ULTRASTRUCTURAL CHARACTERISTICS OF THE NON-EXPANDED AND EXPANDED EXTRA-EMBRYONIC SHELL OF THE HORSESHOE CRAB,LIMULUS POLYPHEMUSL

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

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Permeability of the microcirculation in area postrema of rat

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100103802 ◽

1988 ◽

Vol 46 ◽

pp. 348-349

Author(s):

Shams M. Ghoneim ◽

Frank M. Faraci ◽

Gary L. Baumbach

Keyword(s):

Brain Stem ◽

Area Postrema ◽

Upper Body ◽

Sprague Dawley ◽

Sodium Cacodylate ◽

Acute Hypertension ◽

Sprague Dawley Rats ◽

Ultrastructural Characteristics ◽

The Brain ◽

Adjacent Brain

The area postrema is a circumventricular organ in the brain stem and is one of the regions in the brain that lacks a fully functional blood-brain barrier. Recently, we found that disruption of the microcirculation during acute hypertension is greater in area postrema than in the adjacent brain stem. In contrast, hyperosmolar disruption of the microcirculation is greater in brain stem. The objective of this study was to compare ultrastructural characteristics of the microcirculation in area postrema and adjacent brain stem.We studied 5 Sprague-Dawley rats. Horseradish peroxidase was injected intravenously and allowed to circulate for 1, 5 or 15 minutes. Following perfusion of the upper body with 2.25% glutaraldehyde in 0.1 M sodium cacodylate, the brain stem was removed, embedded in agar, and chopped into 50-70 μm sections with a TC-Sorvall tissue chopper. Sections of brain stem were incubated for 1 hour in a solution of 3,3' diaminobenzidine tetrahydrochloride (0.05%) in 0.05M Tris buffer with 1% H2O2.

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Human Enamel Replication

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100090889 ◽

1976 ◽

Vol 34 ◽

pp. 180-181

Author(s):

Norman L. Dockum ◽

John G. Dockum

Keyword(s):

Organic Matrix ◽

Human Teeth ◽

Human Enamel ◽

Straight Line ◽

Ultrastructural Characteristics

Ultrastructural characteristics of fractured human enamel and acid-etched enamel were compared using acetate replicas shadowed with platinum and palladium. Shadowed replications of acid-etched surfaces were also obtained by the same method.Enamel from human teeth has a rod structure within which there are crystals of hydroxyapatite contained within a structureless organic matrix composed of keratin. The rods which run at right angles from the dentino-enamel junction are considered to run in a straight line perpendicular to the perimeter of the enamel, however, in many areas these enamel rods overlap, interlacing and intertwining with one another.

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Ultrastructural Characteristics of Platelets Separated from Plasma by ADP-Induced Aggregation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100090804 ◽

1976 ◽

Vol 34 ◽

pp. 164-165

Author(s):

B.A. Shinoda ◽

M.D. Hardison ◽

S.F. Mohammad ◽

H.Y.K. Chuang ◽

R.G. Mason

Keyword(s):

Blood Platelets ◽

Gel Filtration ◽

Differential Centrifugation ◽

Ultrastructural Characteristics ◽

Induced Aggregation

The utilization of blood platelets in experimentation frequently requires their separation from blood and subsequent resuspension in media of known composition. Several methods are available for preparation of isolated platelets (1-3) by differential centrifugation or gel filtration, but most methods are tedious and time consuming. Often platelets obtained by use of such methods are in a state different functionally and ultrastructurally from that of platelets in plasma (4).Recently Mohammad, Reddick, and Mason (5) reported a method in which platelets were separated from plasma by ADP-induced aggregation, washed several times, and then incubated in a carefully selected medium that resulted in deaggregation of platelets.

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SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157838 ◽

1990 ◽

Vol 48 (3) ◽

pp. 58-59

Author(s):

Daryl A. Cornish ◽

George L. Smit

Keyword(s):

Morphological Characteristics ◽

Oreochromis Mossambicus ◽

Breeding Cycle ◽

Limited Information ◽

North West ◽

The North ◽

Sem And Tem ◽

Sperm Development ◽

Ultrastructural Characteristics ◽

The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

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Ultrastructural Classification of Pituary Adenomas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158832 ◽

1990 ◽

Vol 48 (3) ◽

pp. 258-258

Author(s):

S. Arumugam ◽

Sarasa Bharati Arumugam

Keyword(s):

Cytoplasmic Organelle ◽

Null Cell ◽

Cell Adenoma ◽

Mixed Cell ◽

Light Microscope Level ◽

Null Cell Adenoma ◽

Growth Hormone Cell ◽

Ultrastructural Characteristics ◽

Organelle Morphology

Adenoaas of the pituitary are no longer classified based on their tinctorial affinity to dyes. With the advent of the newer methods of sophisticated technology, it is now possible to classify. These depending upon the type of hormone secreted based either on histochemical techniques or on ultrastructural characteristics. The latter provides an insight into the cytoplasmic organelle morphology which offers a delightful feast to the eye as well.This paper presents the ultrastructural characters of the pituitary adenoma as seen in Madras. 171 adenomas (124 males and 47 females) were seen during 1972-1989, classified at the light microscope level as 159 chromophobe, 2 basophilic, 4 eosinophilic and 6 mixed adenomas.Ultrastructural examination showed that the sparsely granular prolactin cell adenoma is the commonest adenoma to be encountered closely followed by the growth hormone cell adenoma, null cell adenoma, the mixed cell adenoma and others.

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