A cytological study of the albuminsecreting cells of the hen oviduct

1. The electron and light microscope have been employed in a cytological study of the albumin-secreting cells of the hen oviduct and of fractions of this tissue obtained after homogenization and differential centrifugation. 2. These studies confirm the observation that in this tissue material corresponding to liver "microsomes" in amino acid-incorporating ability and ribonucleic acid content sediments in relatively low centrifugal fields. 3. The electron microscope studies suggest that the protein secretion of the gland is formed in intimate association with the ergastoplasm.     

THE INFLUENCE OF MAGNETIC FIELDS ON THE PRIMARY HEALING OF INCISIONAL WOUNDS IN RATS

Our studies were conducted to examine the influence of extremely low frequency magnetic fields (ELF-MF) on skin wound healing in male adults rats. We used 40 Hz and 10 mT sinusoidal fields. We evaluated the rate of wound healing by determining the tissue hydroxyproline concentration and scar imaging in electron microscope. The systemic body response to ELF-MF was detected by analysis of blood morphological and biochemical parameters, such as: RBC, WBC, hemoglobin, hematocrit, reticulocytes, electrolytes, urea, and total protein concentration.

ELF-MF induced the increase of hydroxyproline level in scar tissue and intensified the maternity of collagen seen in the electron microscope. The increase of reticulocyte number in blood confirmed that the healing process in experimental animals was supported by the activation of the oxygen supply and utilization processes, as a result of erythropoietic intensification, without simultaneously upsetting cellular energetic processes. We did not obtain changes in biochemical parameters in blood, such as: electrolytes, urea, and total protein concentration, so we concluded that ELF-MF evoked no negative systemic response.     

THE INFLUENCE OF ENVIRONMENT ON THE SHELL STRUCTURE OF STARCH GRANULES

It is well known from light microscope studies of potato starch that the granules formed in a constant environment (of light and temperature) have a ring formation indistinguishable from that of granules formed under field conditions. Electron microscope studies have confirmed that normal potato starch granules have a fine shell structure not usually resolved by the light microscope, and also that shells do not develop in barley granules grown in a constant environment. The paper presented here reports a further study of the dependence of shell formation on environment. Potatoes were grown in a constant environment and starch granules from the newly formed tubers were examined in the light microscope, and in the electron microscope after corrosion by acid. No difference between these granules and normal granules was observed; both wide (light microscope) rings and fine lamellae developed in both granules. Parallel studies were made on wheat starch granules. In this case, shells were not differentiated in granules that developed in a constant environment, but they could be produced at will by imposing a dark period. Thus, shell formation in potato granules must be controlled by an endogenous rhythm, whereas in wheat granules it must be controlled by external environment.     

MORPHOGENESIS OF THE COLLAGENOUS STROMA IN THE CHICK CORNEA

The embryonic chick corneal epithelium produces a highly structured acellular matrix beneath its basal surface during early development. This matrix, which contains collagen, serves as a morphogenetic template for subsequent stromal development in that the three-dimensional architecture of the adult corneal stroma is initially established, in miniature, in this epithelially derived connective tissue. Examination of the early corneal epithelium and matrix in both the light and electron microscope suggests that self assembly of the matrix may be one of several important factors in the morphogenesis of this early connective tissue.     

一种在两栖类胚胎的免疫组织化学研究中有多种用途的方法

本文介绍了我们最近发展的一项用于两栖类胚胎的免疫组织化学研究的技术。两栖类胚胎经过适当的化学固定以后,用振动切片机可以得到50—100 μ的切片。我们用这样的切片进行免疫萤光和免疫酶标染色,均得到满意的结果,可以进行光镜(共聚焦显微镜,普通显微镜)及透射电镜的观察。由于在整个过程中避免了使用有机溶剂及包埋剂,所以最大限度地保存了抗原性。与传统的各种免疫组化技术比较,切片的各部分组织均能迅速与抗体反应,组织保存相当完好,可以满足电镜观察的要求。运用这种方法,还可以将同一胚胎的不同切片分别用于光镜和电镜观察,使结果更具说服力。     

