrial characteristics (epithelial cell height, cilia length, thickness of endometrial glandular layer, and glandular diameter) in the uterus and tube (tuba uterina) were obtained to determine changes during the reproductive cycle. Epithelial cell height increases in both the uterus and the tube during vitellogenesis and remains hypertrophied during gravidity. Cilia length increases in the uterus during late vitellogenesis and gravidity, but the length of tubal cilia does not change during the reproductive cycle. The ratio of secretory to ciliated epithelial cells in the oviduct increases from quiescence to gravidity. The thickness of the glandular endometrial layer increases in both the uterus and tube during vitellogenesis. In the uterus, the glandular layer decreases in thickness during gravidity. The diameter of the uterine glands increases throughout vitellogenesis and gravidity; however, following ovulation glandular cells become depleted of secretory granules and cell height diminishes. The diameter of the tubal glands is unchanged during the reproductive cycle. Oviductal hypertrophy during vitellogenesis coincides with elevated circulating estradiol, whereas during gravidity progesterone concentrations peak (Taylor, '82, PhD Dissertation, University of Florida, Gainesville) and may induce secretion of albumen and eggshell components.
Interhemispheric connections through the pallial commissures in the brain of Podarcis hispanica and Gallotia stehlinii (Reptilia, Lacertidae)
Authors: Martíanez‐Garcíaa Fernando , Amiguet Miguel , Schwerdtfeger Walter K. , Olucha Francisco E. , Lorente María Joséa
Published: February 2005

The cells‐of‐origin and the mode and site of termination of the interhemispheric connections passing through the anterior and posterior pallial commissures in the telencephalon of two lizards (Podarcis hispanica and Gallotia stehlinii) were investigated by studying the anterograde and retrograde transport of unilaterally injected horseradish peroxidase. The commissural projections arise mainly from pyramidal cells in the medial, dorsomedial, and dorsal cortices (medial subfield). Additionally some non‐pyramidal neurons in the medial and dorsal cortices contribute to the commissural system. Medial cortex neurons project to the contralateral anterior septum through the anterior pallial commissure. The dorsomedial cortex projects contralaterally via the anterior pallial commissure to the dorsolateral septum and to the medial, dorsomedial, and dorsal cortices. The projection to the medial cortex terminates in two bands at the inner and outer border, respectively, of the cell layer; the projection to the dorsomedial and dorsal cortex ends in a zone in layer 1 which previously has been described to be Timm‐negative, and in a diffuse band in the inner half of layer 3. The medial subfield of the dorsal cortex projects through the anterior pallial commissure to the dorsomedial and dorsal cortices with a similar pattern of termination to that found for the dorsomedial cortex. The posterior pallial commissure contains only the projections from the ventral cortex to its contralateral counterpart and to the ventral part of the caudal medial cortex. The similarities found between this commissural system and the mammalian hippocampal interhemispheric connections are discussed.
Development of the extraembryonic membranes and histology of the placentae in Virginia striatula (Squamata: Serpentes)
Authors: Stewart James R.
Published: February 2005

Development of the extraembryonic membranes and their structural alignment in the formation of the four placental categories that occur in Virginia striatula is similar to that of other Serpentes. The vascularized trilaminar omphalopleure contacts the uterine epithelium early in development to form the choriovitelline placenta, which subsequently extends over the surface of the yolk to its limit at the margin of the isolated yolk mass. As in other squamates, the isolated yolk mass is separated from the yolk sac by the growth of intravitelline cells into the yolk. The bilaminar omphalopleure (ectoderm, endoderm) of the isolated yolk mass contributes the fetal epithelium of the omphaloplacenta. During formation of the omphidoplacenta, the allantois makes its initial contact with the chorion dorsal to the embryo. As the allantois expands, the chorioallantoic placenta gradually replaces the choriovitelline placenta. The terminal placental stage is defined by an extensive chorioallantoic placenta and an omphalallantoic placenta associated with the isolated yolk mass. Although similar in most aspects to the omphalallantoic placentae of other snakes, a secondary yolk cleft develops in V. striatula. This structure, which separates the outer allantoic membrane from the isolated yolk mass, has not been described in other squamates. The choriovitelline placenta and most of the surface of the chorioallantoic placenta are characterized by close vascular apposition, whereas the omphaloplacenta and omphalallantoic placenta feature uterine and fetal epithelial cell hypertrophy in the absence of fetal vascular support. A narrow zone within the chorioallantoic placenta, lying on either side of the omphalallantoic placenta, contains hypertrophied epithelial cells with supporting capillaries on both fetal and maternal aspects.
Electron microscopic observations on the vomeronasal sensory epithelium of a crotaline snake, Trimeresurus flavoviridis
Authors: Takami Shigeru , Hirosawa Kazushige
Published: February 2005

The vomeronasal sensory epithelium of a crotaline snake, Trimeresurus flavoviridis, was shown to consist of a superficial supporting cell layer and an underlying sensory cell layer composed of columns of sensory cells. The supporting cell layer consists of both supporting cells and dendrites of the underlying sensory neurons. The apical regions of sensory cell dendrites contain numerous microtubules, many elongated mitochondria, centrioles, and electron‐dense bodies. The dendrites terminate as dendritic knobs from which microvilli project into the vomeronasal lumen. Smooth vesicles are abundant in the dendritic terminals and their vicinity. Supporting cells also bear microvilli, and these cells contain large electron‐opaque granules and dense vesicles near their free surfaces. Cytoplasmic extensions of the supporting cells form a meshwork which separates dendrxites from each other in the vicinity of the luminal surface. The meshwork becomes obliterated in the infranuclear region of each supporting cell. Bipolar‐shaped sensory cells with lightly stained round nuclei contain the characteristic cell organelles of neurons and are thought to be sensory neurons. These cells are especially characterized by well‐developed lamellae of rough endoplasmic reticulum and extensive arrays of smooth endoplasmic reticulum. The perikarya of cells located in the apical region of the cell columns tend to contain larger amounts of smooth endoplasmic reticulum and lipofuscin granules than the perikarya of cells located in lower regions. Undifferentiated cells are found in the basal region of the columns. Satellite cells form the framework of the columns and are also found among neuronal elements.
Morphology of the teeth of the American alligator (Alligator mississippiensis): Fine structure and chemistry of the enamel
Authors: Sato I. , Shimada K. , Yokoi A. , Handal J. C. , Asuwa N. , Ishii T.
Published: February 2005

Functional teeth from young American alligators (120 cm to 260 cm total length) were prepared for scanning electron microscopy (SEM) and electron microprobe analysis (EPMA) of the elements of the enamel layer. On the tip of the tooth, the enamel layer is thick, but over the crown it gradually reduces in thickness until it disappears near the cement‐enamel junction. The enamel layer is distinguished by inner and outer layers. The inner layer is formed of separated, irregularly shaped blocks composed of small crystals. In the outer layer, the enamel crystals are closely packed and oriented perpendicularly to the surface. Radially oriented, lamella‐like structures of the enamel are elongated, crystallized bands which extend from the inner to the outer layer of the enamel as reported by Kvam (Acta Odontol. Scand. 17:745–751, 1959). The highest density of crystals occurs in the enamel layer before complete calcification. Concentrations of iron, copper, and fluoride are located approximately 20 μm below the surface of the enamel in the outer layer where crystals are closely packed. The concentration of trace elements (e.g., Fe, F, Cu) is related to the formation of hydroxyapatite.