bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural features of cardiac muscle cells in a tarantula spider
Authors: Sherman R. G. 
Published: February 2005

AbstractThe ultrastructural features of cardiac muscle cells and their innervation were examined in the tarantula spider Eurypelma marxi Simon. The cells are transversely striated and have an A band length of about three microns. H zones are indistinct and M lines are absent. Thick and thin myofilament diameters are approximately 200 and 70 Å respectively. Eight to 12 thin filaments usually surround each thick one. Accumulations of thick and thin myofilaments occur perpendicular to the bulk of the myofilaments in some cells. The Z line is discontinuous and thick filaments may pass through the spaces in the Z line. Extensive systems of sarcoplasmic reticulum and transverse tubules are present; these form numerous dyadic junctions in both A and I band regions. Sarcolemmal invaginations form Z line tubules; lateral extensions of the plasma membrane portion of these invaginations form dyads. Nerve branches of the cardiac ganglion make multiple neuromuscular synapses with at least some of the cardiac muscle cells. Both large granular and small agranular vesicles are present in the presynaptic terminals. Intercalated discs similar to those present in other arthropod hearts occur between the ends of adjacent cardiac muscle cells.
Cytophysiological basis of disruptive pigmentary patterns in the leopard frog Rana pipiens. I chromatophore densities and cytophysiology
Authors: Smith‐Gill Sandra J. 
Published: February 2005

AbstractStatistical analyses of chromatophore densities and morphological states in wild type, burnsi, and kandiyohi: adult Rana pipiens integument yielded the conclusion that disruptive pigmentary pattern is permanently defined by regional chromatophore densities. Spatial chromatophore patterning is enhanced and rendered more visible by the morphological and physiological differences among chromatophores within the various pattern regions. Specifically, (1) chromatophores were differentialy distributed among pattern regions, (2) greater complexity of gross disruptive patterning had greater underlying melanophores densities, (3) there were significant density differences among non‐sib individual animals, among fertilization, and among shipment batches, but not among full‐sibs, and (4)kandiyohi individuals had more while burnsi individuals had fewer total melanophores than wild type. A stellate morphology was significantly correlated with high melanophore density, although the relationship of melanophore density to melanophore morphology differed among pattern regions and among genotypes. The functional interrelationships of density and morphology, and their role in disruptive patterning and coloration, are discussed.
Ultrastructural analysis of the functional copulatory organ of the male rotifer, Asplanchna brightwelli
Authors: Aloia Roland C. , Moretti Richard L. 
Published: February 2005

AbstractThe male rotifer copulatory organ is composed of a urethral canal extending from the tip of the copulatory organ internally to a layer of microvilli. The microvilli project from two different cell types, referred to as the internal and peripheral microvillar cells according to their location. At this microvillar junction a second canal, the vas deferens, continues posteriorly and enters the sperm duct region of the testis. The channel of the vas deferens is formed from the inner wall of three separate cells; the cap, intermediate and basal cells. Peripheral to these cells and parallel to them for their entire length, cross sections of seven prostate gland cells can be observed. Anteriorly, these gland cells are connected to the basal end of the microvillar layer via a short neck region, through which glandular secretion occurs only during copulation. The mechanism of secretion appears to be a form of exocytosis whereby the secretory granule membrane fuses with the cell plasmalemma so that rupturing at the point of fusion will release the granule content into the neck region.The prostate gland cells contain an abundance of autophagic vacuoles while most of the other cells of the copulatory organ contain primary lysosomes and cytolosomes. These organelles may be associated with the aging process in rotifers, or, as in the case of the prostate gland‐autophagic vacuoles, with a fast organelle turnover during secretion.
Tooth replacement in the bowfin (Amia calva — Holostei)
Authors: Miller William A. , Radnor Carolyn J. P. 
Published: February 2005

