Testis Development and Ultrastructural Features During Spermatogenesis in Cultured Small Yellow Croaker,Larimichthys polyactis

The small yellow croaker Larimichthys polyactis is an economically important marine fish in Northeast Asia.Currently,its natural resources are threatened by overfishing and environmental pollution.Therefore,research on the reproductive system of the fish is crucial.Here,we studied the testis development and ultrastructural features of spermatogenesis in cultured L.polyactis using anatomical,histological,and ultrastructural techniques.A pair of testes,consisting of a central sperm duct and radial seminiferous lobules,were observed.The reproduction cycle of testes can be divided into stages I–VI.March to May was confirmed as the breeding season for male L.polyactis,while April is the ideal period for artificial breeding.The male L.polyactis can attain sexual maturity within 1 year.The spermatogenesis of L.polyactis comprised spermatogonium,spermatocyte,spermatid,and mature spermatozoon.The morphology of spermatogenic cells changed obviously during spermiogenesis,including nuclear shaping,midpiece and flagellum formation.The mature sperms consist of an ellipsoidal head,a short midpiece,and a long flagellum.The anterior of the head with a kidney-shaped nucleus can be distinguished.The midpiece is located posterior to the head and includes four to six spherical mitochondria.The flagellum has irregular lateral fins.The testis of L.polyactis is an unrestricted lobular type,with cystic spermatogenesis,type II spermiogenesis,and type II spermatozoa.These features are highly similar to those of other Sciaenid species.Our findings provide useful insights into the mechanism underlying testis development and spermatogenesis of L.polyactis,which can facilitate the artificial breeding of this species.

Ultrastructural Study of Secondary Wall Formation in the Stem Fiber of Phyllostachys pubescens

Ultrastructural changes in secondary wall formation of Phyllostachys pubescens Mazel fiber were investigated with transmission electron microscopy. Fiber developed initially with the elongation of cells containing ribosomes, mitochondria and Golgi bodies in the dense cytoplasm. During the wall thickening, the number of rough endoplasmic reticulum and Golgi bodies increased apparently. There were two kinds of Golgi vesicles, together with the ones from endoplasmic reticulum formed transport vesicles. Many microtubules were arranged parallel to the long axis of the cell adjacent to the plasmalemma. Along with the further development of fiber, polylamellate structure of the secondary wall appeared, with concurrent agglutination of chromatin in the nucleus, swelling and disintegration of organelles, while cortical microtubules were still arranged neatly against the inner side of plasmalemma. Lomasomes could be observed between the wall and plasmalemma. The results indicated that the organelles, such as Golgi bodies together with small vesicles, rough endoplasmic reticulum and lomasomes, played the key role in the thickening and lignification of the secondary wall of bamboo fiber, though cortical microtubules were correlative with the process as well.

Ultrastructural Changes of Scolex on Cysticercus pisiformis during Relative Rest and Motion States

[Objective] This study aimed to research the ultra-morphological changes of scolex of Cysticercus pisiformis during the relative rest and motion states. [Method] The ultrastructure changes of scolex located in cyst and evaginated from cyst after cultivation were comparatively observed by scanning electron microscope. [Result] When the scolex was in the relative rest state, observed from the top, the rostel um with the tegument muscular column that connected to tooth-hook looked like the umbrel a and covered on the front end of the scolex. Viewed from the side of the scolex, the tooth-hook on the rostel um looked like the antler branch and had only one row. Four suckers looked like cavities, and were located in the back of the rostel um and distributed around the scolex in the equidistance. When the scolex was in the motion states, the tegument muscular column on the rostel um contracted, the antler-like tooth-hook extended to periphery, and the sucker also made the ring-like and longitudinal-like contraction. [Conclusion] Ultrastructure of the scolex of C. pisiformis changed apparently during relative rest and motion states. Those changes help scolex to invade the host tissue.

