bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of the sacculus and lagena in a moray eel (Gymnothorax sp.)
Authors: Popper Arthur N. 
Published: February 2005

AbstractThe ultrastructure of the sacculus and lagena of a moray eel, Gymnothorax sp., was investigated using scanning and transmission electron microscopy. Particular emphasis was placed on the orientation of the sensory hair cells and on the ultrastructure of the sensory cells. The ciliary bundles on the sensory hair cells are of several types, each having a different size relationship between the kinocilium and stereocilia. The cell bodies of the sensory cells are similar to the mammalian type II sensory cell. There were no apparent differences in the cell bodies between sensory cells with different ciliary bundles.Hair cell orientation patterns on the saccular and lagenar maculae differ from patterns found in other fishes. The posterior side of the saccular macula in Gymnothorax has cells oriented dorsally and ventrally, as is typical in other non‐ostariophysan species. The anterior end of the saccular macula has alternating groups of anteriorly and posteriorly oriented cells, a situation that differs from the more typical pattern in which anteriorly oriented cells are found on the ventral side of the macula while posteriorly oriented cells cover the dorsal side of the macula. The orientation of cells on the lagena includes ventral cells that are located above a group of dorsally oriented cells. In many other non‐ostariophysans, ventrally oriented cells are generally posterior to the dorsally oriented cells.
A comparative light and electron microscopic study of the pineal complex in the deep‐sea fishes, Cyclothone signata and C. acclinidens
Authors: McNulty John A. 
Published: February 2005

AbstractThe pineal complexes of the two closely related deep‐sea fishes Cyclothone signata and C. acclinidens were compared both qualitatively and quantitatively. Photoreceptor and supportive cells were identified in both species. The deeper‐dwelling species, C. acclinidens, had a significantly greater number of photoreceptor‐cell outer segment saccules and a higher ratio of receptor cells to nerve fibers in the pineal stalk. It was suggested that these indicate increased photosensitivity of the pineal. Supportive cells were sometimes seen to contain arrays of undulating tubules. The functional significance of these tubules is not understood. A prominent dorsal sac is closely associated with the pineal end‐vesicle. Both structures appear to have a common vascular supply suggesting that they are functionally related. Dorsal sac cells contained abundant mitochondria, glycogen, and large filament‐like inclusions.
Cell death and optic fiber penetration in the optic stalk of the chick
Authors: Ulshafer Robert J. , Clavert André 
Published: February 2005

AbstractThe role of dying cells in the optic stalk in relation to retinal fiber migration was investigated in the chick embryo. Cell death was analysed at various stages of development by counting pycnotic nuclei and also by the Gomori acid phosphatase reaction, while nerve fibers were visualised by the Bodian method. A wave of cell death, beginning in the neural retina at stage 18 and advancing with time through the stalk towards the diencephalon, occurred simultaneously or slightly prior to differentiation and migration of ganglion cell axons. Cell death stopped and gliogenesis occurred in the stalk after penetration by retinal fibers. Cell death occurred in the stalk even when fiber penetration was prevented by optic cup ablation. In this case, necrosis ensued until almost complete degeneration of the stalk, usually within three days after the operation, and gliogenesis did not occur. As the stalk degenerated, its cells became heavily pigmented. These observations suggest that the onset of cell death in the optic stalk is determined prior to and independently of retinal fiber penetration. On the other hand, cessation of cell death and subsequent gliogenesis occur only in the presence of ingrowing optic fibers.
Comprehensive schemata on the histology of the liver with consequences in terminology
Authors: Preuss F. , Fricke W. 
Published: February 2005

AbstractNew schemata of the liver are presented to discuss the combination of the three kinds of liver lobules known until today in a chalk‐talk‐manner. Terminology is also discussed. Further investigations are needed involving the construction and the vascular pattern of compound lobules of the three individial lobules of the liver in different species.
The structural organization of the pineal complex in the domestic goose
Authors: Mahon Susan , George John C. 
Published: February 2005

