The morphology of the parasitic isopod Tachaea chinensis (Isopoda, Cymothoida) revealed through scanning electron microscopy and histological analysis

Crustaceana ◽  
2021 ◽  
Vol 94 (1) ◽  
pp. 63-75
Author(s):  
Xin Li ◽  
Qijun Chen ◽  
Yingdong Li

Abstract Parasitic isopods have negative effects on several commercially important fishes and crustaceans. However, studies on these parasites, especially on their morphology, are limited. In the present study, scanning electron microscopy and simultaneous histological analysis were carried out to examine the external structure and composition of the internal organs of Tachaea chinensis (Isopoda, Corallanidae). Seven pairs of pereopods are sharp and hook-like, which are used for attaching to the host. Four pairs of the paddle-shaped pleopods indicate that it has the ability to swim freely. Analysis of the mouth appendages revealed that T. chinensis mainly feeds on the host’s blood. Moreover, we found numerous glands, including the salivary glands and hepatopancreas, in the coelom; loose connective tissue was also found in the ventral body cavity, which appeared to be a vestigial gonad. In addition, the description of the gland also provides valuable empirical data for future research.

Author(s):  
M. Barson ◽  
A. Avenant-Oldewage

Sharptooth catfish, Clarias gariepinus, from the Rietvlei Dam near Pretoria, South Africa were examined for internal platyhelminth parasites. Two adult cestodes, Polyonchobothrium clarias (stomach) (prev alence 71 %, mean intensity = 5, n = 7) and Proteocephalus glanduliger (anterior intestine) (prevalence 14 %, mean intensity = 2, n = 7), were found in the gut while metacercariae of one larval digenean, Ornithodiplostomum sp. (prevalence 14 %, mean intensity = 140, n = 7), were found encysted in the muscles. The morphology of these species, based on light and scanning electron microscopy as well as histological analysis, and how they differ from previously described specimens, are discussed. Ornithodiplostomum is a new record in southern Africa. Infection levels of the host fish were mild compared to records from previous surveys.


2013 ◽  
Vol 151 (3) ◽  
pp. 517-533 ◽  
Author(s):  
DAVID M. MARTILL ◽  
PETER J. A. DEL STROTHER ◽  
FLORENCE GALLIEN

AbstractAn association of diverse hollow spines and dermal denticles (ichthyoliths) from the Carboniferous (Westphalian) of Todmorden, Yorkshire, England are attributed to a new genus of enigmatic shark that may lie close to Listracanthus Newberry & Worthen, 1870. Scanning electron microscopy shows that denticle morphology is highly variable, but forms a morphocline including elongate multi-spined elements as well as robust dome-like stellate denticles and recurved spinose elements. Histological analysis suggests an absence of enameloid. Continuous variation of form between elongate multi-cusped spines to boss-like circular denticles shows that all previously described Palaeozoic species of Listracanthus are probably junior synonyms of the type species L. hystrix Newberry & Worthen, 1870. The status of Listracanthus as a surviving ‘Lilliputian’ taxon after the Permian extinction is questioned. Although the new specimen has affinities with Listracanthus, significant differences in the form of the posterior spines on elongate denticles warrants its placement in the new genus Acanthorhachis gen. nov. The family Listracanthidae is erected to accommodate Listracanthus and Acanthorhachis.


Plants ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 144 ◽  
Author(s):  
NG Ja Ming ◽  
Suraiya Binte Mostafiz ◽  
Nur Syafiqoh Johon ◽  
Nur Saliha Abdullah Zulkifli ◽  
Alina Wagiran

The development of efficient tissue culture protocol for somatic embryo would facilitate the genetic modification breeding program. The callus induction and regeneration were studied by using different parameters i.e., auxins, cytokinins, and desiccation treatment. Scanning electron microscopy and histological analysis were performed to identify the embryogenic callus for regeneration. The callus percentage results showed that MS (Murashige and Skoog) basal medium supplemented with 3 mg/L 2, 4-D and 30g/L maltose were the optimal callus induction medium for MR220 (80%) and MR220-CL2 (95%). The morphology of the embryogenic callus was confirmed by the SEM (Scanning Electron Microscopy) (presence of extracellular matrix surface network) and later by histological analysis. Finally, MS media supplemented with 0.5 mg/L NAA (Naphthalene Acetic Acid), 2 mg/L kin, and 1 mg/L BAP were selected as the optimum regeneration media treatment while callus desiccated for 48 h was proved to produce more plantlets in MR220 (60%) and MR220-CL2 (73.33%) compared to control treatment (without desiccation). The protocol presented here showed the necessity for the inclusion of partial desiccation as an important step in the tissue culture protocol of Malaysian indica rice genotypes in order to enhance their regeneration potential.