AbstractThe dissected tooth bearing bones of 20 specimens of Amia calva (Pisces:Holostei) ranging from the third to tenth season have been examined radiographically and in alizarin red S stained and cleared specimens. Although forms of alternate (1:1) tooth series replacement (sensu Edmund, '60) were frequently observed, even in the youngest, immature specimens, many examples of irregular replacement were recorded. In several bones, the maxillae in particular, series with every third (2:1) or fourth (3:1) tooth replacing were seen and possible patterns of 2:2, were recorded. It is concluded that these data are not consistent with the Zahnreihen concept but support a morphogenic field concept of tooth development.
Superficial venous arrangement of the face and neck of the tufted capuchin, Cebus apella linnaeus, 1758
Authors: Madeira Miguel C. , Watanabe Ii‐Sei 
Published: February 2005

AbstractThe description of the superficial veins of the face and neck was based upon the dissection of 28 male and female adult tufted or brown capuchin monkeys (Cebus apella), captured in southern Goiás, Brazil.Although the venous arrangement of these areas is basically the same in all primates, some characteristic differences were noted: 1. the anterior jugular and common facial veins were absent; 2. most specimens had a venous hyoid arch, and a connecting vessel between the external jugular and subclavian veins; 3. the inferior petrosal sinus drains into the external jugular v. through the postglenoid foramen; 4. the facial, lingual and cephalic veins open into the external jugular vein; 5. both the internal and external jugular veins have about the same diameter; 6. the vascular pattern appears to be quite stable; anatomical variations appear to be few and unimportant.
Development of electric organs of Gymnarchus niloticus (Fam. Gymnarchidae). II. Formation of spindle
Authors: Srivastava C. B. L. , Szabo T. 
Published: February 2005

AbstractThe development of electric organ spindles of Gymnarchus niloticus has been investigated with respect to the exact time and place of origin and the process of formation of the adult plan. The results are compared with those of Dahlgren ('14). A common primordium for all the electroplates of of a spindle as held by Dahlgren ('14) is not supported by the present work.
The chicken trigeminal ganglion II. Fine structure of the neurons during development,
Authors: Gaik Geraldine C. , Farbman Albert I. 
Published: February 2005

AbstractA morphological study of the developing chick trigeminal ganglion was done. For descriptive convenience, four stages of development have been defined: Phase I (2 to 4 days of incubation) — Both the neural crest and epidermal placode contribute to the forming trigeminal ganglion, which is comprised of clusters of undifferentiated cells and primitive neuroblasts. Toward the end of this phase, satellite cells and unmyelinated nerve fibers are seen. Phase II (5 to 10 days of incubation) — In the lateral portion of the ganglion, large differentiating neuroblasts and young bipolar and pseudounipolar neurons were present. The latter were characterized by a large, eccentrically located nucleus at one pole, a long axonal process at the opposite pole, and a clear centrosphere region between the two. In the medial region of the ganglion, most of the neurons were smaller and more closely packed together. Phase III (11 to 17 days of incubation) — The ganglion was constituted of bipolar and pseudounipolar cells with an apparently random distribution of small and large neurons. Nissl bodies appeared in developing neurons. Phase IV (18 days of incubation to 3 weeks post‐hatching) — Light and dark neurons first made their appearance. Dark neurons were characterized by (1) clear perinuclear cytoplasm containing a Golgi apparatus, vesicles and mitochondria and (2) a peripheral cytoplasm of densely packed stacks of Nissl substance. Light neurons contained individual clumps of Nissl substance distributed in a pale cytoplasmic matrix.
Morphological and physiological studies of the silkmoth ovary I. The general histology and some histochemical properties of the ovary of Samia Cynthia (Drury)
Authors: White Joan F. , Larsen Joseph R. 
Published: February 2005

