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Journal of Morphology

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https://www.readbyqxmd.com/read/28333390/epithelial-crypts-a-complex-and-enigmatic-olfactory-organ-in-african-and-south-american-lungfish-lepidosireniformes-dipnoi
#1
Carolin Wittmer, Christine Nowack
African lungfish (Protopterus) seem unique among osteognathostomes in possessing a potential vomeronasal organ homolog in form of accessory epithelial crypts within their nasal cavity. Many details regarding structural and functional properties of these crypts are still unexplored. In this study, we reinvestigate the issue and also present the first data on epithelial crypts in the South American lungfish Lepidosiren paradoxa. The nasal cavities of L. paradoxa and Protopterus annectens were studied using histology, scanning electron microscopy, and alcian blue and PAS staining...
March 23, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28333389/the-cochlea-of-the-enigmatic-pygmy-right-whale-caperea-marginata-informs-mysticete-phylogeny
#2
Travis Park, Felix G Marx, Erich M G Fitzgerald, Alistair R Evans
The pygmy right whale, Caperea marginata, is the least understood extant baleen whale (Cetacea, Mysticeti). Knowledge on its basic anatomy, ecology, and fossil record is limited, even though its singular position outside both balaenids (right whales) and balaenopteroids (rorquals + grey whales) gives Caperea a pivotal role in mysticete evolution. Recent investigations of the cetacean cochlea have provided new insights into sensory capabilities and phylogeny. Here, we extend this advance to Caperea by describing, for the first time, the inner ear of this enigmatic species...
March 23, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28333368/morphological-specializations-of-the-yolk-sac-for-yolk-processing-in-embryonic-corn-snakes-pantherophis-guttatus-colubridae
#3
Kathryn G Powers, Daniel G Blackburn
Non-avian reptiles commonly are assumed to be like birds in their overall patterns of development. However, colubrid corn snakes (Pantherophis guttatus) have mechanisms of yolk cellularization and processing that are entirely different from the avian pattern. In birds, a vascular "yolk sac" surrounds and digests the liquid yolk. In contrast, in corn snakes, the yolk material is converted into vascularized cords of yolk-filled cells. In this study, we used stereomicroscopy, histology, and scanning electron microscopy to analyze this unusual developmental pattern in corn snakes...
March 23, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28261870/development-and-fate-of-the-postovulatory-follicle-complex-postovulatory-follicle-and-observations-on-folliculogenesis-and-oocyte-atresia-in-ovulated-common-snook-centropomus-undecimalis-bloch-1792
#4
Harry J Grier, Carole L Neidig, Irani Quagio-Grassiotto
The common snook, Centropomus undecimalis, was induced to ovulate using a time-release, GnRH analogue. Ovulation occurred the afternoon or evening the day after hormone administration. The time of ovulation was established within half an hour. At ovulation, three fish per time-group were divided into 0, 6, 12, 18 hr and one thru five days post-ovulation to study changes in the postovulatory follicle complex (POC). Histology of the ovaries revealed changes in the POC, postovulatory follicle (POF) and oocyte atresia through five days post-ovulation...
March 5, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28185320/orientation-of-the-lateral-semicircular-canal-in-xenarthra-and-its-links-with-head-posture-and-phylogeny
#5
Florence Coutier, Lionel Hautier, Raphaël Cornette, Eli Amson, Guillaume Billet
The orientation of the semicircular canals of the inner ear in the skull of vertebrates is one of the determinants of the capacity of this system to detect a given rotational movement of the head. Past functional studies on the spatial orientation of the semicircular canals essentially focused on the lateral semicircular canal (LSC), which is supposedly held close to horizontal during rest and/or alert behaviors. However, they generally investigated this feature in only a few and distantly related taxa. Based on 3D-models reconstructed from µCT-scans of skulls, we examined the diversity of orientations of the LSC within one of the four major clades of placental mammals, that is, the superorder Xenarthra, with a data set that includes almost all extant genera and two extinct taxa...
