bluuebunny/crossref_metadata_2025_split huggingface dataset:
Histology of the neurosecretory system and the retrocerebral endocrine glands of the adult migratory grasshopper, Melanoplus sanguinipes (Fab.) (Orthoptera: Acrididae)
Authors: Dogra C. S. , Ewen Al B. 
Published: February 2005

AbstractNeurosecretory cells of only one type (A, sub type A2) are seen in adult Melanoplus. Two groups of about 400 cells each are located dorsally in the pars intercerebralis medialis; four cells are located deep within the protocerebrum. We found no neurosecretory cells in other parts of the central or sympathetic nervous systems. In about 10% of the specimens, there was marked asymmetry in the location of the dorsal cell groups, with both of these groups and their axons located in one lobe of the protocerebrum.The nervi corporis cardiaci 1 cross‐over in the corpus cardiacum, with the result that material produced by neurosecretory cells on one side of the brain is transported along axons that undergo two chiasmata to the corpus cardiacum of the same side.Stainable secretory material could be traced clearly from the cerebral cells to the corpus cardiacum, and even into the oesophageal nerves from the hypocerebral ganglion. However, stainable neurosecretory material is never present in the corpus allatum or along any of the nerves to this gland.
The cytology of the vitellogenic stages of oogenesis in Drosophila melanogaster. II. Ultrastructural investigations on the origin of protein yolk spheres
Authors: Cummings M. R. , King R. C. 
Published: February 2005

AbstractThe cytology of the vitellogenic stages in the development of the oocyte of Drosophila melanogaster is described following an electron microscopic study of sections of plastic‐embedded ovaries and single egg chambers. One of the first morphological manifestations of yolk deposition is an infolding of the plasma membrane of the oocyte and the abscission of membranous tubules and vesicles. The protein (alpha) yolk spheres originate along the oocyte periphery from membranous sacs to which are attached membranous tubules. It is assumed that the majority of the protein within the alpha sphere is synthesized by neighboring tubular, rough surfaced endoplasmic reticulum. The other organelles in the ooplasm are described, and their origin and possible roles in vitellogenesis are examined. The relative importance of intra‐ and extra‐ovarian synthesis of yolk protein in different insect species is discussed.
Evidence for the fusion of myoblasts in amphibian embryos. II. Xenoplastic transplantations of somitic cells from anuran to urodele embryos
Authors: Loeffler Clarence A. 
Published: February 2005

AbstractIn order to further support the thesis that myoblast fusions lead to the formation of multinucleate myotubes during early amphibian development, prospective myoblasts from frog embryos (Rana pipiens; Xenopus laevis) were orthotopically and heterotopically transplanted into embryonic salamanders (Ambystoma maculatum; A. tigrinum). The stages employed ranged from gastrula to early tail bud. After the hosts had developed to more advanced stages, they were fixed, sectioned in the frontal plane, and prepared for histological observation. Of special interest in these xenoplastic combinations are the nuclear and cytoplasmic differences between anuran and urodele embryonic cells.In most cases, transplanted cells tended to form a tissue complex distinct from the host tissues. This naturally decreased the opportunity for cell intermingling and consequently reduced the chances for fusions between graft and host myoblasts. Thus, there was a correlation between the extent of dispersion of the transplanted cells and the frequency of chimeric myotubes. Nevertheless, in each experimental series, a number of multinucleate myotubes emerged consisting of nuclear and cytoplasmic components of both graft and host cells. These chimeric myotubes, which must have originated by multiple cell fusions of anuran and urodele cells, (1) retained their distinct nuclear differences, (2) displayed resorption of both anuran and urodele yolk platelets, and (3) contained cross‐striated myofibrils. The function of these chimeric cells, their synthesis of myofibrils, and the apparent lack of free intermingling at the cellular level, are discussed.
Tooth replacement patterns in young Caiman sclerops
Authors: Miller William A. , Radnor Carolyn J. P. 
Published: February 2005