Ultrastructural Studies on the Sieve Elements in Root Protophleom of Arabidopsis thaliana

The ultrastructures of the root protophleom sieve element at different developmental stages of Arabidopsis thaliana L. were investigated using the technique of high pressure freezing and freeze substitution fixing specimen. The results show that in the development of the sieve elements, the nuclei undergo typical characteristics of the programmed cell death (PCD): the nuclear envelopes form emboli, the chromatin condenses and aggregates towards the nuclear envelope, which degrades and fully disappears later. Before the nucleus degradation, neither the nuclear envelope undulation, nucleus lobe nor marked dilation (or bleb) of perinuclear space could be observed. In the cytoplasm of the mature sieve element, there are starch-like granules separately sheathed with a layer of membrane and usually with mitochondria around. These gnanules seem to provide substrates to mitochondria in their function. Small vacuoles originate from endoplasmic reticulum (ER), and no bigger vacuole was found.

Accumulation and ultrastructural distribution of copper in Elsholtzia splendens

Copper accumulation and intracellular distribution in Elsholtzia splendens, a native Chinese Cu-tolerant and accu- mulating plant species, was investigated by transmission electron microscope (TEM) and gradient centrifugation techniques. Copper concentrations in roots, stems and leaves of E. splendens increased with increasing Cu levels in solution. After exposure to 500 μmol/L Cu for 8 d, about 1000 mg/kg Cu were accumulated in the stem and 250 mg/kg Cu in the leaf of E. splendens. At 50 μmol/L Cu, no significant toxicity was observed in the chloroplast and mitochondrion within its leaf cells, but separation appeared at the cytoplasm and the cell wall within the root cells. At >250 μmol/L Cu, both root and leaf organelles in E. splendens were damaged heavily by excessive Cu in vivo. Copper subcellular localization in the plant leaf after 8 days’ exposure to 500 μmol/L Cu using gradient centrifugation techniques was found to be decreased in the order: chloroplast>cell wall>soluble fraction>other organelles. The plant root cell wall was found to be the site of highest Cu localization. Increase of Cu exposure time from 8 d to 16 d, increased slightly Cu concentration in cell wall fraction in roots and leaves, while that in the chloroplast fraction decreased in leaves of the plants grown in both 0.25 μmol/L and 500 μmol/L Cu. TEM confirmed that much more Cu localized in cell walls of E. splendens roots and leaves, but also more Cu localized in E. splendens’ chloroplast when the plant is exposed to Cu levels>250 μmol/L, as compared to those in the plant grown in 0.25 μmol/L Cu. Copper treatment at levels>250 μmol/L caused pronounced damage in the leaf chloroplast and root organelles. Copper localization in cell walls and chloroplasts could mainly account for the high detoxification of Cu in E. splendens.

Ultrastructural Studies on the Development of Oil Cells in Litsea pungens

The developmental process of oil cells in the shoot of Litsea pungens Hemsl. has been studied with transmission electron microscopy. According to the development of the three layers of cell wall, the developmental process could be divided into 4 stages. In stage 1, the cell wall consisted only of a primary (the outmost) cellulose layer, which might further be divided into two substages, the oil cell initial, and the vacuolizing oil cell. During this stage, there were some small electron translucent vesicles and dark osmiophilic droplets of variant sizes in the different-shaped plastids. It was observed that some dark and gray osmiophilic materials coalesced to vacuoles in the cytoplasm. In stage 2, a lamellated suberin layer accumulated inside the primary cellulose layer. In stage 3, a thicker and looser inner cellulose wall layer was formed gradually inside the suberin layer. Some dark osmiophilic droplets have been observed in this loose inner cellulose wall layer. The plasmodesmata were blocked up and became a special structure. Then, the big vacuole, which is the oil sac, was full of osmiophilic oil. In stage 4, the oil cell became matured and the cytoplasm disintegrated. The oil sac enveloped from plasmalemma was attached to the cupule, which was formed by the protuberance of the inner cellulose wall layer into the lumen. After the maturity of oil cell, the ground cytoplasm began to disintegrate and became electron opaque or exhibited in a disordered state, and the osmiophilic oil appeared light gray.

Effects of Weak Light on the Ultrastructural Variations of Phloem Tissues in Source Leaves of Three-Year-Old Nectarine Trees(Prunus persica L.var. nectarina Ait.)