AbstractOvaries of the giant silkmoth Samia cynthia Drury have been studied histologically and histochemically during diapause, adult development, and after injury to the diapause animal. In addition to cellular changes involved in follicular growth and vitellogenesis, changes in the intermediate layer cells are very striking, showing a distinct pattern during ovarian development and after injury. Two types of granules, one periodic acid‐Schiff (PAS) positive, the other paraldehyde‐fuchsin (PF) positive, change in their number and distribution in the intermediate cells during development and after injury. The PAS‐positive granules appear during the first one‐third of development, increase in number and size until the tenth day, then gradually dwindle in number and size, and disappear in the adult cells. The PF‐positive granules, present in moderate numbers in the diapause animal, decrease in number until the tenth day of adult development, then reappear, and are present again in adult intermediate cells. After injury to a diapause pupa, intermediate cells show a greatly increased number of PF‐positive granules, but none that are PAS‐positive.The PAS‐positive granules are a neutral or mildly acidic mucosubstance, and may correspond to lysosomal activity, while the PF‐positive granules may be a neurosecretory‐like substance or the product of hormone‐dependent protein synthesis, since the patterns of granule distribution in the intermediate cells seem to reflect both general metabolic and hormone‐related events.
Gross and microscopic morphology of the Glandula proctodealis (foam gland) of Coturnix c. japonica (Aves)
Authors: Klemm Robert D. , Knight Carl E. , Stein Sherryl 
Published: February 2005

AbstractThe dorsal proctodeal wall of the Coturnix contains a gland which is especially well‐developed in the sexually active male and which secretes a foamy exudate. This gland has not been recorded in any other genus of birds and appears to be unique to members of the genus Coturnix. On the basis of its location in the adult we have named this gland the proctodeal gland (glandula proctodealis). Structure of the gland does not conform to any curently defined category of glands because it is an aggregate of individual glandular units each of which opens independently into the proctodeal cavity but with the entire structure enclosed by a connective tissue capsule. We have thus characterized it as an aggregate gland. Observations on the arrangement and composition of the fibrous capsule and its intimate relationship to the perimysium of M. sphincter cloacae indicate that release of the secretion probably results from contraction of the cloacal musculature. Preliminary data suggest that development of glandular tissue in the female may be a function of age rather than of androgen sensitivity which characterizes the male gland. It is concluded that the chemical nature of the glandular secretion and its function in the sexually active bird, as based on presently available information, remains unknown.
Cutaneous wound healing in the sea cucumber, Thyone briareus
Authors: Menton David N. , Eisen Arthur Z. 
Published: February 2005

AbstractWound healing in the integument of the sea cucumber, Thyone briareus, was studied for up to 50 days after inflicting wide excisional wounds and for 14 days after producing incisional wounds. Rapid re‐epithelialization of the wound was effected by the migration of epidermal cells and pigment cells from the periphery of the wound margin. This occurred without apparent evidence of concomitant mitotic activity. Dermal wound healing was completed by the fourteenth day in the incision wounds but occurred very slowly in the broad excision wounds. Morula cells seem to be involved in both epidermal and dermal wound healing, although their precise role is unknown. In excisional wounds the integument was never completely restored to its normal appearance during 50 days of observation.
Ultrastructural characteristics and innervation of the pineal organ of the antarctic seal Leptonychotes weddelli
Authors: Cuello Augusto Claudio 
Published: February 2005

AbstractThe electron microscopy of the epiphysis cerebri of the antarctic seal Leptonychotes weddelli revealed a highly organized organ. The general cytological characteristics of the pinealocytes and the glial cells are described. The capillary blood vessels are the nonfenestrated type. The organ is richly innervated by mainly unmyelinated nerve fibers. Most of the axons end in the inner part of the organ, around vessels, some of them in relation with pinealocytes. The significance of the findings is discussed.
Early development of the kelp fly, Coelopa frigida (Diptera). II. Morphology of cleavage and blastoderm formation
Authors: Schwalm Fritz E. , Bender Harvey A. 
Published: February 2005