AbstractThe light and electron microscopic structure of the pineal complex of the domestic goose was studied. The complex is tubulofollicular but there is no direct connection between the constituent system of ducts and the third ventricle of the brain. Within the pineal, blood vessels accompanied by sympathetic nerve bundles are confined to the connective tissue. Other nerve fibers and occasional nerve cell bodies, however, do occur among the pineal cells.Three basic pineal cell types were distinguished: (1) elongate epithelial cells which are arranged around follicles and ducts and resemble degenerate photo‐receptor cells; (2) intramural supportive cells which are interspersed with elongate epithelial and intramural supportive cells; and (3) small supportive cells which lie between the bases of the elongate epithelial and intramural supportive cells. The follicular structure, vascularization, presence of secretory granules, and the nature of the elongate epithelial cells indicate that the pineal complex is primarily endocrine though a possible photoreceptive function cannot be ignored. Vesicles, 100‐300 and 40‐100 nm wide, were found within nerves and intramural supportive cells. The larger vesicles, present in pineals collected in the night, probably contain peptidic hormones. The smaller vesicles present in both day and night samples probably contain aminergic hormones.
Nature and cellular origin of the adhesive coats of the lamprey egg (Petromyzon marinus)
Authors: Yorke Marc A. , McMillan Donald B. 
Published: February 2005

AbstractCell surface coats are important in adhesion and other cellular activities. The lamprey egg possesses a surface coat that has been divided into two morphologically and functionally distinct regions. The amorphous apical tuft forms a cap over the animal pole, while the elaborately‐textured adhesive coat covers the ventral two‐thirds of the egg. This latter area is composed of saccules that form rosettes over the egg surface and is derived from the remains of specialized follicular cells which break down during ovulation. The adhesive qualities of these coats may be inhibited or abolished by various proteins and sulphydryl‐blocking agents, thereby implicating, as a possible source of this adhesion, classes of acid and sulphated glycoproteins and glycosaminoglycans which occur on the egg surface.
Structure and formation of ankylosis in Xenopus laevis
Authors: Katow Hideki 
Published: February 2005

AbstractThe structure of ankylotic teeth in Xenopus laevis was studied by light, transmission, and scanning electron microscopy as well as by microradiography in decalcified and undecalcified specimens.The mature teeth of Xenopus laevis are calcified from the crown to the base, fused to the jaw bone, and have no uncalcified area, such as a fibrous ring separating the tooth into the crown and pedicle. Microradiography shows that the mature tooth and jaw bone appear as an X‐ray opaque area, except for the basal region of the dentine. This region is composed of an X‐ray translucent area and an X‐ray opaque thin layer on the lingual side of the translucent area. The mature tooth is composed of two differently calcified areas: (1) a highly calcified area, which makes up almost all of the tooth and contains a thin layer of the basal dentine on the lingual side, and (2) a lowly calcified basal dentine, which is fused to the jaw bone. Therefore, the lowly calcified area does not completely separate the dentine and jaw bone.Repeating banding patterns among the collagen fibrils differ among the dentine‐forming area and the matrices of dentine and jaw bone. During the formation of ankylosis of the tooth germ, collagen bundles in the dentine‐forming area accumulate directly on the surface of the jaw bone. Consequently, the mature teeth of Xenopus laevis fuse to the jaw bone directly without the mediation of the other structures.
Ultrastructure of differentiated malpighian tubules from cockroach nymphs during the molting cycle
Authors: Schmidt Barbara A. 
Published: February 2005

AbstractDifferentiated Malpighian tubules of Periplaneta americana nymphs consist of four distinct regions. The distal, middle, and proximal regions are similar to the same regions in adult tubules. However, the transparent portion of the middle region was found to have ultrastructural characteristics different from those of the longer opaque segment of the middle region and the two other tubule regions. This newly distinguished region is called the lower middle region. Transitional zones, areas where cells show characteristics of two adjacent regions, are apparent between the distal and middle regions and between the middle and lower middle regions.The middle region of primary tubules undergoes an increase in autophagic activity and a modification of its basal infoldings and microvilli shortly before each molt. An increase in autophagic activity is also observed in the lower middle region near the time of molting.
The wrist joint of two‐toed sloths and its relevance to brachiating adaptations in the hominoidea
Authors: Mendel Frank C. 
Published: February 2005