Leaves from three_year_old solar greenhouse nectarine trees ( Prunus persica L. var. nectarina Ait. “Zao Hong Yan”) were used as materials in this study. It was the first time that the ultrastructural characteristics of phloem tissues of source leaves were observed and compared in normal and weak light intensities using the transmission electron microscopy. Results showed that the average diameters of companion cells (CC) and sieve elements (SE) of all kinds of veins were bigger in normal than that in weak light intensity, indicating that light could influence the cell development and growth. Dense cytoplasm with abundant mitochondria, endoplasmic reticulums, multivesicular bodies, vesicles and plastids were observed in normal light intensity. On the contrary, CC with small vacuolar structures and few mitochondrias, endoplasmic reticulums were shown in weak light. Misalignment of grana thylakoid margins of nectarine leaves also was seen in weak light. The sieve pores of SEs were obstructed in weak light. Chloroplasts with numerous starch grains and few mitochondrias were noticed in the mesophyll cell (MES) surrounding the bundle sheath in weak light. The storage of starch grains appeared to result from an unbalance between photosynthate production and export of photosynthates. This observation provided a strong support to the point that most leaves export the most of assimilates in the light time. Plasmodesmal densities between SE/CC, CC/PP (phloem parenchyma cell), PP/PP and PP/BSC (bundle_sheath cell) decreased in weak light. Plasmodesmata were observed between CC/SE (NS) (nacreous_walled sieve element), PP/BSC in branch veins in normal light intensity, but not in weak light. Thus apoplasmic pathway may be the main mode of transport of assimilates in weak light, however symplasmic pathway may be the main mode of transport of assimilates in normal light intensity. These results demonstrated that the solar greenhouse nectarine trees could be adapted to the weak light via the ultrastructure variation of phloem tissues of the source leaves.

Ultrastructural Study on Development of Needle Resin Ducts in Pinus elliottii Engel.

The development of needle resin ducts of Pinus elliottii was studied using electron microscope. The results indicate that the resin duct development encompasses at least three distinctive development stages: the stage of initial cells, the stage of middle lamellae expansion and intercellular space appearance, and the stage of cavity enlargement and the resin duct formation. During the whole development stages, all kinds of organells in the duct cells show different ultrastructural features and regularity, among them the plastids' changing is the most striking one. On the basis of analysing the ultrastructural features of developing resin duct cells, the pattern of duct cavity formation, possible sites of resin synthesis, the manner and way of the resin elimination from the protoplast are discussed.

ULTRASTRUCTURAL OBSERVATIONS ON SPOROGENESIS OF MYXOBOLUS KWANGSIENSIS HSIEH, GONG & XIAO FROM THE KIDNEY OF DACE LABEO ROHITA

The early stages and capsulogenetic stages of sporogenesis of Myxobolus kwangsiensis were studied indetail by electron microscopy. M. kwangsiensis is an intrasellular myxsporen infecting the epithelial cellsof kidney tubules of young dace Labeo rohita. The M. kwangsiensis sporogenesis presents the typical featuresof myxosporea. The initial stages are multinuceate primary cells, with one primary cell typicallyenclosing one secondary cell. The secondary cells are formed directly by cytokinesis inside the primary cells. Theprimary cell participates in the formation of the secondary cell nucleus. The nuclear division of primarycell is asynchronous by amitosis. The parasitic organisms may degenerate inside the epithelial cells at anystage. The modes of sporoblast formation , the typical features of myxosporea and the cause of its degradationare discussed.

Ultrastructural Pathologic Observation on the Gut-Associated Lymphoid Tissues of Sacculus Rotundus of Rabbits Infected with Rabbit Haemorrhagic Disease Virus