AbstractCleavage and blastoderm formation in Coelopa frigida are extremely rapid developmental processes. In short (6–7 minutes) successive cell cycles, nuclei multiply and spread out through the egg. The movement seems to be aided by endoplasmic vesicles and cisternae which are in direct contact with the nuclear membrane. The first cells to separate from the egg plasmodium in early superficial cleavage stages are the pole cells.Precursor material from multivesicular bodies forms the pole cell membranes. The primary nuclei from the posterior pole region are removed from the blastoderm by the pole cell segregation. Blastoderm nuclei from the regions adjacent to the posterior pole migrate into the residual periplasm after pole cell segregation has been completed and constitute the blastoderm nuclei in that region of the egg. Nucleoli are not revealed during internal cleavage. They appear in pole cells shortly after their segregation. The generation time of the blastoderm nuclei increases after the twelfth cleavage. Concurrently, nucleoli form in the blastoderm nuclei and permanent cell membranes separate individual blastoderm cells. After blastoderm cells have been separated from each other, they remain in contact with the interior yolk sac by means of cytoplasmic canals. This contact is maintained at least during the early phases of blastokinesis. Observations on nuclear migration and rapid membrane formation are discussed as examples of protein assembly from subunits as an alternative to de novo protein synthesis in early stages of development.
Scanning and transmission electron microscopic studies of jejunal microvilli of the rat, hamster and dog, ,
Authors: Anderson James H. , Taylor A. B. 
Published: February 2005

AbstractScanning and transmission electron microscopy were used to investigate the surface area and number per unit area of microvilli from jejunal villus epithelial cells in the rat, hamster and dog.The calculated mean microvillus surface area was 0.419 μ2, 0.573 μ2, 0.751 μ2 for the rat, hamster and dog respectively.The largest number of microvilli per square micron freeze dried villus surface was measured in the rat with a mean value of 65. Hamster and dog freeze dried specimens had lower mean values of 54 and 34 microvilli respectively.The total microvilli surface area in square micron per square micron villus surface was more closely related for the three species with values of 27.23 for the rat, 30.94 for the hamster and 25.53 for the dog.These data indicate an inverse relationship between the mean microvillus surface area and population density in the species studied. However, the total microvilli surface area per unit villus surface is relatively similar for the three species.The observed number of microvilli per unit villus surface was shown to vary depending upon the dehydration technique employed for preparation of scanning electron microscopic specimens. This variation probably reflects shrinkage artifact and should be considered in soft tissue studies involving the scanning electron microscope.
Developmental aspects of sirenomelia in the mouse
Authors: Schreiner Ceinwen A. , Hoornbeek Frank K. 
Published: February 2005

AbstractThe mutant gene srn produces sireniform abnormalities in the mouse. The effects of this gene on normal prenatal development were examined histologically by retrograde analysis from day 10 through day 18 of gestation.The sireniformphenotype is characterized by the fusion of the hindlimbs and accompanying defects of the posterior appendicular skeleton. Visceral defects involve the urogenital system and the lower intestinal tract. A single umbilical artery arises from the dorsal aorta and controls the fetal circulatory pathway normally mediated by the lateral umbilical arteries. This artery is believed to have resulted from the fusion of the paired primitive umbilical arteries.It is suggested that the srn mutation causes a narrowing of the posterior amnion early in development. The resulting abnormal pressure causes a dorsal displacement of the hindgut, allowing fusion of the hindlimb buds. Abnormal structural relationships and pressure in the narrowed posteriior region disrupt normal urogenital and intestinal development and increase the proximity of the primitive umbilical arteries.
Histological and histochemical studies on the formation of statoblasts of a fresh‐water bryozoan, Pectinatella gelatinosa
Authors: Mukai Hideo 
Published: February 2005

AbstractThe course of the statoblast formation in Pectinatella gelatinosa was divided into four stages and studied histologically and histochemically. The bottom of the cystigenous cup is a center of cystigenous cell differentiation and the peripheral zone of the inner cystigenous layer turns to the outer cystigenous layer as the cystigenous cup grows. The annulus is formed by migration and transformation of the outer cystigenous cells.During early stages, the yolk cells have an intensely pyroninophilic or RNA‐rich cytoplasm. The cytoplasmic pyroninophilia then diminishes as the amount of yolk granules increases.Several kinds of yolk substances occur in the mature statoblast. During statoblast formation glycogen appears first, then glycoprotein and finally neutral unsaturated lipid.Acid phosphatase activity is associated with granular structures in the cytoplasm. In the cystigenous vesicle, acid phosphatase activity is low and confined to the apical extremity of the cell. Histochemically detectable alkaline phosphatase activity is not involved in the formation of the statoblast.
Histological development of the cement gland in Xenopus laevis: A light microscopic study
Authors: Lyerla Timothy A. , Pelizzari John J. 
Published: February 2005