AbstractAlthough there are many reports of tooth replacement patterns in lower vertebrates, few show the range of pattern to be found in a number of similar aged specimens of one species. Fifteen specimens of Caiman sclerops, head length 4–5 cms, were examined by a radiographic technique and their tooth replacement patterns analysed. Whole head radiography and dissected head radiographs were compared and the resulting tooth replacement waves were found to be comparable. Wave replacement (sensu Edmund, '60) in odd and even tooth positions in the tooth row was observed in all the specimens examined. Whereas most waves passed in a cephalad direction, wave reversal (caudad) was also observed, particularly in the anterior parts of the jaws. In some specimens simple alternation in tooth replacement was observed, particularly in the mid‐portion of each quadrant. The smooth, age‐related change‐over from cephalad to caudad demonstrated by Edmund ('62) in captive Alligator mississippiensis was not observed in wild specimens of Caiman sclerops.
Neurosecretion in the scorpion Heterometrus swammerdami
Authors: Habibulla Mohammad 
Published: February 2005

AbstractGross morphology, staining characteristics and mapping of the diversity of the neurosecretory cell types in the brain and subesophageal ganglion of the scorpion Heterometrus swammerdami are reported. Special neurosecretory cell groups whose product is stainable with orange‐G, acid fuchsin and Heidenhain's hematoxylin are present in the brain.In many of the living isolated neurosecretory cells, the secretory material appears luminous when viewed with dark ground illumination and granular when observed with phase contrast microscope.In the subesophageal ganglion the metameric arrangement of neurosecretory cells is distinct. Neurosecretory product accumulating in specific regions of subesophageal ganglion, and its axonal transport into the dorsal nerves and their termination in cephalic blood vessels apparently representing a storage and release organ of neurosecretion is reported.
A light and electron microscopic study of the heart of a crayfish, Procambarus clarkii (giraud). I. histology and histochemistry
Authors: Howse Harold D. , Ferrans Victor J. , Hibbs Richard G. 
Published: February 2005

AbstractThe adventitia of the crayfish heart consists of about five layers of uninucleated cells that often contain large amounts of glycogen. The outer and inner boundaries of the adventitia are represented by amorphous, homogeneous layers that are rich in neutral and acidic carbohydrates.The myocardium has a trabeculated appearance, due to the branching and anastomosing of the muscle cells. Studies on the localization of various oxidative enzymes show that the mitochondria are contained principally in the cell periphery and the myofibrils in the cell core. Intercalated discs appear as dark, irregular lines that traverse the muscle cell at a level that corresponds to that of a Z band. The myocardial cells branch and radiate from loci that are formed either by a single stellate cell or by the common end‐to‐end junctions (intercalated discs) of several cells. The function of these loci is discussed.The local cardiac nervous system consists of a Y‐shaped ganglionic trunk that contains eight large anterior and eight small posterior nerve cells.
Ultrastructural aspects of cat submandibular glands
Authors: Shackleford John M. , Wilborn Walter H. 
Published: February 2005

AbstractSubmandibular glands of five adult female cats were examined by conventional electron microscopic techniques. All gland acini are mucous secreting and each acinus is capped with mucous secreting demilunar cells. Secretory product of demilunar cells is more electron lucent than that of acinar cells. The demilunes show intercellular tissue spaces and intercellular canaliculi whereas similar specializations are absent between acinar cells. Mitochondria and arrays of granular endoplasmic reticulum are more numerous in demilunar cells than in acinar cells. In acinar and demilunar cells secretory droplets first appear as enlarged Golgi saccules which subsequently become closely related to cisternae of the granular endoplasmic reticulum. Filamentous structures, interpreted as mucin molecules, are present in secretory droplets of acinar cells. Intercalated ducts are short, consisting of several junctional cells between acini and striated ducts. Striated ducts are long and tortuous and contain light cells, dark cells and basal cells. Light cells contain numerous membrane bound granules in their distal ends whereas dark cells show electron lucent vesicles in the same position. Basal cells contain a paucity of organelles and membrane plications but exhibit hemidesmosomes along their basal plasma membranes. Myoepithelial cells are abundant in relation to acinar and demilunar cells. Nerve terminals are present in some instances between acinar cells or between acinar and myoepithelial cells.
Genesis of the reproductive system of mosquitoes II. Male of Aedes stimulans (walker)
Authors: Horsfall William R. , Ronquillo Maria C. 
Published: February 2005