Ultrastructural pathological changes in the gut-associated lymphoid tissues of sacculus rotundus (SR) of rabbits infected with rabbit haemorrhagic disease virus (RHDV) were first observed. There were numerous holes at the luminal and basement membrane surfaces of the dome epithelium (DE), consistently accompanied by necrosis of lymphocytes and M-cells, and pronounced depletion of lymphocytes in the domes and follicles, decrease of DE complex with formation of pseudomembranous structure on the surface of the dome epithelium. A specific finding in lymphocytes and macrophages was that severe destruction detraction of the membrane of rough endoplasmic reticulum(RER) was accompanied by conspicious increase of solitary, ribo-some-like particles in the cytoplasm, with appearances of intranuclear particles and intranuclear inclusions. It was found that there were many round and dense virion-like particles, with 26 nm in diameter, in the nuclei and cytoplasm of lymphoctes, plasma cells, macrophages and fibroblasts, or in degenerated cells and cellular debris. At the same time, another round virion-like particles about 34 nm in diameter were also seen in the cytoplasm of some cells and interstitium. The results indicated that the appearances of the ribosome-like particles, virion-like particles and inclusion bodies were related to the replication and assembly of RHDV. The present observations suggested that DE of sacculus rotundus could be a open pathway and a transporting route for the entry of antigens into hosts. While the antigen is profoundly deleterious, DE may be as a closed portal or a barrier preventing the foreign antigenic materials from invading.

Study on the Ultrastructural of Oogenesis of Bullacta exarata

The ultrastructure of oogenesis of Bullacta exarata was studied with transmission electron microscope.The result showed that the oogenesis of Bullacta exarata could be divided into four stages,for example,oogonium,early vitellogenic oocyte,mid vitellogenic oocyte and end vitellogenic oocyte.Besides a large and round nucleus,oogonium mainly contains mitochondria,sacs of golgi and microvillie appears in this stage.At the early stage of vitellogenesis,the organelles are developed,and a great deal of nuages like materials appear in oocyte cytoplasm.At the mid stage of vitellogenesis,the nucleus forms pseudopodia liked extension.The organelles including mitochondria,golgi complex and endoplasmic reticulum are well developed,and lots of yolk granule and lipid droplet are formed in the cytoplasm.The exchange of material between oocytes and follicle cells is intense in this stage.At the end stage of vitellogenesis,the oocytes contain fewer numbers of the organelles.The changes of structure and significance in oocytes,and the exchange of material between oocytes and follicle cells are also discussed.

Ultrastructural Changes of Vegetative Cells in Amaryllis Pollen during Its Germination

Structural and organizational changes of the vegetative cell in Amaryllis vittata Ait. during such dynamic processes of pollen as hydration, activation and germination have been examined with electron microscopy. The mature pollen grain is composed of such organelles as plastids, mitochondria,endoplasmic reticulum, dictyosomes and lipid bodies which are in their resting state. Microfilaments appear as aggregates. After pollen activation, however,the organelles undergo great changes in number and shape: the lamellae of plastids and the cristae of mitochondria increase conspicuously in number, the cisternae of the endoplasmic reticulum become narrower; the dictyosomes produce vesicles actively the lipid bodies become degraded and the microfilament aggregates disperse. Cortical microtubules and spiny vesicles appear in the cytoplasm after germination of the pollen tube. No apparent structural changes of the organelles were noticed any longer during this period and microfilaments are distributed throughout the entire pollen tube as a three-dimensional network.

Ultrastructural Observation of Changes of Polysaccharide Grains in Dormant Shoots of Eucommia ulmoides

Cytochemical and ultrastructural studies indicated that compound spherical bodies observed near the sieve plate in the sieve tube members during the period of cambial dormancy in the shoots of Eucommia ulmoides Oliv. were polysaccharide bodies different from the polysaccharide grains in other parenchyma cells in shoots, and were similar to cell walls in their staining properties. The compound spherical bodies occurred in the sieve elements during the period of cambial rest and disappeared in the sieve elements during the period of cambial quiescence and activity.

Ultrastructural Pathology of Nerve Cells in Mouse Brain Infected with Epidemic B Encephalitis Virus

