scholarly journals Sperm ultrastructure of Pochazia shantungensis (Chou & Lu) and Ricania speculum (Walker) (Hemiptera, Ricaniidae) with phylogenetic implications

ZooKeys ◽  
2019 ◽  
Vol 880 ◽  
pp. 43-59
Author(s):  
Zhen Jiang ◽  
Jianing Liu ◽  
Daozheng Qin
Keyword(s):  
Neck Region ◽  
Mature Spermatozoon ◽  
Current Evidence ◽  
Sperm Ultrastructure ◽  
Transmission Electron ◽  
Phylogenetic Implications ◽  
Dense Substance ◽  
The Individual ◽  
Relationship Of ◽  
Centriole Adjunct

The sperm ultrastructure of two ricaniid species, Pochazia shantungensis (Chou & Lu) and Ricania speculum (Walker), was investigated using light and transmission electron microscopy. Both species have monoflagellate sperm, the shape and ultrastructure of the mature spermatozoon of these two species are similar in morphology, and 128 spermatozoa are organized into sperm bundles with their heads embedded in a homogenous matrix forming the spermatodesmata. The individual sperm is filiform and includes the head, neck and flagellum. The head is needle-like, with a bilayer acrosome and an inferior elongated nucleus which is formed of homogeneously compact and electron-dense chromatin. The neck region is indistinct and is comprised of the centriole and centriole adjunct with a homogeneous dense substance. The long flagellum has the typical 9 + 9 + 2 axoneme microtubule pattern and two symmetrical mitochondrial derivatives with an orderly array of cristae flanking both sides, and a pair of well-developed fishhook-shaped accessory bodies. Current evidence shows that ricaniid species have D-shaped mitochondrial derivatives in cross-section and a serrated electron-dense region. The phylogenetic relationship of Fulgoroidea with other superfamilies in Auchenorrhyncha is briefly discussed.

Spermatogenesis and the fine structure of the mature spermatozoon of the liver fluke, Fasciola hepatica (Trematoda: Digenea)

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 395-407 ◽  
Author(s):  
A. W. Stitt ◽  
I. Fairweather
Keyword(s):  
Fine Structure ◽  
Liver Fluke ◽  
Central Body ◽  
Fasciola Hepatica ◽  
Mature Spermatozoon ◽  
Basal Bodies ◽  
Nuclear Region ◽  
Sperm Ultrastructure ◽  
Transmission Electron ◽  
Median Process

SUMMARYSpermatogenesis and the fine structure of the mature spermatozoon of Fasciola hepatica have been studied by transmission electron microscopy. The primary spermatogonia display a typical gonial morphology and occupy the periphery of the testis. They undergo 3 mitotic divisions to give rise to 8 primary spermatocytes forming a rosette of cells connected to a central cytophore. The primary spermatocytes undergo 2 meiotic divisions, resulting in 32 spermatids that develop into spermatozoa. Intranuclear synaptonemal complexes in primary spermatocytes confirm the first meiotic division. The onset of spermiogenesis is marked by the formation of the zone of differentiation which contains 2 basal bodies and a further centriole derivative, the central body. The zone extends away from the spermatid cell to form the median process; into this migrates the differentiated and elongate nucleus. Simultaneously, 2 axonemes develop from the basal bodies. During development, they rotate through 90° to extend parallel to the median process. The migration of the nucleus to the distal end of the median process coincides with the fusion of the axonemes to the latter to form a monopartite spermatozoon. The mature spermatozoon possesses 2 axonemes of the 9 + ‘1’ pattern typical of parasitic platyhelminths, 2 elongate mitochondria and a variable array of peripheral microtubules. The nuclear region of the spermatozoon is immotile. The value of sperm ultrastructure as a taxonomic tool in platyhelminth phylogeny is discussed.

Epitaxial Growth and Stability of C49 TiSi2 ON Si(111).