AbstractThe imaginal male of mosquitoes bears a combination of organs and appendages that make it morphologically distinctive. Its reproductive organs produce sperm cells, convey and extrude them, provide accessory fluids, and insure copulation and insemination. In Aedes stimulans (Walker) these organs are derived from one of the two sets of primordia provided by the embryo. The second set of primordia is capable of producing the feminine reproductive system under unusual circumstances.Testes are derived from two compact ovoid masses of cells suspended in the hemocoel of abdominal segment 6. Each enlarges slowly throughout larval instars 1–3 and elongates very rapidly late in instar 4. Specialization of the cellular mass into sperm cells proceeds forward from the caudal end early in pupal life. From the beginning, a sheath of nutritive cells or fatbody encases each gonad, and no tracheation of the mass is evident although one small trachea sends branches to the encasing fatbody late in larval life.The efferent canal from each testis is derived from a tenuous filament extending caudally from each gonad to the venter of segment 9 and a small cluster of cells in the wall of the hemocoel on the ental surface of imaginal disc 9. Early in pupal life the filaments become the tubular vasa efferentia. The caudal clusters are primordial terminal parts of the lateral tract that become vasa deferentia, seminal vesicles and associated accessory glands. The ejaculatory canal comes from a short pouch derived from the median genital plate of disc 9.All external parts except the paraprocts are products of disc 9. The bilateral buds begin to proliferate in larval instar 4 and become the basistyles, dististyles and claspettes of the gonapophyses during pupal life. The phallosome is derived from the median genital plate.Primordia of a possible feminine reproductive system and cerci remain undifferentiated and disappear early in pupal life in the normal course of events. Primordia that were recognizable include those of ovaries, parts of lateral oviducts, median genital tract and cerci.
Oögenesis of the freshwater turbellarian Hydrolimax grisea (Platyhelminthes; Plagiostomidae) with special reference to the history of the supernumerary asters and central bodies
Authors: Donald W. Donald 
Published: February 2005

AbstractThe oöcyte of H. grisea is surrounded early in its growth by the accessory cell. A yolk halo, secreted by accessory parenchymal cells, subsequently envelops the oöcyte and its accessory cell. Of particular interest are the supernumerary asters, and their central bodies, which surround the oöcyte nucleus. The asters are exceptional because they appear in unfertilized oöcytes with (apparently) intact germinal vesicle membranes. Coincident with sperm penetration the supernumerary asters grow. Their rays elongate and thicken. The nuclear membrane disappears. The supernumerary asters aggregate and disappear prior to the maturation (meiotic) divisions. The maturation asters from with distinct centrioles and centropheres while the egg is still within the parenchyma of the worm. Their formation is independent of sperm penetration. The polar bodies are given off within the cocoon.
Morphogenesis of albino rat lung: An autoradiographic analysis of the embryological origin of the type I and II pulmonary epithelial cells
Authors: O'Hare Karen Hitchcock , Townes Philip L. 
Published: February 2005