An animal model of epidemic(Japanese)B encephalitis was estabilisged by injecting theJin Wei Yah 1 stain of B encephalitis virus into the peritoneal cavity of mice.The ultrastructuralchanges of the nerve cells in their brains were studied,special attention being paid to some types ofnerve cell in the cerebellar cortex.The infectet Purkinje cells and especially the granular cells showedspecial and inter,sting pathological features.These were compared with the changes found in the in-fected nerve cells in the cerebral cortex,diencephalon and mesencephalon.A radiating structure consisting of a microveside-microtubule aggregation body at the centerand endoplastic reticulum or virus replication multivesicular structures around it was often found in thein fected nerve cells.Its morphological features were described in detail,and its significance and the se-quenoe of events of its development discussed.In the late stage of infection,virus particles were found in the nuclei of part of the necroticcells.It is considered that they entered the nuclei from the cytoplasm during or after the death of theinfected cells.The observation smade in this study have comfimed in the granular cell of the cerebellum theidea of Chert et al.that the encephalitis B virus particle can he formed in the perinudear cistem ofthe infected nerve cell,and have brought forth further information in this respect.The way of releaseof the virus particles from the infected nerve cells observed in this study is fundamentally consistentwith that observed by Chen et al.but most of the virus particles left the nerve cell via the cell pro-

Ultrastructural changes in non-specific duodenitis

AIM: To investigate the ultrastructural and morphological changes of non-specific duodenitis (NSD) in an attempt to grade them according to the extent of the lesions. METHODS: Biopsies were taken from the mucosa of duodenal bulb of 44 patients selected from the patients undergoing upper gastrointestinal endoscopy for epigastric discomforts. From each patient, two pinch biopsies on the same area were obtained from duodenal bulb. One was for scanning electron microscopy and the other was stained with hematoxylin-eosin, Warthin-Starry silver and both were then examined under light microscope. A total of 12 specimens (three from each degree of the normal and I-III of NSD diagnosed and graded by histology) selected from the 44 patients were dehydrated, critical point dried, coated with gold palladium and examined under a JEOL JSM-30 scanning electron microscope (SEM) at 20 kV. RESULTS: According to the ultrastructural morphologic changes, non-specific duodenitis was divided into normal (as control group), mild, moderate and severe degrees according to results of SEM. The normal villi of duodenal bulb were less than 0.2 mm. There were inflammation cells, occasionally red blood cells and macrophages on the mucosal epithelial surface. Erosion and desquamation of epithelium could be seen. Three cases (25%, 3/12) had gastric metaplasia and Helicobacter pylori(H pylori) infection could be found in 5 cases (41.67%, 5/12) in duodenal bulb mucosa. The most distinctive feature was the ulcer-like defect on the surface of epithelial cells. CONCLUSION: Non-specific duodenitis is a separate entity disease caused by different factors. SEM is of value as an aid in the diagnosis of mucosal diseases of duodenum.

Clinical, cellular, microscopic, and ultrastructural studies of a case of fibrogenesis imperfecta ossium

Fibrogenesis imperfecta ossium is a rare disorder of bone usually characterized by marked osteopenia and associated with variable osteoporosis and osteosclerosis, changing over time. Histological examination shows that newly formed collagen is abnormal, lacking birefringence when examined by polarized light. The case presented demonstrates these features and, in addition, a previously undocumented finding of a persistent marked reduction of the serum C3 and C4. Osteoblasts established in culture from a bone biopsy showed abnormal morphology on electron microscopy and increased proliferation when cultured with benzoylbenzoyl-ATP and 1,25-dihydroxyvitamin D, contrasting with findings in normal osteoblasts in culture. A gene microarray study showed marked upregulation of the messenger RNA(mRNA) for G-protein-coupled receptor 128(GPR 128), an orphan receptor of unknown function and also of osteoprotegerin in the patient's osteoblasts in culture. When normal osteoblasts were cultured with the patient's serum, there was marked upregulation of the mRNA for aquaporin 1. A single pathogenetic factor to account for the features of this disorder has not been defined, but the unique findings described here may facilitate more definitive investigation of the abnormal bone cell function.