1990 ◽  
Vol 198 ◽  
Author(s):  
Hyeongtag Jeon ◽  
J. W. Honeycutt ◽  
C. A. Sukow ◽  
T. P. Humphreys ◽  
R. J. Nemanich ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Metastable Phase ◽  
Plan View ◽  
Transmission Electron ◽  
Temperature Deposition ◽  
The Individual ◽  
Relationship Of

ABSTRACTEpitaxial TiSi2 films have been grown by molecular beam epitaxy (MBE) on atomically clean Si(111)-orientated substrates. The growth procedure involves the ambient temperature deposition of Ti films of 50Å thickness and annealing to 800°C. In situ low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) techniques have been used to monitor the TiSi2 formation process. The epitaxial films have been identified as the C49 metastable phase by both Raman spectroscopy and electron diffraction. Plan view transmission electron microscopy shows three different connected island morphologies. The individual island structures are single crystal and are grown epitaxially with different crystallographic orientations. The orientational relationship of the largest islands is given by [3 1 1] C49 TiSi2//[112]Si and (130) C49 TiSi2//(l1 1)Si. High resolution transmission electron microscopy (HRTEM) cross-section shows a coherent interface extending over several hundred angstroms.

Ultrastructure of spermatogenesis and the mature spermatozoon of Haplobothrium globuliforme Cooper, 1914 (Cestoda: Haplobothrioidea)

1985 ◽  
Vol 63 (6) ◽  
pp. 1478-1487 ◽  
Author(s):  
Barbara M. MacKinnon ◽  
Michael D. B. Burt
Keyword(s):  
Volume Ratio ◽  
Mature Spermatozoon ◽  
Nuclear Volume ◽  
Sperm Cells ◽  
Basal Bodies ◽  
Sperm Ultrastructure ◽  
Cytoplasmic Extension ◽  
Transmission Electron ◽  
Regular Arrangement ◽  
Dense Nucleus

The process of spermatogenesis and the structure of the mature spermatozoon of Haplobothrium globuliforme Cooper, 1914 were examined using transmission electron microscopy. Spermatogonia have a low cytoplasmic to nuclear volume ratio, and contain numerous free ribosomes and few mitochondria. Quaternary spermatogonia have a rosette appearance with the eight nuclei surrounding a central cytoplasmic cytophore. Spermatocytes, the largest of the developing sperm cells, contain free ribosomes and several mitochondria with pronounced cristae. No synaptonemal complexes and few endoplasmic reticulum formations were seen. Early spermatids show a regular arrangement of the nucleus, Golgi apparatus, and mitochondria. This regularity is disrupted as spermiogenesis commences, with the formation of the zone of differentiation, a conical indentation of the spermatid cytoplasm. This zone of differentiation is bordered by microtubules. Within the zone develop two interconnected basal bodies with their respective flagellar rootlets. From each basal body arises an axoneme with the 9 + "1" microtubular configuration. The axonomes elongate, eventually fusing with a cytoplasmic extension of the zone of differentiation, and the condensed nucleus migrates into the sperm body. The mature spermatozoon is elongate (30 μm long) and slender, and possesses an electron-dense nucleus, two lateral axonemes, α and β glycogen, and peripheral microtubules. The importance of sperm ultrastructure with respect to phylogeny is discussed.

Spermiogenesis in two paramphistomes from Nile fish in Egypt: an ultrastructural study

2007 ◽  
Vol 81 (3) ◽  
pp. 219-226 ◽  
Author(s):  
A.A. Ashour ◽  
K. Garo ◽  
I.S. Gamil
Keyword(s):  
Electron Microscopy ◽  
Mature Spermatozoon ◽  
Basal Bodies ◽  
Sperm Ultrastructure ◽  
Parasitic Helminths ◽  
Ultrastructural Studies ◽  
Cytoplasmic Extension ◽  
Transmission Electron ◽  
Digenetic Trematodes ◽  
External Ornamentation

AbstractThe process of spermiogenesis in two paramphistomes,Sandonia sudanensisandBasidiodiscus ectorchisfrom the Nile fishSynodontis schallin Egypt was studied by transmission electron microscopy. Spermiogenesis is characterized by the outgrowth of the zone of differentiation, presenting two basal bodies separated by a microtubule organizing centre, each basal body developing into a flagellum. Proximodistal fusion of these flagella with a median cytoplasmic extension gives rise to the spermatozoon. The mature spermatozoon possesses two axonemes of the 9+‘1’ pattern typical of parasitic helminths. There are few ultrastructural studies on spermiogenesis in paramphistomes, which are considered the most primitive digenetic trematodes. The present study provides new and more detailed information on this process, including the presence of a lateral flange and external ornamentation of the cell membrane. The value of sperm ultrastructure as a taxonomic tool in phylogeny is also discussed.