AbstractTwo‐toed sloths have evolved a wrist complex that includes the following traits: (1) diminution and distal migration of the pisiform, with a loss of contact with the ulna; (2) reduction of the distal end of the ulna to a styloid process; and (3) extremely reduced contact between the ulna and triquetrum. These traits were proposed by Lewis ('65, '74) to be indicative of brachiating habits and to be a unique adaptation of the Hominoidea. Cartmill and Milton ('77) recently found a similar complex in the wrists of the lorisines. Very similar adaptations of the wrist among the Hominoidea, lorisines, and two‐toed sloths clearly refute contentions of Lewis and strengthen the hypothesis of Cartmill and Milton that the traits common to those animals are due to similar slow, cautious, but acrobatic locomotion.
Annular bands of lymphoid tissue in the intestine of the mallard duck Anas platyrhynchos
Authors: McGarry Ronald C. , Bourns T. K. R. 
Published: February 2005

AbstractThe annular bands were studied by light and scanning electron microscopy in normal and hormonally bursectomized ducks (Anas platyrhynchos). The four annular bands are normal lymphoid structures of 5–10 mm wide and encircle the intestine at regularly spaced position, two on each side of Meckel's diverticulum. The anterior three are well defined, complete rings whereas the posterior‐most encompasses about one half of the gut circumference. The bands are characterized by prominent follicles in the tunica muscularis, submucosa, and lamina propria. In addition, large numbers of diffusely organized lymphocytes fill the lamina propria and villus cores. Each nodule possesses germinal centre activity, as revealed by the characteristic macrophage content seen in 1.0 μm sections.The bands were present in rudimentary form at hatching. Lymphoid nodules began to develop at day 3 and were morphologically mature at day 98 posthatching. When viewed in the scanning electron microscope, the mucosa of the lymphoid areas was seen to be arranged in tortuous folds, often with irregular fusions. Following hormonal bursectomy, the bands were present, although difficult to detect, and lacked distinct nodules and germinal centres. The mucosal surface still appeared irregularly folded in the SEM, but the folds were more slender with convoluted surfaces.
A scanning electron microscope study of the mesothoracic and metathoracic scolopophorous organs of Lethocerus (Belostomatidae‐heteroptera)
Authors: Anderson Barry R. 
Published: February 2005

AbstractThe presence of scolopophorous organs in aquatic Heteroptera has been reported in a number of species. This study presents a morphological investigation of these sensory structures of Lethocerus (Belostomatidae) as observed with the scanning electron microscope (SEM). Paired mesothoracic and metathoracic organs are present. Externally, each sensory structure consists of a raised sensory membrane. The distal‐most portion consists of thickenings of this sensory membrane (sclerite). The receptor neurons of the mesothoracic organ are of two types—one discolopidial sensillum and 12 monoscolopidial sensilla. The former is attached to the internal wall and distal thickening of the sensory membrane, while the latter are dispersed throughout the interior and attached to the internal wall of the sensory membrane. The structure of the organs suggest that an effective stimulus could be a compression of the membrane. A discussion of possible functions (pressure reception and hearing) is included.
Ultrastructure of the y‐organs of Cancer antennarius in normal and de‐eyestalked crabs
Authors: Hinsch Gertrude W. , Spaziani Eugene , Vensel William H. 
Published: February 2005