DISTRIBUTION AND ULTRASTRUCTURAL LOCALIZATION OF CARCINOEMBRYONIC ANTIGEN (CEA) IN SIGNET RING CELLS OF GASTRIC CANCER

The distribution and ultrastructural localization of CEA in signet-ring cells of 15 gastric cancer specimens were observed by PAP and immunoelectron microscopic methods. The mechanism of abnormal distribution of CEA in the signet-ring cell and its biological significance are discussed. The results showed that the CEA positive rate in signet-ring cells was 100% with the polarity lost in distribution. Under the light microscope, the CEA stain patterns were of two types: cytoplasmic and membranous types. The former was predominant. Under the electron microscope, most of the CEA was distributed on the cell membrane and cytoplasm. CEA was found in intracellular membranous structure of the cancer cells, especially in protein synthesis and transport organellae (RER, Golgi Complex etc.). The synthesis of CEA in cancer cells increased, yet its elimination was somewhat hampered. The result was that the RER became extended and were full of CEA (+) material. In the free signet-ring cell, there was a small and short contact plane. The tight junction was severed as the cell junction reduced. The antigenic determinant of CEA was glycoprotein. The abnormal distribution of CEA in signet-ring cells might be the morphologic reflection of the glycosylation of surface glycoprotein of tumor cells.

A CLINICAL AND ULTRASTRUCTURAL STUDY OF ACUTE ESOINOPHILIC LEUKEMIA

The present study analyses two cases with acute immature eosinophilic leukemia. The clinical, physical, laboratory and pathologic materials are discussed. There is an abnormal number of immature eosinophilic cells in the blood and bone marrow, usually accompanied by anemia and thrombocytopenia. Especially the ultra-structural features include abnormal granules, asynchronous maturation of the nucleus and cytoplasm, dilated endoplasmic reticulum and more conspicuous nucleoli. Differential count was more precise under electron microscope than under light microscope. These findings may be helpful for differential diagnosis and classification.

Characteristics of the Sertoli Cells of Salmonidae from Ohrid Lake during Spermatogenesis-Ultrastructural Analysis

Ultrastructual characteristics of Sertoli cells of Salmonidae from Ohrid Lake during the spermatogenetic cycle have been analysed. Sertoli cells being an integral part of the seminiferous lobules underwent considerable changes, which influenced their cytomorphological features. The degenerative changes of Sertoli cells were manifested by an extreme vacuolisation, mitochondria in degeneration with widened crysts and thickened matrix, desorganised ER, autophagosomes, ＂myeline-like＂ structures and lysed cytoplasmic regions. The above mentioned changes were followed by karyopycnisis, comlete degeneration and delamination of cells from the wall of the seminiferous lobules, lysis and detritus formations （Sertoli necrotic material） in the lumen of the lobules. The aim of this paper is special research of the ultrastructural characteristics, i.e. the changes on a level with testes which happen in the postspawning period in the two species of Teleostei of Ohrid Lake, Ohrid trout （Salmo letnica Kar.） and Ohrid belvica （Acantholingua ochridana Steind.）. The postspawning period is emphasized in Teleostei in this relatively short period, when one reproductive cycle finishes and the following has to start, on a level of testicular parenhyma very important histological changes are going on which give special histological identification, i. e. in the postspawning period there is a complete reorganization of the testes.

Enzymatic and Ultrastructural Studies in a Freshwater Catfish: Impact of Methyl Parathion

Exposure to a sublethal concentration of methyl parathion (MEP) reduced the activity of cytoplasmic malate dehydrogenase. mitochondrial malate dehydrogenase, and lactate dehydrogenase by 30 to 49% in the liver and the skeletal muscle of the freshwater catfish, Clarias batraclms, after 7 days. The activities then began to recover and reached the control levels on the 28th day of MEP exposure. A complete recovery occurred on the 7th day when MEP was withdrawn from the medium after an exposure for 1 week. The withdrawal-dependent recovery in the activities was inhibited partially or completely by actinomycin Dandcycloheximide, suggesting de nova synthesis of the enzymes during the recovery period. A conjoint treatment of MEP and triiodolhyronine (T_3) restored the activities to control levels, indicating T_3 protection against the pesticide toxicity. SDS-PAGE of the cytoplasmic fraction of the liver showed some noticeable changes in the protein pattern after an exposure to MEP. Ultrastructural studies on MEP-treated liver cells showed disappearance of the glycogen granules and appearance of numerous smooth endoplasmic reticulum, lysosomal dense bodies, and swollen mitochondria. These changes in the liver are an indication of hepatic toxicity leading toward necrosis.(c) 1990 Academic Press.Inc.