scholarly journals Electron Microscope Observations of the Melanocyte of the Human Epidermis

1959 ◽  
Vol 6 (1) ◽  
pp. 41-44 ◽  
Author(s):  
Arwyn Charles ◽  
John T. Ingram
Keyword(s):  
Electron Microscope ◽  
Local Anaesthesia ◽  
Human Epidermis ◽  
Melanin Granule ◽  
Cytoplasmic Matrix ◽  
Pigment Granules ◽  
Human Biopsy

Using standard osmium fixation and methacrylate embedding techniques, a study has been made of the melanocyte of human biopsy skin removed under general and local anaesthesia. Melanogenesis was easily observable in the melanocytes, but immature pigment granules were rarely seen in the Malpighian cells. The passage of melanin from melanocyte to Malpighian cell—cytocrine secretion—is thought to have been observed. Phagocytes near the dermal-epidermal junction seem to have their pigment granules in vacuoles, rather than surrounded directly by the cytoplasmic matrix as in the melanocytes. This, together with the failure to observe "effete" melanocytes, prompts the suggestion that the phagocytes are melanocytes which have migrated from the epidermis into the dermis. A melanin granule is shown with alternating dark and lighter transverse striations, concerning which structure little can at present be said.

scholarly journals SUBMICROSCOPIC CHANGES OF THE SYNAPSE AFTER NERVE SECTION IN THE ACOUSTIC GANGLION OF THE GUINEA PIG. AN ELECTRON MICROSCOPE STUDY

1956 ◽  
Vol 2 (5) ◽  
pp. 503-512 ◽  
Author(s):  
Eduardo De Robertis
Keyword(s):  
Electron Microscope ◽  
Guinea Pig ◽  
Electron Density ◽  
Synaptic Vesicles ◽  
Synaptic Function ◽  
Nerve Section ◽  
Ventral Ganglion ◽  
Intimate Contact ◽  
Cytoplasmic Matrix ◽  
The Matrix

The degenerative changes of the synaptic regions after nerve section have been studied with the electron microscope in the interneuronal synapse of the ventral ganglion of the acoustic nerve of the guinea pig. Fixation with buffered osmic tetroxide was carried out 22, 44, and 48 hours after destruction of the cochlea on one side; the contralateral ganglion being used as control. The submicroscopic organization of normal axosomatic and axodendritic synapses is described. In the synaptic ending four morphological components are recognized: the membrane, the mitochondria, the synaptic vesicles (19, 20), and the cytoplasmic matrix. The intimate contact of glial processes with the endings and with the surface of the nerve cell is described. At the level of the synaptic junction there is a direct contact of the limiting membranes of the ending and of the cell body or dendrite. Both contacting membranes constitute the synaptic one with a total thickness of about 250 A. This membrane has regions of higher electron density where the synaptic vesicles come into intimate contact and fuse with it. Definite degenerative submicroscopic changes in the nerve endings were observed after 22 hours of destruction of the cochlea and were much more conspicuous after 44 and 48 hours. After 22 hours there is swelling of the ending and decreased electron density of the matrix. Most synaptic vesicles have disappeared or seem to undergo a process of clumping and dissolution. Some mitochondria also show signs of degeneration. After 44 hours the synaptic vesicles have practically disappeared; mitochondria are in different stages of lysis; the membrane of the ending becomes irregular in shape, and there is shrinkage and in some cases detachment of the ending. No changes in the postsynaptic cytoplasm were observed. These observations and particularly the rapid lysis of the synaptic vesicles are discussed in correlation with data from the literature indicating the early alteration of synaptic function and the biochemical changes occurring after section of the afferent nerve. The hypothesis that the synaptic vesicles may be carriers of acetylcholine or other active substances (19, 20) and that they may act as biochemical units in synaptic transmission is also discussed.2

scholarly journals THE ERGASTOPLASM

1953 ◽  
Vol 98 (6) ◽  
pp. 607-618 ◽  
Author(s):  
Jules M. Weiss
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Secretory Granules ◽  
Granular Structure ◽  
Ground Substance ◽  
Mitochondrial Membranes ◽  
Cytoplasmic Matrix ◽  
Pancreatic Exocrine ◽  
Exocrine Cell ◽  
Membranous Wall