AbstractThe paired Y‐organs of crustaceans control the molting process. In males of C. antennarius, these glands are opalescent, lobulated, epithelioid structures embedded in brown fatty tissue. Cells in the periphery extend processes to the connective tissue capsule, an arrangement that suggests increased surface area for metabolic exchange. The processes contain mitochondria and are tipped distally with electron dense material. The cytoplasm, scarce relative to nuclear volume, contains vesicles, polymorphic mitochondria with tubular cristae, and numerous free ribosomes, but little in way of smooth or rough endoplasmic reticulum or Golgi complexes. Progressing from intermolt to the premolt stage, mitochondria, as well as vesicles, and electron‐dense particles in peripheral processes increase somewhat in number. Also, heterochromatin masses concentrate adjacent to the nuclear envelope. Eyestalk removal, which induces premolt stages in some species, did not produce consistent change in Y‐organ substructure in C. antennarius. Although evidence is accumulating that Y‐organs secrete a steroid molting hormone during late intermolt‐premolt, the substructure of the glands exhibits neither (a) striking changes with the molt cycle, nor (b) all the characteristics typical of vertebrate steroid hormone synthesizing glands. Nevertheless, the structural features, respectively, are consistent with biochemical evidence that Y‐organs (a) rapidly take up and convert sterol precursor and secrete a product without its accumulation or change in total sterol pool size, and (b) apparently cannot synthesize the sterol precursor. Y‐organ cytology closely resembles that of some vertebrate steroid hormone secreting glands in which this synthetic capacity is minimal.
Cytodifferentiation and vitellogenesis during oogenesis in arachnida: Cytological studies on developing oocytes of a harvestman
Authors: Kessel R. G. , Beams H. W. 
Published: February 2005

AbstractLight and electron microscope studies were made on harvestman oocytes during the course of their origin, differentiation, and vitellogenesis. The germ cells appear to originate from the ovarian epithelium. They subsequently migrate to the outer surface of the epithelium, where they remain attached often by means of stalk cells which suspend them in the hemocoel during oogenesis. The “Balbiani bodies,” “yolk nuclei,” or “nuage” constitute a prominent feature of young, previtellogenic oocytes, and take the form of large, but variable sizes of electron‐dense cytoplasmic aggregates with small fibrogranular components. The cytoplasmic aggregates fragment and disperse, and cannot be detected in vitellogenic oocytes. The young oocytes become surrounded by a vitelline envelope that appears to represent a secretory product of the oocyte. The previtellogenic oocytes are impermeable to horseradish peroxidase under both in vivo and in vitro conditions. In addition to mitochondria, dictyosomes, and abundant ribosomes, the ooplasm of the previtellogenic oocyte acquires both vesicular and lamellar forms of the rough‐surfaced endoplasmic reticulum. In many areas, a dense homogeneous product appears within the cisternae of the endoplasmic reticulum and represents nascent yolk protein synthesized by the oocyte during early stages of vitellogenesis. Later in vitellogenesis, the oocyte becomes permeable to horseradish peroxidase under both in vivo and in vitro conditions. This change is associated with a massive process of micropinocytosis which is reflected in the presence of large numbers of vesicles of variable form and structure in the cortical ooplasm. Both spherical and tubular vesicles are present, as are coated and uncoated vesicles. Stages in the fusion of the vesicles with each other and with developing yolk platelets are illustrated. In the harvester oocytes, vitellogenesis is a process that involves both autosynthetic and heterosynthetic mechanisms.
Quantitative studies on the skin of the paired species of lampreys, Lampetra fluviatilis (L.) and Lampetra planeri (BLOCH)
Authors: Lethbridge R. C. , Potter I. C. 
Published: February 2005

AbstractThe number of mucous, club, and granular cells in the epidermis, and the number of rows of subcutaneous adipose cells, as well as the thickness of the epidermis and the dermal collagen layer, have been recorded for the larval and metamorphosing stages of the anadromous parasitic lamprey, Lampetra fluviatilis, and for the larval, metamorphosing, and adult stages of the nonparasitic lamprey, Lampetra planeri.In L. fluviatilis, the mucous cells predominated in all stages but were more abundant in fully metamorphosed individuals than in larvae. During metamorphosis, the number of granular cells increased continuously, whereas the club cells showed little change. Although lampreys do not feed during metamorphosis, there was an increase in the thickness of the epidermis and in the dermal collagen sheath; the latter increase probably foreshadows the increase in activity by the adults. Simultaneously, there is a reduction in the subcutaneous fat layer, which can be attributed to mobilization of lipid as an energy source.Changes similar to those just described for L. fluviatilis were also found in metamorphosing L. planeri. However, the pattern altered markedly during adult stages in this nonparasitic species. There were marked declines in the number of cells, in the thickness of the epidermis, in the width of the collagen sheath, and in the quantity of subcutaneous fat.
The morphology of a harpacticoid copepod gut: A review and synthesis
Authors: Sullivan Druscilla Shirley , Bisalputra Thana 
Published: February 2005

