The chicken trigeminal ganglion. I. An anatomical analysis of the neuron types in the adult

An anatomical analysis of the chicken trigeminal ganglion was made using light microscopy on specimens prepared by usual chemical fixation or freeze-drying methods and by electron microscopy. Two types of neurons were consistently seen, dark and light cells. Dark cells contained a dense cytoplasm with Nissl substance distributed evenly throughout, whereas light cells had a less dense cytoplasm containing clumps of Nissl substance. The Nissl bodies in light cells contained only a few small cisternae of granular endoplasmic reticulum as compared with many stacked cisternae in Nissl bodies of dark cells. The ratio of dark to light cells was approximately 62:38 in all regions of the ganglion. Dark cells were consistently smaller than light cells. In the seven-day old chick, the mean diameters of the dark and light neurons were 21.4 μ and 29.5 μ respectively; in the adult the values were 29.9 μ and 39.7 μ respectively. It is concluded that the dark and light cells belong to two distinct neuronal cell populations.     

内质网及其标志酶在离体培养脊髓神经元中的发育变化

In an attempt to elucidate the relationship between synapse formation and cell development, the morphology and cytochemistry of the endoplasmic reticulum and its enzymic marker, glucose-6-phosphatase (G-6-Pase), in cultured mouse spinal neurons were investigated ultrastructurally. It was found that in the early period of the development, neurons were characterized by scarceness of organelles; only a few of granular or agranular endoplasmic reticulum and mitochondria were seen. The endoplasmic reticulum and nuclear envelope were packed specifically with G-6-Pase resection product but the product was weak. After a period of culture, most of the neurons had well-developed endoplasmic reticulum, Golgi apparatus, mitochondria and microtubules, etc. The Golgi apparatus was relatively large, having some cisternae associated with vesicles. Either concave of convex face of the saccules was labeled by thiamine pyrophosphatase (TPPase) specifically. GERL, labeled by cytidine monophosphatase (CMPase), was also seen close to the inner or outer face of some Golgi apparatus. The endoplasmic reticulum at this stage was distributed throughout the cytoplasm, including that in dendrites; its enzyme marker (G-6-Pase) localized consistently within the lumen of all endoplasmic reticulum, nuclear space and subsurface cisternae, and frequently in the concave saccules of the Golgi apparatus. After a long-term culture, some neurons became "aged". The endoplasmic reticulum cisternae enlarged and G-6-Pase reaction reduced. Along with the neuronal development, especially maturation of the endoplasmic reticulum and its enzymic marker, synapse formation was begun at the neuropile area. The axo-dendritic synapses always occurred between the axonal terminals and dendrites where the endoplasmic reticulum had showed positive G-6-Pase reactions. Considering the fact, it suggests that the appearance and change of these specific enzymes may be related to the maturation of the neurons in vitro, and also related to the synapse formation between neurons.     

Subcellular reaction to cerebral hypoxia]

Compensatory-adaptive reaction of the brain to hypoxia depends on destructive and reparative processes developing in neuronal and glial elements. A drastic tension and reconstruction of the energy apparatus--mitochondria occurs, as well as reversible disturbances in informative connections between the nucleus and cytoplasm and between nerve fibers and synapses. As a result, structural-functional activity of organells decreases along with changes in metabolic processes. Destructive processes in oligodendroglia, at all stages of the experiment, are more pronounced than in neurons. Preliminary injection of hydroxybutyric acid to the animals preserves the cellular energy potential under hypoxia, that is evident from the lack of severe alterations in mitochondria and other organells. Mechanisms of the adaptive-compensatory reaction in cortical neurons under hypoxia are connected with tension and reconstruction of all organells of the brain cellular elements and with biochemical shifts of lactate dehydrogenase enzymes.     

THE RESPONSE OF VENTRAL HORN NEURONS TO 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.     

Ultrastructural features of the human frontal cortex neurons of maturing and hydrocephalic cerebrum

Human frontal cortex neurons of hydrocephalic infants were studied with electron microscope. A number of maturing neurones exhibited shrinkage and increased electron density of cytoplasmic matrix in the midst of gross hydrocephalic interstitial oedema. Remarkable preservation of growth cones and arrays of microtubules in a few neuronal perikarya and axons were discernible. Rows of normal looking neurones with parallel arrays of cisternae of rough endoplasmic reticulum were also detected. Thus, preservation of significant number of neurones was apparent even in cases of extreme hydrocephalus.     