AbstractA correlation of autoradiographic and histochemical data indicates that the type I and II pulmonary epithelial cells are endodermally‐derived; and, that the interstitial pulmonary cells are mesodermally‐derived. Tritiated thymidine (T‐H3) was found to be an excellent cell marker for in vivo developmental studies of mammalian (rat) lung. At a dose of 3 μc per gm (specific activity, 15.6–16.9 c per mM) maternal body weight, T‐H3 crosses the placenta in amounts sufficient to effect heavy labeling of dividing cells. A partial placental barrier to T‐H3 was found in late stages of development. Following an injection of T‐H3 on day 16 of gestation, a higher rate of endodermal cell division was reflected by higher labeling indices and a steeper slope of the endodermal dilution curve as opposed to the mesoderm. This differential in labeling was maintained through the third postnatal day. Neonatal labeling patterns of the definitive cell types (type I and II pulmonary epithelial cells, interstitial pulmonary cells) reflected those of their germ layer precursors.Histochemical analysis of the developing rat lung demonstrated large accumulations of cytoplasmic glycogen in areas of rapid cell division (endodermal cells). As the mitotic rate decreased and cellular differentiation progressed, glycogen decreased; postnatally it is not a feature of mature pulmonary cell types.
Ultrastructural studies on the corpora cardiaca‐allata complex of the adult alfalfa weevil, Hypera postica
Authors: Tombes Averett S. , Smith David S. 
Published: February 2005

AbstractThe organization of the corpora cardiaca and corpora allata of the female alfalfa weevil, Hypera postica, generally parallels that reported for other insects with extrinsic neurosecretory axons, intrinsic neurosecretory cells, and interstitial or glial cells appearing in both glands.Connecting the brain with the cardiacum are the extrinsic neurosecretory axons containing granules between 600 and 2200 Å. Granules with a diameter of up to 4000 Å are found in the intrinsic secretory cells of the corpus cardiacum.From the lobed corpus cardiacum, axons extend along a short nerve trunk into the ovoid corpus allatum. A characteristic of this gland is the presence of a layer of axons, ensheathing most of the corpus allatum and situated beneath an external basement membrane. These axons are believed to have their origin in the protocerebral neurosecretory cells. Although the c. allatum is known to be engaged in the release of hormonally active material, the cytoplasmic organization does not strongly reflect such activity.The glands of the diapausing weevil appear similar to those of the active weevil with a reduction in cytoplasm and a consequent folding of the plasma membrane.
External prostate of the hedgehog
Authors: Hruban Z. , Martan J. , Mochizuki Y. 
Published: February 2005

AbstractThe external prostate of male hedgehogs (Erinaceus europeus, Hemiechinus sp.) was studied at the beginning and at the end of the breeding seasons. Its tubular secretory units contain two types of epithelia, columnar and stratified. The columnar epithelium has abundant rough endoplasmic reticulum and forms secretory granules. The stratified epithelium undergoes cellular changes culminating in appearance of nuclear and cytoplasmic inclusions, nuclear pyknosis and desquamation of cells and nuclei into lumen. The nuclear inclusions contain protein and abundant silver‐reducing substances. These inclusions may be derived from the residual protein of the nucleus.
Structure of the ellipsoid sheath in the spleen of the armadillo (Dasypus novemcinctus). A light and electron microscopic study
Authors: Hayes Thomas G. 
Published: February 2005

AbstractThe spleen of the armadillo is invested by a capsule composed predominantly of smooth muscle. Inward extensions from the capsule contribute to an extensive system of trabeculae of the non‐vascular type. The white pulp presents a typical follicular arrangement and the red pulp is permeated by an anastomosing series of venous sinsuses. The capillary segment of the penicillar artery is invested by an ellipsoid sheath. The spleen of the armadillo may be included in the class of mammalian spleens characterized as sinusal in nature and possessing ellipsoid sheaths. Electron micrographs of thin sections of the sheathed capillaries demonstrate a high‐type of endothelium. A characteristic feature of this endothelium is the presence of a distinct intracytoplasmic fibrous component.The reticular cells comprising the sheath proper exhibit various sized vacuoles and inclusion bodies suggestive of their potentially phagocytic nature. In both light and electron microscopy, venous sinuses lie in close proximity to the peripheral cells of the ellipsoid sheaths. Within the wall of the venous sinuses, patent openings are appearent between the lining cells. If such an arrangement exists in the functional state of the organ, it could provide for an additional means of exposure of both plasma and cellular elements to the adjacent phagocytic cells of the sheath proper.
The finestructure of nerve branches and neuromuscular junctions in the coxal adductor of the cockroach, Gromphadorhina portentosa
Authors: Faeder Isabelle R. , Salpeter Miriam M. 
Published: February 2005