The fine structure of the ergastoplasm of the pancreatic exocrine cell of Swiss albino mice has been studied with the electron microscope. It was found that this material consists of sac-like structures, which may be called ergastoplasmic sacs, embedded in an amorphous granular ground substance, the cytoplasmic matrix. The membranous wall of the ergastoplasmic sac is a structure approximately 250 A wide. Except for its greater electron density and granular structure, the ergastoplasmic membrane is similar in appearance to the nuclear, plasma, and mitochondrial membranes. From data available in the literature, and from our own evidence, the conclusion can be drawn that the ergastoplasmic membrane contains ribonucleic acid. The mode of formation of the ergastoplasm and secretory granules was studied in animals which were first fasted and subsequently fed. It was found that ergastoplasm is formed within the cytoplasm, near the nuclear membrane, and possibly from the plasma membrane. The secretory granules were observed to arise by accumulation of materials within small ergastoplasmic sacs.

scholarly journals SERIAL RECONSTRUCTION OF THE CHARACTERISTIC GRANULE OF THE LANGERHANS CELL

1968 ◽  
Vol 36 (3) ◽  
pp. 595-602 ◽  
Author(s):  
Richard W. Sagebiel ◽  
Thomas H. Reed
Keyword(s):  
Electron Microscope ◽  
Electron Micrographs ◽  
Three Dimensional ◽  
Langerhans Cell ◽  
Human Epidermis ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Three Dimensional Structure ◽  
Three Dimensional Models ◽  
The Many

Three-dimensional models of individual granules in the same Langerhans cell were made after analyzing serial sections of human epidermis in the electron microscope. These models revealed that the granule is made up of a flattened or curved orthogonal net of particles which is bounded externally by a limiting membrane and which may be disc-shaped, cup-shaped, or combinations of both shapes. This variety of shapes accounts for the many configurations of the granule seen in individual electron micrographs. Usually, the granule has a vesicular portion at, or near one margin. This demonstration of the three-dimensional structure of the granule establishes the inaccuracy of previously used descriptive terms, the granule should be called simply the "Langerhans cell granule."

Internal Structure of Avian Melanin Granules: An Electron Microscope Study

1957 ◽  
Vol s3-98 (42) ◽  
pp. 159-162
Author(s):  
J. G. CARR
Keyword(s):  
Electron Microscope ◽  
Internal Structure ◽  
Rhode Island ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Complex Structure ◽  
Melanin Granule ◽  
Separate Particle

The black melanin granule of the Brown Leghorn male is a separate particle of complex structure, differing from the brown granules of the female, chick down, and Rhode Island Red It is feasible to study the granules in the electron microscope directly in the intact feather.

scholarly journals THE ROLE OF MICROTUBULES IN THE MOVEMENT OF PIGMENT GRANULES IN TELEOST MELANOPHORES

1974 ◽  
Vol 61 (3) ◽  
pp. 757-779 ◽  
Author(s):  
Douglas B. Murphy ◽  
Lewis G. Tilney
Keyword(s):  
Endoplasmic Reticulum ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
Nearest Neighbor ◽  
Cytoplasmic Matrix ◽  
Pigment Granules ◽  
Fixed Array ◽  
Nearest Neighbor Distances ◽  
Rule Out

When microtubules in teleost melanophores are disrupted with antimitotic agents, colchicine, high hydrostatic pressure, low temperature, and vinblastine, the alignment and movement of the pigment granules in these cells disappear; during recovery, the return of alignment and movement corresponds in both time and space with the repolymerization of microtubules. Furthermore, analysis of nearest neighbor distances in untreated melanophores reveals that pigment granules are closely associated with microtubules. Other structures such as microfilaments, the endoplasmic reticulum, and the cytoplasmic matrix do not appear to be involved. Thus we conclude that microtubules determine the alignment and are essential for the selective movements of the pigment granules in these cells. Investigations of the mechanism of movement show that microtubules are required for both centrifugal and centripetal migrations and that they do not change in number or location during redistribution of pigment. Our results further indicate that microtubules in melanophores behave as semistable organelles as determined by investigation with colchicine and hydrostatic pressure. These observations and others rule out a push-pull mechanism based on the polymerization and depolymerization of microtubules or one which distinguishes two operationally different sets of microtubules. We propose instead that particles move by sliding along a fixed array of microtubules.