Light and electron microscopic immunocytochemistry on the localization of 3 beta-hydroxysteroid dehydrogenase/isomerase in the bovine adrenal cortical cells

The localization of 3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta-HSD) was studied in bovine adrenal glands by light as well as electron microscopic immunocytochemistry, using anti-bovine adrenal 3 beta-HSD antibody. With light microscopy the cytoplasm of the glomerulosa cells was weakly immunostained, while that of the fasciculata-reticularis cells was intensely immunostained though both the capsular connective tissue cells and the medullary cells were entirely negative for this reaction. Electron microscopic immunocytochemistry revealed that the positive reaction products for 3 beta-HSD were present on the membrane of smooth endoplasmic reticulum of the cortical cells, especially that of the fasciculata and reticularis cells. Other cell organelles such as mitochondria and Golgi apparatus were entirely negative. The present results indicate that 3 beta-HSD is present in the membrane of smooth endoplasmic reticulum of bovine adrenal cortical cells.     

Destructive and restorative processes of the liver in rats under intensive physical loading

The ultrastructure of rat liver cells after running exercise was investigated. When rats were trained for a month and sacrificed immediately after the last exercise it was revealed that the number of liver cells mitochondria increased, but many of them had alterations: mitochondria became swollen, had lucid matrix. There were some variations in degree of alterations between different mitochondria: a) in the same hepatocyte, b) in different hepatocytes of the same animal, that was connected with individual sensitivity of organelles on the levels of the cell and of the organ. Rough endoplasmic reticulum bore few ribosomes. Glycogen was absent. There were abundant vesicles of smooth endoplasmic reticulum, autophagic vacuoles and peroxisomes in the liver cell cytoplasm. Adaptation of rat liver to the exercise programme becomes evident by 1.5 month of exercise. Mitochondria and rough endoplasmic reticulum were numerous and of normal structure. There were many peroxisomes and glycogen granules in the cytoplasm of hepatocyte. The presence of large autophagic vacuoles in the cytoplasm of some hepatocytes were obviously connected with more rapid destruction of some organelles, than in control.     

HRP-labeled masticatory neurons in the rat trigeminal mesencephalic nucleus: a light and electron microscopic study

The neurons innervating the muscles of mastication were labeled retrogradely with horseradish peroxidase (HRP) which was injected into each muscle of mastication of the rats. The TMB-HRP labeled neurons were for light microscopic and DAB-HRP labeled neurons for electron microscopic study. Many HRP-labeled mesencephalic neurons were observed in the trigeminal mesencephalic nucleus (TMEN) after HRP injection in jaw-closing muscles (JCM). On the other hand, no labeled neurons were found following the application of HRP to the lateral pterygoid and the anterior belly of the digastric muscles, with the exception of a very few from the mylohyoid muscle. The latter three muscles were jaw-opening muscles (JOM). The mesencephalic neurons of each JCM in the TMEN were rather randomly distributed, although they were concentrated more in the caudal region of this nucleus. These neurons were typically unipolar, with spherical to oval perikarya. Each neuron had a single process which coursed caudolaterally to join the mesencephalic tract of the trigeminal nerve. Ultrastructurally, mesencephalic masticatory neurons had a rather regular nucleus locating either centrally or eccentrically in the perikaryon, which is rather plump. The cytoplasm was endowed with very well developed Golgi apparatus and rough endoplasmic reticulum. Neurofilaments, varying in number, intermingled mostly with the Golgi apparatus in the cytoplasm. Somatic spines were frequently observed; however, synapses abutting upon the soma were few. Macula adherens-like structures were occassionally encountered in the contact zone between two cells.     

Neuronal structure of the frog vestibular ganglion]

Neuronal organization of the vestibular ganglion of the nerve VIII in the frog (Rana temporaria) has been studied by means of light and electron microscopy. It has been stated that bipolar ganglion-forming neurons are not quite identical in their structure. They differ in size, fine organization of their cytoplasm and in the manner they construct their glial sheaths. Among ganglial neurons, two types are distinguished: myelinizated and unmyelinizated neurons. A considerable part is composed by neurons coated with myelin sheath which can be constructed according to compact or loose type of myelin. Myelinizated neurons are mostly large cells, with their cytoplasm saturated with organells. Unmyelinizated neurons are coated with a simple sheath composed of one layer of lemmocytes processes. These neurons are much smaller in size, their cytoplasm is poor in organells and contains large amount of neurophilaments.     