COVID-19 in children: Pathogenesis and current status

2020 ◽  
Author(s):  
Lawrence Frenkel ◽  
Fernando Gomez ◽  
Joseph A Bellanti
Keyword(s):  
Respiratory Disease ◽  
Respiratory Symptoms ◽  
Distress Syndrome ◽  
Clinical Course ◽  
Current Status ◽  
Current Evidence ◽  
Initial Description ◽  
Relationship Of ◽  
Inflammatory Syndrome ◽  
The Relationship

Background: Since its initial description in December 2019 in Wuhan, China, coronavirus disease 2019 (COVID-19) has rapidly progressed into a worldwide pandemic, which has affected millions of lives. Unlike the disease in adults, the vast majority of children with COVID-19 have mild symptoms and are largely spared from severe respiratory disease. However, thereare children who have significant respiratory disease, and some may develop a hyperinflammatory response similar to thatseen in adults with COVID-19 and in children with Kawasaki disease (KD), which has been termed multisystem inflammatory syndrome in children (MIS-C).Objective: The purpose of this report was to examine the current evidence that supports the etiopathogenesis of COVID-19 in children and the relationship of COVID-19 with KD and MIS-C as a basis for a better understanding of the clinical course, diagnosis, and management of these clinically perplexing conditions.Results: The pathogenesis of COVID-19 is carried out in two distinct but overlapping phases of COVID-19: the first triggered by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) itself and the second by the host immune response. Children with KD have fewer of the previously described COVID-19–associated KD features with less prominent acute respiratory distress syndrome and shock than children with MIS-C.Conclusion: COVID-19 in adults usually includes severe respiratory symptoms and pathology, with a high mortality. Ithas become apparent that children are infected as easily as adults but are more often asymptomatic and have milder diseasebecause of their immature immune systems. Although children are largely spared from severe respiratory disease, they canpresent with a SARS-CoV-2–associated MIS-C similar to KD.

CHILD-PARENT RELATIONS AS A FACTOR IN THE FORMATION OF PROFESSIONAL PREFERENCES IN PEDAGOGICAL DYNASTIES

2020 ◽  
Vol 2 (4) ◽  
pp. 126-130
Author(s):  
N. V. SHAMANIN ◽  
Keyword(s):  
Professional Development ◽  
The Family ◽  
The Individual ◽  
Relationship Of ◽  
The Relationship ◽  
Parent Child Relationships ◽  
Professional Preferences ◽  
Parent Child

The article raises the issue of the relationship of parent-child relationships and professional preferences in pedagogical dynasties. Particular attention is paid to the role of the family in the professional development of the individual. It has been suggested that there is a relationship between parent-child relationships and professional preferences.

Epilogue

2017 ◽  
Author(s):  
Joshua S. Walden
Keyword(s):  
The Body ◽  
The Self ◽  
The Individual ◽  
Relationship Of ◽  
The Relationship

The book’s epilogue explores the place of musical portraiture in the context of posthumous depictions of the deceased, and in relation to the so-called posthuman condition, which describes contemporary changes in the relationship of the individual with such aspects of life as technology and the body. It first examines Alfred Hitchcock’s Vertigo to view how Bernard Herrmann’s score relates to issues of portraiture and the depiction of the identity of the deceased. It then considers the work of cyborg composer-artist Neil Harbisson, who has aimed, through the use of new capabilities of hybridity between the body and technology, to convey something akin to visual likeness in his series of Sound Portraits. The epilogue shows how an examination of contemporary views of posthumous and posthuman identities helps to illuminate the ways music represents the self throughout the genre of musical portraiture.