February 10, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28182299/tentacle-structure-in-freshwater-bryozoans
#6
Yuta Tamberg, Natalia Shunatova
Tentacles are the main food-gathering organs of bryozoans. The most common design is a hollow tube of extracellular matrix (ECM), covered with ten columns of epithelial cells on the outside, and a coelothelium on the inside. Nerves follow the ECM, going between the bases of some epidermal cells. The tentacle musculature includes two bundles formed by myoepithelial cells of the coelothelium. The tentacles of freshwater (phylactolaemate) bryozoans, however, differ somewhat in structure from those of marine bryozoans...
February 9, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28182298/looking-into-the-puparium-micro-ct-visualization-of-the-internal-morphological-changes-during-metamorphosis-of-the-blow-fly-calliphora-vicina-with-the-first-quantitative-analysis-of-organ-development-in-cyclorrhaphous-dipterans
#7
Daniel Martín-Vega, Thomas J Simonsen, Martin J R Hall
Metamorphosis of cyclorrhaphous flies takes place inside a barrel-like puparium, formed by the shrinking, hardening and darkening of the third-instar larval cuticle. The opacity of this structure hampers the visualization of the morphological changes occurring inside and therefore a full understanding of the metamorphosis process. Here, we use micro-computed tomography (micro-CT) to describe the internal morphological changes that occur during metamorphosis of the blow fly, Calliphora vicina Robineau-Desvoidy 1830 (Diptera: Calliphoridae) at a greater temporal resolution than anything hitherto published...
February 9, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28182295/development-of-cranial-muscles-in-the-actinopterygian-fish-senegal-bichir-polypterus-senegalus-cuvier-1829
#8
Masatsugu Noda, Tsutomu Miyake, Masataka Okabe
Polypterus senegalus Cuvier, 1829 is one of the most basal living actinopterygian fish and a member of the Actinopterygii. We analyzed the spatial and temporal pattern of cranial muscle development of P. senegalus using whole-mount immunostaining and serial sectioning. We described the detailed structure of the external gill muscles which divided into dorsal and ventral parts after yolk exhaustion. The pattern of the division is similar to that of urodeles. We suggest that, the external gill muscles of P. senegalus are involved in spreading and folding of the external gill stem and the branches...
February 9, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28176372/development-of-the-skull-and-pectoral-girdle-in-siberian-sturgeon-acipenser-baerii-and-russian-sturgeon-acipenser-gueldenstaedtii-acipenseriformes-acipenseridae
#9
Peter Warth, Eric J Hilton, Benjamin Naumann, Lennart Olsson, Peter Konstantinidis
The head is considered the major novelty of the vertebrates and directly linked to their evolutionary success. Its form and development as well as its function, for example in feeding, is of major interest for evolutionary biologists. In this study, we describe the skeletal development of the cranium and pectoral girdle in Siberian (Acipenser baerii) and Russian sturgeon (A. gueldenstaedtii), two species that are commonly farmed in aquaculture and increasingly important in developmental studies. This study comprises the development of the neuro-, viscero- and dermatocranium and the dermal and chondral components of the pectoral girdle, from first condensation of chondrocytes in prehatchlings to the early juvenile stage and reveals a clear pattern in formation...
February 7, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28168744/functional-morphology-of-amplexus-clasping-in-spinicaudatan-clam-shrimps-crustacea-branchiopoda-and-its-evolution-in-bivalved-branchiopods-a-video-based-analysis
#10
Zandra M S Sigvardt, D Christopher Rogers, Jørgen Olesen
Male clam shrimps (Crustacea: Branchiopoda: Laevicaudata, Spinicaudata, and Cyclestherida) have their first one or two trunk limb pairs modified as "claspers," which are used to hold the female during mating and mate guarding. Clasper morphology has traditionally been important for clam shrimp taxonomy and classification, but little is known about how the males actually use the claspers during amplexus (clasping). Homologies of the various clasper parts ("movable finger," "large palp," "palm," "gripping area," and "small palp") have long been discussed between the three clam shrimp taxa, and studies have shown that only some structures are homologous while others are convergent ("partial homology")...