AbstractThe neuromuscular junctions of a fast coxal adductor of Gromphadorhina portentosa show great variability in both axon terminal diameter and extent of post‐junctional sarcoplasmic specializaton. Finestructural equivalents of both cone and brush type nerve endings are present. The large motor axons innervating this muscle are surrounded by a pervasive lemnoblast sheath, leaving the axon surface exposed only in the area of synaptic contact. Connective tissue covers the nerve and fills the spaces between sheath cell processes in the nerve trunk, but is lost after it enters the muscle. The role of sheath cells in nerve function is discussed in the light of these findings.
Extirpation experiments on embryonic rudiments of the carapace of Chelydra serpentina
Authors: Yntema C. L. 
Published: February 2005

AbstractSomites, along with adjacent neural tube and overlying ectoderm, were extirpated unilaterally from embryos of Chelydra serpentina. Mesoderm of three somites was removed from various levels. The operations included the last formed somite and were done on embryos with 12 to 22 pairs of somites. In practice it was found that ventromedial portions of the somites were not included in the extirpation. The animals were preserved before pigmentation became heavy. The cartilaginous skeleton was stained selectively.The extirpations resulted in depletions of ribs consonant with relating the second rib to the fourteenth somite. The somites behaved as mosaics; they did not reconstitute each other nor did they regenerate after partial extirpation. The rudiments for the ribs were separable from the rudiments of the vertebrae, the sclerotomes, and were found to arise from a more lateral portion of the somite.The scutes are ectodermal derivatives, which are held to be dependent upon underlying somitic mesoderm for their differentiation. The extirpations resulted in abnormalities and depletions of scutes.
Studies on aggregation of embryonic cells: Initial cell adhesions and the formation of intercellular junctions
Authors: Sheffield Joel B. 
Published: February 2005

AbstractThe aggregation in vitro of embryonic neural retina cells was studied by electron microscopy with special emphasis on the reformation of intercellular junctions. The results show that (1) embryonic neural retina cells dissociated with trypsin retain morphological characteristics and polarity after dispersion into a suspension; (2) initial adhesions between the aggregating cells are nonspecific with respect to cell type and to the site of cell surface involved; (3) histogenetic associations in clusters of reaggregated cells appear within two hours after the start of aggregation. A hypothesis is presented that coated vesicles play a role in the formation of intercellular junctions.
The segmentation of the gnathobdellid leeches with special reference to the indian leech Hirudinaria and medicinal leech Hirudo
Authors: Bhatia M. L. 
Published: February 2005

AbstractLarge number of annuli in Hirudinea are not true segments, and in the absence of spacious bodycavity and septa in adult no decision was taken regarding limit of a somite, until Gratiolet 1862 recognised a segment by colour marking, repetition of nephridial openings, and especially by the presence of segmental receptors, distinguishing first annulus of a segment. Whitman 1884 gave precision to these determinations and analyzed morphology of leeches to logical completeness. He recognised that though Hirudinaria and Hirudo have 102 body annuli and posterior sucker, true segments are only 26 plus 7.Castle ('00) and Moore ('00) proposed a new scheme of segmentation, with segmental receptor bearing annulus, as central annulus of a complete somite, with nerve ganglion, like that of other annelids, in center of a segment. They orientated everything roundabout the ganglion without noticing distorted fate of organ system.In this paper both the views are compared. Morphological and embryological studies reveal that the annulus bearing the segmental receptors in uniformly first annulus of all segments, including incomplete segments at the two extremities, with nerve ganglion in first annulus of the segment.Clitellum occupies three natural segments, IX, X, XI; crop caeca, nephridia, testis sacs, haemocoelomic channels and “rhomboidal figures” formed by ventrolaterals, all make a complete unit, well integrated in such segment. Conclusive evidence comes from the presence of septa at the level of each nerve ganglion in embryos of Hirudinaria. These observations corroborate Gratiolet and Whitman's view.