AbstractThe digestive tract of a harpacticoid copepod, Tigriopus californicus (Baker), was studied by using techniques of light and electron microscopy. Four cell types could be distinguished: type 1, an embryonic cell which will replace cells worn away or lost during secretion; type 2, a cell which synthesizes and secretes proteins and also plays a role in lipid absorption; and types 3 and 4, two cell types which absorb lipids. From the abundance of each cell type, the length of microvilli, the development of basal plasma membrane (PM), and luminal projections, the following conclusions were made. (1) The midgut caecum absorbs digested nutrients. (2) The anterior midgut absorbs nutrients and more importantly functions in merocrine and exocrine secretion. The presence of concretions in cell types 2 and 3 in the anterior midgut suggests that these tissues contribute in excretion, and in water and/or ion regulation. (3) The posterior midgut absorbs nutrients and contributes some holocrine secretion.
Sense organs on the antennal flagellum of the human louse, Pediculus humanus (Anoplura)
Authors: Slifer Eleanor H. , Sekhon Sant S. 
Published: February 2005

AbstractTactile hairs are present on all three subsegments of the antennal flagellum of the human louse. There is, in addition, a single chemoreceptor (tuft organ) on subsegment 2 and 12 or 13 chemoreceptors (one tuft organ, two pore organs and nine or ten pegs) on subsegment 3. The cuticle surrounding the bases of the pegs at the tip of the antenna is unusual in that parts of it are perforated by many fine pores. This cuticle is underlain by a thin layer of dendrites. This region may also have a chemoreceptor function.
Light and electron microscopic studies of crayfish hemocytes
Authors: Sternshein David Jules , Burton Paul R. 
Published: February 2005

AbstractUsing light and electron microscopy, three hemocyte types are described in the hemolymph of the crayfish. The coagulocyte comprises 65% of the total hemocyte number and contains medium‐sized cytoplasmic granules, abundant dilated rough endoplasmic reticulum, and a highly developed Golgi complex. It rapidly undergoes cytolysis in vitro and participates in coagulation by releasing the contents of its granules to the hemolymph. The granulocyte comprises 31% of the total hemocyte number and is capable of phagocytosis. It contains large, irregularly shaped cytoplasmic granules, a moderately developed Golgi complex, and moderate amounts of non‐dilated rough endoplasmic reticulum. During coagulation in vitro, the cell attaches and spreads onto the substratum; this is followed by a slow intracellular granule breakdown and cytolysis. The amebocyte comprises 4% of the total hemocyte number and it is also capable of phagocytosis. It possesses small cytoplasmic granules, many vacuoles, a moderately developed Golgi complex, and large amounts of smooth endoplasmic reticulum. It is distinguished from the other two cell types by being stable and motile in vitro.
Morphometrics of the skeleton of Dermophis mexicanus (Amphibia: Gymnophiona). Part I. The vertebrae, with comparisons to other species
Authors: Wake Marvalee H. 
Published: February 2005

AbstractMorphometric analysis of vertebral structure in caecilians (Amphibia: Gymnophiona) is presented. Ontogenetic variation in Dermophis mexicanus is analyzed through the 100+ vertebrae composing the column. Vertebral structure in adult D. mexicanus is compared with that in Ichthyophis glutinosus and Typhlonectes compressicauda. Centra of the atlas, second, tenth, 20th, and 50th vertebrae grow at allometrically different rates in D. mexicanus, though the 20th and 50th are not significantly different, Growth appears significantly slower in several dimensions of anterior and posterior vertebrae relative to midtrunk vertebrae in all three species. Mensural patterns throughout the entire column are similar in the terrestrial burrowers D. mexicanus and I. glutinosus; patterns in the aquatic T. compressicauda differ substantially from those of the burrowing species and are strongly influenced by allometry. Of the 112 D. mexicanus examined, 13.4% had vertebral anomalies, usually fusions.