AbstractThe differentiation and degeneration of the cement gland in Xenopus laevis is described. The gland is first observed histologically at stage 19 (neural tube stage) as a packed group of apical ectoderm cells heavily laden with oocyte pigment granules, lying ventral to the cranial neural fold. By tailbud stage 35/36, the gland cells have increased in height and are approximately ten times taller than nonglandular apical ectoderm cells. The nuclei divide the gland cells into an apical region that is eosinophilic and contains oocyte pigment granules, and a basal region that contains clear droplets. The cells are decreasing in height by stage 40 (early tadpole) and begin to lose their pigment granules. Between stages 45 and 48, the pigment is extruded and the clear basal droplets diminish in number. From stage 48 to 49 the cells become vacuolated and the histotypic characteristics of the functional gland are lost. The gland is not vascularized, nor do phagocytic cells appear in its vicinity during any stage of its development. It remains bordered at its base by subjacent basal ectoderm during its entire life cycle of 10 to 12 days at room temperature.
Innervation of abdominal paraganglia: An ultrastructural study
Authors: Mascorro Joe A. , Yates Robert D. 
Published: February 2005

AbstractAbdominal extra‐adrenal chromaffin tissue, or paraganglia, was examined at the ultrastructural level to elucidate the innervation of this adrenal medullary homologue. Paraganglia display unmyelinated nerve fibers surrounded by Schwann cell cytoplasm. These nerves are separated from the paraganglion Type I (granule‐containing) cells by cytoplasmic projections of paraganglion Type II (satellite) cells. However, serial sections show that the nerves eventually make synaptic contact with the Type I cell. At the axon‐chromaffin cell junction, only the outer aspect of the nerve is covered by the satellite cell. The presynaptic endings contain numerous synaptic vesicles, mitochondria and glycogen particles. The vesicles are predominantly of the clear‐cored variety, but a few possess centers which are elecron opaque. The pre‐ and postsynaptic membranes are separated bya subsynaptic space and occasionally exhibit the membranal densities usually associated with synaptic areas. These ultrastructural studies establish definite evidence that abdominal paraganglion cells are innervated.
Diversity in patterns of coital contact of mosquitoes: A scanning electron microscopic study
Authors: Spielman Andrew , Waterman Robert E. , Meller Samuel M. 
Published: February 2005

AbstractSpecimens, representative of each of the major taxa of mosquitoes, were fixed in copula and the external genitalia examined by scanning electron microscopy. The periphery of the basin‐like everted aedeagus of Aedus aegypti precisely matches that of the everted atrial membrane of the female. These structures are appressed during coitus and sealed by pressure of the paraprocts, aedeagal pouch and proctiger. When everted, the aedeagus of male Culex pipiens reveals a ridged dome that surrounds the genital opening. This dome seals itself laterally into a gutter formed by pad‐like extensions of the female's genital lips and is sealed dorsally by pressure of the aedeagal apodeme. The aedeagus of another culicine species, Wyeomyia smithii, bears the gonopore at the apex of a spined tube. This tube is inserted between the female's genital lips and is sealed within the genital atrium. The aedeagus of the toxorhynchitine species Toxorhynchitis brevipalpus is immobile and is inserted deep within the genital atrium of the female where it is sealed by pressure of the atrial walls. Males of each of these mosquitoes deliver a mixture of semen and sperm to the copulatory bursa of the female. After withdrawal of the aedeagus, sperm is transferred to the spermathecae.In contrast, sperm of Anopheles quadrimaculatus are delivered directly to the spermathecal duct. The tube‐like aedeagus is positioned by its leaflets during sperm transfer and is driven deep into the atrium, where a mixture of semen and sperm is ejaculated.The significance of mechanical barriers to mating between species is discussed.