THE LOCATION OF ADENINE NUCLEOTIDE IN THE STRIATED MUSCLE OF THE TOAD

The location of tritiated adenine nucleotide was studied by autoradiography in toad muscle which had been fixed in an acetic acid/ethanol mixture, with lead acetate present to act as the nucleotide precipitant. The muscles were embedded in Araldite. The autoradiographs were examined in both the light microscope and the electron microscope. In confirmation of earlier work, it was found that at least 50 per cent of the adenine nucleotide is concentrated in the I band, near the A-I boundary, and evidence is now available to suggest that this fraction is located in the interfibrillar spaces rather than in the substance of the fibrils. Electron micrographs of unstained sections failed to show any structural features at the site in question, though the triads were made visible by the lead. However, when sections were stained with an alkaline solution containing lead, or with uranyl acetate, "vesicles" were revealed at the appropriate site and it is thought that these may be elements of a transverse network (reticulum) of tubules containing the adenine nucleotide. The location of phosphocreatine could not be investigated because this substance was lost from the muscle during the preparative procedure.     

STRUCTURE OF THE CONCHIOLIN CASES OF THE PRISMS IN MYTILUS EDULIS LINNE

The prisms in the shell of Mytilus edulis Linné are calcite needles. Their small size and their thin conchiolin cases distinguish them from the prisms of many other species of mollusks. These Mytilus prisms have been studied with the electron microscope. The material consisted of positive replicas of surfaces of the prismatic layer, etched with chelating agents, and of preparations of tubular cases from decalcified prisms which were compared with the conchiolin from decalcified mother-of-pearl of the same species. In the replicas, the cases appear as thin pellicles in the intervals between the prism crystals. Both the prism cases and the nacreous conchiolin, disintegrated by exposure to ultrasonic waves and sedimented on supporting films, appear in the form of tightly meshed, reticulated sheets, described as "tight pelecypod pattern" in former studies on nacreous conchiolin of Mytilus. The results show that in the shell of this species the same conchiolin structure is associated with aragonite in mother-of-pearl and with calcite in the prismatic layer.     

A MORPHOMETRIC STUDY ON THE THICKNESS OF THE PULMONARY AIR-BLOOD BARRIER

A reliable knowledge of the thickness of the alveolo-capillary "membrane" or air-blood barrier is of physiologic interest since it is intimately related to a quantitative estimation of such functional events as gas diffusion or tissue metabolism in the lung. The characteristic thickness of the air-blood barrier with respect to gas diffusion is its harmonic mean thickness, while the arithmetic mean thickness is related to the mass of tissue building the barrier and consuming oxygen in the lung. Two morphometric methods are proposed by which these two dimensions can be estimated from random measurements in the electron microscope in a reliable, simple, and efficient manner. By applying these methods to three rat lungs the arithmetic mean thickness of the barrier was found to measure 1.25 µ, the harmonic mean thickness, 0.57 µ. On the basis of these measurements a geometric model of the barrier in the form of a corrugated membrane was derived. Its dimensions showed close similarity to those of the natural barrier. This analysis suggested furthermore that the gas conductance of the barrier is nearly optimal if one considers the mass of tissue and the minimal barrier thickness as fixed properties which are determined by other functional requirements on the alveolo-capillary membrane.     

THE NATURE OF PLASMODESMATA IN NORMAL (LIVING) PLANT TISSUE

Techniques have been devised for the demonstration and study of plasmodesmata in an unaltered state in plant tissues. Text figures and data are presented for plasmodesmata in the cambium and certain other tissues of Pinus strobus, parenchyma tissues of Lycopersicum esculentum, and ray and wood parenchyma tissue of Sequoia sempervirens. In all cases, the plasmodesmata were of similar morphology, with a diameter of approximately 0.2μ. Comparative studies are presented showing the effects of various swelling agents which were used in past studies, and of dehydration which is a normal concomitant of most histological procedures. The present paper provides an important base line for the comparison of the appearance of plasmodesmata in living tissue to the findings of recent studies with the electron microscope.     