February 6, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28168721/yolk-sac-development-in-lizards-lacertilia-scincidae-new-perspectives-on-the-egg-of-amniotes
#11
James R Stewart, Michael B Thompson
Embryos of oviparous reptiles develop on the surface of a large mass of yolk, which they metabolize to become relatively large hatchlings. Access to the yolk is provided by tissues growing outward from the embryo to cover the surface of the yolk. A key feature of yolk sac development is a dedicated blood vascular system to communicate with the embryo. The best known model for yolk sac development and function of oviparous amniotes is based on numerous studies of birds, primarily domestic chickens. In this model, the vascular yolk sac forms the perimeter of the large yolk mass and is lined by a specialized epithelium, which takes up, processes and transports yolk nutrients to the yolk sac blood vessels...
February 6, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28168720/external-morphogenesis-of-the-tardigrade-hypsibius-dujardini-as-revealed-by-scanning-electron-microscopy
#12
Vladimir Gross, Irene Minich, Georg Mayer
Tardigrada, commonly called water bears, is a taxon of microscopic panarthropods with five-segmented bodies and four pairs of walking legs. Although tardigrades have been known to science for several centuries, questions remain regarding many aspects of their biology, such as embryogenesis. Herein, we used scanning electron microscopy to document the external changes that occur during embryonic development in the tardigrade Hypsibius dujardini (Eutardigrada, Parachela, Hypsibiidae). Our results show an accelerated development of external features, with approximately 30 hrs separating the point at which external structures first become recognizable and a fully formed embryo...
February 6, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28165149/post-metamorphic-development-of-skin-glands-in-a-true-toad-parotoids-versus-dorsal-skin
#13
Eleonora Regueira, Camila Dávila, Alina G Sassone, María E Ailín O'Donohoe, Gladys N Hermida
Chemical defenses in amphibians are a common antipredatory and antimicrobial strategy related to the presence of dermal glands that synthesize and store toxic or unpalatable substances. Glands are either distributed throughout the skin or aggregated in multiglandular structures, being the parotoids the most ubiquitous macrogland in toads of Bufonidae. Even though dermal glands begin to develop during late-larval stages, many species, including Rhinella arenarum, have immature glands by the end of metamorphosis, and their post-metamorphic growth is unknown...
February 6, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28165148/a-correlative-study-of-the-allantois-in-pig-and-rabbit-highlighting-the-diversity-of-extraembryonic-tissues-in-four-mammalian-species-including-mouse-and-man
#14
Waad Hassan, Christoph Viebahn
Despite its conserved role in placenta and umbilical cord formation, the mammalian allantois shows remarkable diversity in size and form as well as in the timing of its appearance and attachment to the chorion. In the mouse, the common allantoic diverticulum is lacking; instead, the allantoic core domain is defined as a progenitor center for allantoic development. In this study, the allantoises of the pig and the rabbit as two nonrodent mammals of increasing significance in biomedical research are compared (1) morphologically using high resolution light and electron microscopy and (2) molecularly using brachyury mRNA expression as a mesodermal marker...
February 6, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28165147/a-review-on-the-morphology-of-ovarian-follicles-in-elasmobranchs-a-case-study-in-rhizoprionodon-taylori
#15
REVIEW
Daniela S Waltrick, Colin A Simpfendorfer, Cynthia A Awruch
The identification of the elasmobranch secondary ovarian follicles and their function can be challenging and the inconsistent use of terminology derived from other taxa is a matter of ongoing debate. In this study, the available information on the histology of the elasmobranch secondary ovarian follicles derived from atresia (preovulatory follicles) or ovulation (postovulatory follicles) is reviewed highlighting their morphology and steroidogenic capacity. Based on this literature review, the ovarian follicles of the Australian sharpnose shark Rhizoprionodon taylori were classified according to their preovulatory or postovulatory origin...