Spermiogenesis and sperm ultrastructure of Carmyerius endopapillatus (Digenea, Gastrothylacidae), a parasite of Bos taurus in Senegal

2008 ◽  
Vol 53 (1) ◽  
Author(s):  
Momar Seck ◽  
Bernard Marchand ◽  
Cheikh Bâ
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ultrastructural Study ◽  
Bos Taurus ◽  
Posterior Extremity ◽  
Sperm Ultrastructure ◽  
Lateral Expansion ◽  
Transmission Electron ◽  
Plasmic Membrane ◽  
Flagellar Rotation

AbstractUltrastructural study of spermiogenesis and of the spermatozoon of Carmyerius endopapillatus has enabled to describe some characteristics of this digenea. The intercentriolar body situated between the two striated roots and the two centrioles, presents a symmetric organization. Both external bands of this intercentriolar body are made up of a row of granules. During spermiogenesis, a flagellar rotation of 90° is described. The old spermatid does not present external ornamentations. The spermatozoon is characterized, in its anterior region, by the presence of a lateral expansion exhibiting one spinelike body. In C. endopapillatus, external ornamentations are localized only at the level where the lateral expansion appears. The posterior extremity of spermatozoon exhibits a nucleus surrounded by a plasmic membrane lacking microtubules, but presenting a small lateral expansion. This is the first species of Gastrothylacidae family studied by transmission electron microscopy.

Epitaxial Growth of AlN Thin Films on Silicon and Sapphire by Pulsed Laser Deposition

1995 ◽  
Vol 395 ◽  
Author(s):  
R.D. Vispute ◽  
H. Wu ◽  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
Pulsed Laser Deposition ◽  
Laser Energy ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Breakdown Field ◽  
Transmission Electron ◽  
Uv Visible ◽  
Relationship Of

ABSTRACTAIN thin films have been grown epitaxially on Si(111) and Al2O3(0001) substrates by pulsed laser deposition. These films were characterized by FTIR and UV-Visible, x-ray diffraction, high resolution transmission electron and scanning electron microscopy, and electrical resistivity. The films deposited on silicon and sapphire at 750-800°C and laser energy density of ∼ 2 to 3J/cm2 are epitaxial with an orientational relationship of AIN[0001]║ Si[111], AIN[2 110]║Si[011] and AlN[0001]║Al2O3[0001], AIN[1 2 1 0]║ Al2O3[0110] and AIN[1010] ║ Al2O3[2110]. The both AIN/Si and AIN/Al2O3 interfaces were found to be quite sharp without any indication of interfacial reactions. The absorption edge measured by UV-Visible spectroscopy for the epitaxial AIN film grown on sapphire was sharp and the band gap was found to be 6.1eV. The electrical resistivity of the films was about 5-6×l013Ω-cm with a breakdown field of 5×106V/cm. We also found that the films deposited at higher laser energy densities ≥10J/cm2 and lower temperatures ≤650°C were nitrogen deficient and containing free metallic aluminum which degrade the microstructural, electrical and optical properties of the AIN films

Prediction of pre-eclampsia

2021 ◽  
pp. 1753495X2098401
Author(s):  
Konstantinos Giannakou
Keyword(s):  
Early Recognition ◽  
Routine Care ◽  
Current Evidence ◽  
Individual Risk ◽  
Negative Consequences ◽  
Predictive Tool ◽  
Mortality And Morbidity ◽  
Maternal Mortality And Morbidity ◽  
Conducting Research ◽  
The Individual

Pre-eclampsia is a leading cause of neonatal and maternal mortality and morbidity that complicates approximately 2–8% of all pregnancies worldwide. The precise cause of pre-eclampsia is not completely understood, with several environmental, genetic, and maternal factors involved in its pathogenesis and pathophysiology. An accurate predictor of pre-eclampsia will facilitate early recognition, close surveillance according to the individual risk and early intervention, and reduce the negative consequences of the disorder. Current evidence shows that no single test predicts pre-eclampsia with sufficient accuracy to be clinically useful. A combination of markers into multiparametric models may provide a more useful and feasible predictive tool for pre-eclampsia screening in the routine care setting than a test of either component alone. This review presents a summary of the current advances on prediction of pre-eclampsia, highlighting their performance and applicability. Key priorities when conducting research on predicting pre-eclampsia are also analyzed.

Sign in / Sign up

Export Citation Format

Share Document