THE ULTRASTRUCTURE OF MOUSE LUNG GENERAL ARCHITECTURE OF CAPILLARY AND ALVEOLAR WALLS

The general architecture of capillary and alveolar walls of the mouse lung was studied by means of the electron microscope. In order to minimize tissue damage and to improve the cutting properties of embeddings, several modifications in the tissue processing methods were adopted. These modifications were: fixation by infusion, a prolonged time of dehydration, of impregnation, and of polymerization, the use of acetone for dehydration, ammonium sulfide treatment of the fixed and washed tissue, and an elevated (80°C.) polymerization temperature combined with the use of prepolymerized methacrylate. The generally favorable effects of these modified methods upon preservation and cutting properties of embedded tissue are discussed. Both capillary endothelium and alveolar epithelium were found continuous and without pores. The endothelium was seen to be thinnest in those portions that were adjacent to alveolar air spaces. Two morphological "types" of alveolar epithelial cells were found. One protruded into the alveolar lumen with its thick portion containing the nucleus. The other was often located in a niche of the alveolar wall, and contained peculiar dark inclusions amidst numerous mitochondria. Both were attenuated at their periphery to form the thin epithelial layer. The layer between endothelium and epithelium was designated as basement membrane. It was seen to be generally thin and structureless, but was found thickened in some areas where it also contained collagen fibrils.     

HISTOLOGICAL STAINING OF LIPIDS FOR THE LIGHT AND ELECTRON MICROSCOPE

1. It is generally agreed that the blackening of osmium tetroxide by unsaturated lipid is too unpredictable to demonstrate lipid in tissues.
2. At neutral pH osmium tetroxide combines with the double bonds in the lipoproteins of cellular membranes (mitochondria, etc.) and the deep colour reaction of ethyl gallate with this osmium provides good staining of lipid for the light microscope.
3. Osmium taken up by tissue proteins at neutral pH is only a small fraction of that taken up by the lipid. (After acid fixatives osmium tetroxide is a general protein stain.)
4. The uptake of Sudan black B by partition from dilute solution is a specific test for lipid, but in normally fixed tissue most of the structural lipid is 'bound' and is not accessible to the dye.
5. Cautious treatment of fixed tissue with dilute sodium hypochlorite will unmask this lipid for viewing by the light microscope.
6. Direct fixation with neutral osmium tetroxide is an effective method for visualizing lipid for the electron microscope (as in the ethyl gallate method for the light microscope). But the poor penetration of osmium limits its use in this way.
7. After formol/glutaraldehyde fixation much of the lipid in the tissues is 'bound' and does not take up osmium. It can be unmasked by a saturated aqueous solution of thymol.
8. The unmasked lipid can then be rendered more osmiophil by partition in a solution of the highly unsaturated terpene farnesol, thus increasing the uptake of osmium in a renewed application.
9. Some of the novel observations on tissue lipids made by these methods are reviewed.     

THE EFFECT OF DEPRIVATION OF GLUCOSE ON THE ULTRASTRUCTURE AND FUNCTION OF THE SUPERIOR CERVICAL GANGLION OF THE RAT IN VITRO

The superior cervical sympathetic ganglion of the rat kept in vitro in a bicarbonate-buffered Krebs' solution retains its capacity for synaptic transmission and axonal conduction during more than 36 hr. After glucose withdrawal, synaptic transmission is lost in 2½ hr and this loss is irreversible; on the other hand, axonal conduction can still be measured on the postganglionic nerve for more than 24 hr after glucose deprivation. Electrophysiological measurements as well as electron microscope studies revealed specific changes at the level of the presynaptic terminal processes, while the ganglion cells and the satellite cells remained relatively unaltered. The presynaptic lesion due to lack of glucose can be prevented by keeping the preparation in vitro at 6°C. This strongly suggests that this lesion results from a major disturbance of the metabolism of the presynaptic fibers.     