1999 ◽  
Vol 77 (7) ◽  
pp. 1111-1116 ◽  
Author(s):  
D D Tajrine ◽  
N N Kapoor ◽  
J D McLaughlin

In this study, changes were examined in surface structures and tegumental morphology of newly excysted, migrating, and adult Cyclocoelum mutabile obtained from experimentally infected coots (Fulica americana). Newly excysted juveniles were spinous and had two large depressions situated at the anterior tip of the body and a large acetabulum. Small papillae were scattered around the mouth region and also formed a row that encircled the anterior end of the fluke. Four groups of larger papillae, two ventrolateral and two lateral, originated from points slightly posterior to the mouth region. The two ventrolateral bands of papillae terminated slightly posterior to the acetabulum; the two lateral rows of papillae terminated about three-quarters of the length along the specimen. Six large multilobed papillae were associated with the acetabulum. Juveniles migrating through the liver lost the spines and papillae by day 6, but the anterior depressions persisted into the adult stage. The tegument of 6- and 12-day-old flukes was smooth with a varying number of transverse folds. The tegument of 15-day-old specimens from the body cavity ranged in appearance from folded and pitted to reticulate. The reticulations were more prominent in adults and the entire body was covered with a reticulate pattern of loculus-like structures that are believed to aid in the movement of the flukes within the air sacs of the coot host.


Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 555
Author(s):  
Wei Yuan ◽  
Renfeng Yang ◽  
Jianyou Yu ◽  
Shixin Zhou ◽  
Shaoqian Cui ◽  
...  

This article aims to improve the toughness of pre-packaged grouts (PPG) by incorporating crumb rubber. The mechanism for toughness of PPG with crumb rubber was analyzed based on the uniaxial compression model. Crumb rubber with surfaces treated by different methods (NaOH solutions or microwave treatment) was observed by scanning electron microscopy (SEM). The effects of mesh sizes, amounts, surface-treated methods of crumb rubber, and mixing procedures on the PPG’s mechanical strength and rheological properties were investigated. The results showed that, firstly, the addition of crumb rubber improves the PPG’s toughness, while its mechanical strength is reduced. Adding NaOH solutions or microwave-treated crumb rubber into PPG can weaken the negative effects of crumb rubber on the PPG’s mechanical strength; however, this function is limited. Secondly, the crumb rubber grouts’ rheological properties can be fully exploited by increasing the stirring rate and time so that the fluidity of crumb rubber grouts is improved, which fulfils the characteristics of no bleeding and micro-expansion. Finally, the optimal formula and mixing technique of crumb rubber grouts were proposed in this paper.The results of this paper can provide a significant reference for the application of scrap tires.


Author(s):  
P.S. Porter ◽  
T. Aoyagi ◽  
R. Matta

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.


Author(s):  
P.J. Dailey

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.


Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).


Author(s):  
Ronald H. Bradley ◽  
R. S. Berk ◽  
L. D. Hazlett

The nude mouse is a hairless mutant (homozygous for the mutation nude, nu/nu), which is born lacking a thymus and possesses a severe defect in cellular immunity. Spontaneous unilateral cataractous lesions were noted (during ocular examination using a stereomicroscope at 40X) in 14 of a series of 60 animals (20%). This transmission and scanning microscopic study characterizes the morphology of this cataract and contrasts these data with normal nude mouse lens.All animals were sacrificed by an ether overdose. Eyes were enucleated and immersed in a mixed fixative (1% osmium tetroxide and 6% glutaraldehyde in Sorenson's phosphate buffer pH 7.4 at 0-4°C) for 3 hours, dehydrated in graded ethanols and embedded in Epon-Araldite for transmission microscopy. Specimens for scanning electron microscopy were fixed similarly, dehydrated in graded ethanols, then to graded changes of Freon 113 and ethanol to 100% Freon 113 and critically point dried in a Bomar critical point dryer using Freon 13 as the transition fluid.


Author(s):  
Jane A. Westfall ◽  
S. Yamataka ◽  
Paul D. Enos

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).


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