February 6, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28164360/new-insights-into-the-spermatogenesis-of-the-black-tiger-prawn-penaeus-monodon
#16
Tianyi Feng, Brian Paterson, Stephen Johnston
This study reports a comprehensive description of penaeid spermatogenesis (Penaeus monodon) by light and transmission electron microscopy. A conspicuous characteristic of spermatocytogenesis was a ring-like structure with high electron-density adjacent to the nucleus of a primary spermatocyte. During the spermiogenesis from stage I (StI) to stage VI spermatid (StVI), the formation of the acrosome and decondensation of the nucleus were the most notable morphological transformations. StIs were small and compact and they were contained in the syncytia...
February 5, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28145573/static-osteogenesis-does-not-precede-dynamic-osteogenesis-in-periosteal-ossification-of-pleurodeles-caudata-amphibia-and-pogona-squamata-lepidosauria
#17
Jorge Cubo, Mylaine Hui, François Clarac, Alexandra Quilhac
Two successive mechanisms have been described in perichondral ossification: (1) in static osteogenesis, mesenchymal cells differentiate into stationary osteoblasts oriented randomly, which differentiate into osteocytes in the same site; (2) in dynamic osteogenesis, mesenchymal cells differentiate into osteoblasts that are all oriented in the same direction and move back as they secrete collagen fibers. This study is aimed at testing the hypothesis that the ontogenetic sequence static then dynamic osteogenesis observed in the chicken and in the rabbit is homologous and was acquired by the last common ancestor of amniotes or at a more inclusive node...
February 1, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28145572/placentation-in-watersnakes-i-placental-histology-and-development-in-north-american-nerodia-colubridae-natricinae
#18
Daniel G Blackburn, Kristie E Anderson, Kera W Aronson, Mary K Burket, Jessica F Chin, Susan K San-Francisco, Ian P Callard
As part of a broad survey of placental structure, function, and evolution in reptilian sauropsids paraffin-section histology was used to study microscopic anatomy of the uterus and fetal membranes of three species of North American watersnakes (Nerodia: Colubridae). The pre-ovulatory uterus is poorly vascularized with inactive shell glands. These shell glands are activated during vitellogenesis but regress during pregnancy. Two placentas develop through apposition of the uterine lining to the chorioallantois and the yolk sac omphalopleure...
February 1, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28145561/placentation-in-watersnakes-ii-placental-ultrastructure-in-nerodia-erythrogaster-colubridae-natricinae
#19
Daniel G Blackburn, Kristie E Anderson, Amy R Lo, Emily C Marquez, Ian P Callard
Ultrastructure of the placental tissues from redbelly watersnakes (Nerodia erythrogaster) was analyzed during late pregnancy to provide insight into placental development and function. Examination of the chorioallantoic placenta with transmission electron microscopy reveals that chorionic and uterine epithelia are extremely attenuated but intact and that the eggshell membrane is vestigial and lacks a calcareous layer. These features minimize the interhemal diffusion distance across the placenta. Scanning electron microscopy reveals that fetal and maternal components of the placentas are richly vascularized by dense networks of capillaries...
February 1, 2017: Journal of Morphology
https://www.readbyqxmd.com/read/28145089/the-relationship-between-diet-and-tooth-complexity-in-living-dentigerous-saurians
#20
Keegan M Melstrom
Living saurian reptiles exhibit a wide range of diets, from carnivores to strict herbivores. Previous research suggests that the tooth shape in some lizard clades correlates with diet, but this has not been tested using quantitative methods. I investigated the relationship between phenotypic tooth complexity and diet in living reptiles by examining the entire dentary tooth row in over 80 specimens comprising all major dentigerous saurian clades. I quantified dental complexity using orientation patch count rotated (OPCR), which discriminates diet in living and extinct mammals, where OPCR-values increase with the proportion of dietary plant matter...
January 31, 2017: Journal of Morphology
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