DEVELOPMENT OF AN IMPROVED MEDIUM FOR THE ISOLATION OF LIVER MITOCHONDRIA

In view of the unsatisfactory appearance, under the electron microscope, of liver mitochondria isolated in isotonic sucrose medium, alternative media have been examined. It was found to be advantageous to replace sucrose by raffinose, and to add levan or, preferably, dextran, together with heparin in suitable concentration. With the optimal medium, the constituents of which are raffinose, versene (optional), dextran of high molecular weight, heparin, and AMP (optional), most of the mitochondria in the osmium-fixed pellet are apparently intact, and show the membranes characteristic of mitochondria as seen in cell sections. The optimal medium has no adverse effect on the activity of the several tissue enzymes which have been studied, except that Mg⁺⁺-activated ATPase is partially inhibited if the medium is present in high concentration in the assay system. Mitochondrial fractions isolated in the new medium have, in common with sucrose fractions, appreciable "free" ATPase activity, this activity being evidently a poor criterion of mitochondrial integrity. Use of the new medium does not decrease the proportion of cytoplasmic ATPase which fails to sediment with the mitochondria, but does give a mitochondrial fraction low in RNA and in acid phosphatase activity and little contaminated with microsomal material. Particles tentatively identified as "lysosomes" have been seen in certain sections.     

THE CHEMICAL NATURE OF KERATOHYALIN GRANULES OF THE EPIDERMIS

Keratohyalin granules were isolated in the native form from the epidermis of newborn rats by the use of citric acid and a detergent. The isolated granules revealed a fine granular substructure in the electron microscope similar to that seen in situ. Analyses of amino acids by automated column-chromatography showed that proline and cystine are present in large proportions whereas histidine is present in a small amount. Accordingly, it was concluded that keratohyalin represents a sulfur-rich amorphous precursor of the horny cell content, rather than a sulfur-poor side product of the keratinization process, or a unique histidine-rich protein as proposed by in situ histochemical and radioautographic studies.     

我国睡莲科花粉形态的研究

本文对我国睡莲科5属11种2变种的花粉形态进行了系统的研究。每种花粉都通过光学显微镜和扫描电镜进行观察和照相。同时对莲和白睡莲二种花粉作了超薄切片,对它们的外型结构进行了透射电镜的观察和照相。并结合有关分类学和孢粉学资料,讨论了本科的原始性、异质性及演化上的问题。     

STUDIES OF THE MITOCHONDRIAL ENERGY-TRANSFER SYSTEM OF BROWN ADIPOSE TISSUE

An investigation of the mechanisms of norepinephrine action and heat production in brown adipose tissue from newborn rabbits has been carried out. Data obtained with the use of biochemical techniques has been correlated with morphological data from electron microscopy. Norepinephrine was found to stimulate the respiration of brown fat in vitro. Inhibitors of glycolysis abolish this effect, whereas inhibitors of oxidative phosphorylation do not, at least not to the same extent. Brown fat is readily permeable to added Krebs cycle intermediates. Substrate level phosphorylation, but no electron transport-coupled phosphorylation, could be demonstrated in isolated mitochondria. It is suggested that the rate of fatty acid oxidation is limited by the availability of phosphate acceptor systems which break down ATP formed at the substrate level and thus provide ADP for further substrate level phosphorylation. The theory of respiratory control by the action of reesterification of fatty acids is discussed in the light of these findings. Under the electron microscope, brown fat mitochondria are characterized by their large size, tightly packed cristae, and by the different types of granules in the matrix. No elementary particles are seen when the mitochondria are examined by the negative-staining technique. The absence of electron transport-coupled phosphorylation together with the apparent absence of elementary particles seems to be of particular significance.     

莼菜(Brasenia schreberi)表皮腺毛细胞高尔基体中一种内含物的初步研究(简报)

在不经过任何特殊处理的常规生物样品中,高尔基体扁囊(Saccules)及囊泡(Vacuoles)中的内含物在电镜下常为低电子密度,而最近我们在莼菜(Brasenia schreberi)叶柄及叶片的表皮腺毛细胞中观察到带有高电子密度的高尔基体内含物。在扁囊中,这些内含物多呈波浪形(图版Ⅰ,图1)。这种特殊形态的高尔基体内含物以及这种未经任何特殊处理而显示出高尔基体中某些物质的现象是前人没有报道过的,本文就这种内含物的结构、性质以及其染色机制进行了初步探讨。