scholarly journals THE RESPONSE OF VENTRAL HORN NEURONS TO AXONAL TRANSECTION

1972 ◽  
Vol 53 (1) ◽  
pp. 24-37 ◽  
Author(s):  
Donald L. Price ◽  
Keith R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Morphological Changes ◽  
Ventral Horn ◽  
Granular Endoplasmic Reticulum ◽  
Neuronal Nucleus ◽  
Axoplasmic Flow ◽  
Cytoplasmic Matrix ◽  
Show Evidence ◽  
Axonal Transection

The morphological changes induced in the frog ventral horn neurons by axonal transection have been studied with the electron microscope. During the first 2 wk after axotomy the neuronal nucleus becomes more translucent and the nucleolus becomes enlarged and less compact. The cisternae of the granular endoplasmic reticulum vesiculate and ribosomes dissociate from membranes. Free ribosomes and polysomes are dispersed in the cytoplasmic matrix. Neurofilaments and neurotubules are increased in number. These structures appear to be important in the regeneration of the axon. It is proposed that neurotubules, neurofilaments, and axoplasmic matrix are synthesized by the free polyribosomes in the chromatolytic neuron. By the fourth postoperative week, the neurons show evidence of recovery. The cytoplasm is filled with profiles of granular endoplasmic reticulum and many intercisternal polysomes. The substances being manufactured by the newly formed granular endoplasmic reticulum are not clearly defined, but probably include elements essential to electrical and chemical conduction of impulses. The significance of these observations in respect to recent studies of axoplasmic flow is discussed.

scholarly journals INTRACELLULAR CHANGES DUE TO NEUTRAL RED AS REVEALED IN THE PANCREAS AND KIDNEY OF THE MOUSE BY THE ELECTRON MICROSCOPE

1955 ◽  
Vol 101 (2) ◽  
pp. 213-224 ◽  
Author(s):  
Jules M. Weiss
Keyword(s):  
Electron Microscope ◽  
Golgi Complex ◽  
Distal Tubule ◽  
Neutral Red ◽  
Zymogen Granules ◽  
High Concentration ◽  
Cytoplasmic Matrix ◽  
Probable Role ◽  
Pancreatic Exocrine ◽  
Intracellular Changes

The effects of sublethal amounts of the cationic dye, neutral red, upon the structure of pancreatic exocrine cells, and upon the mitochondria of renal distal tubule cells, have been studied with the electron microscope. It was found that neutral red is a cytoplasmic toxin which causes reproducible and characteristic changes in the ergastoplasm, the zymogen granules, the mitochondria, and possibly in the Golgi complex. Ergastoplasmic membranes and granules and zymogen granules lose definition and become continuous with the cytoplasmic matrix. Mitochondria lose their internal folds, develop vacuoles which contain a solution of neutral red in high concentration, and form the nidus for the development of sudanophilic, argyrophilic, osmiophilic inclusions which appear in the cytoplasm after neutral red administration. Golgi granules, one of the three elements of the Golgi complex, appear to increase in number and to be scattered more widely through the cytoplasm than is normal. No consistent changes were found in the cell membrane or nucleus. The ability of the mitochondria to concentrate the cation, neutral red, taken with its well known ability to concentrate the cationic Janus dyes and methylene blue, and its probable role in concentrating those cationic dyes which have been used to demonstrate the "vacuome," is interpreted to signify that one of the functions of mitochondria may be to concentrate intracellar cations.

scholarly journals DEGENERATIVE CHANGES IN THE MITOCHONDRIA OF FLIGHT MUSCLE FROM AGING BLOWFLIES

1972 ◽  
Vol 52 (2) ◽  
pp. 465-477 ◽  
Author(s):  
Bertram Sacktor ◽  
Yoshio Shimada
Keyword(s):  
Electron Microscope ◽  
Acid Phosphatase ◽  
Phosphatase Activity ◽  
Acid Phosphatase Activity ◽  
Flight Muscle ◽  
Phormia Regina ◽  
Cytoplasmic Matrix ◽  
Biochemical Function ◽  
Age Dependent ◽  
T System

Mitochondria from flight muscle of aging blowflies, Phormia regina, were examined morphologically and biochemically with the electron microscope. An age-dependent degeneration of the mitochondria that is characterized, in part, by the reorganization of the inner membrane into myelin-like whorls has been found. The concentric rings increase in size and number, eventually replacing the normal cristal conformation. Glycogen rosettes are frequently seen in the center of the whorl and may represent the intrusion into the mitochondria of the glycogen in the cytoplasmic matrix of the muscle. The degenerating mitochondria are not associated with lysosomal activity, as indicated by the absence of acid phosphatase. An intense acid phosphatase activity is noted, however, in the dyad, comprising elements of the T system and sarcoplasmic reticulurn. Cytochrome oxidase is active in the ultrastructurally intact portion of the mitochondrion but activity is not evident in that part of the mitochondrion that has undergone morphological change. Thus, the ultrastructural degradation of the mitochondria is correlated with a decrease in biochemical function. This suggests a correspondence between a decrease in the bioenergetic capacity of the flight muscle and a decline in the ability of the aged insect to fly.

scholarly journals An Electron Microscope Study of the Rat Ovum

1959 ◽  
Vol 5 (2) ◽  
pp. 327-342 ◽  
Author(s):  
J. Roberto Sotelo ◽  
Keith R. Porter
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Germinal Vesicle ◽  
Follicle Cell ◽  
Multivesicular Bodies ◽  
Early Cleavage ◽  
Open Communication ◽  
Cytoplasmic Matrix ◽  
Vesicular Structure ◽  
Usual Form

This paper reports on the fine structure of rat oocytes at stages before ovulation, during maturation, fertilization, and early cleavage. The study includes parallel observations on light and electron microscope preparations with attempted correlations. The follicular cells of the ovarian egg are described as sending long processes through the zona pellucida to the egg surface where they mingle with thin projections from the egg itself. No open communication between follicle cell cytoplasm and egg cytoplasm was observed. During maturation and fertilization both types of processes are withdrawn from the zona. The germinal vesicle and later the pronuclei of the fertilized egg are characterized by numerous large nucleoli. These have the form of thick walled vesicles with diameters as great as 8 to 10 µ. The wall is dense in the EM image and appears to consist in part of small granules. The cytoplasm shows several inclusions including mitochondria of usual form and a Golgi component which has the typical fine structure and the distribution described by earlier light studies. Small dense particles, presumably RNP particles, are distributed throughout the cytoplasmic matrix and show no preference for membranes. The endoplasmic reticulum of the oocyte is represented by a scattering only of vesicles, but begins a more extensive and elaborate development with the onset of segmentation. One inclusion of the ooplasm, similar in size to mitochondria, receives special attention. It is a vesicular structure, containing a large number of small vesicles (10 to 50 mµ in diameter) and frequently a central density or nucleoid. They are referred to as multivesicular bodies. Such bodies are found in small number in the ovarian egg, but increase greatly in number during maturation and fertilization. It appears from the micrographs of eggs in these latter stages that these vesicular bodies break down and liberate their content of small vesicles to the surrounding ooplasm. Comments are provided on the apparent significance of the various observations.

scholarly journals Electron Microscope Studies of the Human Epidermis The Clear Cell of Masson (Dendritic Cell or Melanocyte)

1958 ◽  
Vol 4 (6) ◽  
pp. 679-684 ◽  
Author(s):  
Wallace H. Clark ◽  
Richard G. Hibbs
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Dendritic Cell ◽  
Potassium Permanganate ◽  
Osmium Tetroxide ◽  
Clear Cell ◽  
Human Epidermis ◽  
Intercellular Bridges ◽  
Distinct Cell

The human epidermis has been studied by electron microscopy following osmium tetroxide and potassium permanganate fixation. An anatomically distinct cell in the human epidermis has been demonstrated with features similar to the melanocyte of the hair bulb described by Barnicot, Birbeck and Cuckow (3). It is dendritic in form and does not contain tonofilaments. "Intercellular bridges" are not formed. The mitochondria are larger and more numerous than those of other epidermal cells and the endoplasmic reticulum is more complex. Some of these cells contain melanin but others are melanin-free. The cell has been interpreted as being identical with the dopa-positive, clear cell of Masson (dendritic cell of Bloch or melanocyte). We have found that many membranous structures in the human epidermis are better preserved by permanganate fixation than by osmium tetroxide fixation.

Sign in / Sign up

Export Citation Format

Share Document