Small granule-containing cells of the central nervous system of the bivalve mollusk Patinopectin yessoensis (Jay)

In the CNS of the Patinopecten yessoensis (Jay) two types of cells have been revealed. The I type cells are typical unipolar neurons with a developed granular endoplasmic reticulum and Golgi compex, with a nucleus containing small amount of chromatin. They possess elementary peptidergic granules. The II type cells have in their cytoplasm and processes a large amount of electron-opague granules, specific for adrenergic systems. The nucleus is rich in clustered chromatin, the granular endoplasmic reticulum is poorly developed, cytosomes are absent. According to their ultrastructural organization the latter correspond to small granular cells of the mammalian autonomic nervous system.     

Study on the fine structure of the central nervous system of Pholus labruscoe,L. (Lepidoptera)

Summary This is a preliminary electron microscope investigation in which the structure of insect neurons, neuropile, and interganglionic fibers are studied.Neurons of insect are pear-shaped and have an unique prolongation which ramifies into the neuropile. Their soma is surrounded by glial prolongations that exclude the possibility of nervous contacts. The neuronal cytoplasm is rich in granular material similar to the one described as R.N.A. by several authors; it is scattered at random or associated with endoplasmic reticulum cysternae. The latter does not adopt the regular array characterizing the vertebrate Nissl bodies.A large number of naked fibers is seen in the neuropile. The content of these fibers is different in fibers of different diameter. The thinner elements appear light and show a loose reticular matrix, few vesicles, and mitochondria. The thick fibers are characterized by a denser neuroplasm constituted by a reticular matrix and rows of tiny vesicles alternating with profils of tubuli. In some of these fibers the tubuli are seen in a central position.Three main types of contact relationships between fibers are described in the neuropile. These are; a) cross contacts; b) longitudinal contacts; and c) endknob contacts. The first type is in turn subdivided into subtypes, namely: minimum-area cross contacts and maximum-area cross contacts.A glial sheath enveloping each connective nerve fiber is described. Inside the cytoplasm of such cells there are bundles of dense, thin fibrils twisted along the nerve fibers.The criteria maintained by several authors in regard to the fine structure of the synaptic region are discussed and compared with facts reported in this paper.     

Comparative study of the ultrastructure of immune and normal phytohemagglutinin-treated lymphocytes]

Immune lymphocytes sorbed on the surface of the target cells were characterized during the period of the first three hours of combined incubation by the presence of the electron-dense matrix, abundance of mitochondria and lipids; small lymphocytes had disseminated ribosome organized into polysomes in the medium lymphocytes forming individual cysterns of the granular endoplasmic reticulum in the large lymphocytes, this indicating active protein synthesis by these cells. There were also revealed cells of plasmatic type. Cells incubated with the PHA for one hour represented a homogenous population of small lymphocytes of the same size as the clear cytoplasm containing free ribosomes and individual mitochondria. The proportion of the medium lymphocytes and the blasts increased with increase of the incubation period. These are cells with the clear cytoplasm freely disseminated polyribosomes in which no developed granular endoplasmic reticulum was sometimes revealed. The presence of two types of cells whose ultrastructure reflected their functional characteristics is discussed.     

Ultrastructure of the cell types of the anterior hypophysis in a lizard. I. Corticotrophs

Corticotrophs of the teiid lizard Cnemidophorus lemniscatus are situated in the rostral zone of the pars distalis. In normal animals, they are usually rounded cells with slightly eccentric vesicular nuclei, especially characterized by a lucent hyaloplasm and medium-sized secretory granules of uniform high density. Granules are almost spherical, with small angular deformations, and closely bounded by a fuzzy membrane. Many cells have only a few or a moderate number of granules, with large areas of cytoplasm devoid of them; in others, granules fill the supranuclear region. The cytoplasm exhibits numerous ribosomes, often in rosettes and mostly free, a series of loosely superimposed cisternae of rough endoplasmic reticulum, small dictyosomes, and elongate mitochondria of light matrix. Metyrapone administration during 2-8 days causes dramatic alterations in corticotrophs; they become hypertrophic and extensively degranulated, with a great development of the endoplasmic reticulum and Golgi apparatus, eventually showing a row of large peripheral granules of uneven structure, enclosed in ample vesicles studded with ribosomes. A lesser degree of hypertrophy and degranulation of corticotrophs appears during the first two weeks after thyroidectomy or gonadectomy, and may be partially attributed to surgical stress. Well granulated enlarged corticotrophs, with hypertrophic endoplasmic reticulum and Golgi apparatus, are probably a result of hormonal imbalance in lizards of both sexes gonadectomized for one or two months.     

SUBSURFACE CISTERNS AND THEIR RELATIONSHIP TO THE NEURONAL PLASMA MEMBRANE

Subsurface cisterns (SSC's) are large, flattened, membrane-limited vesicles which are very closely apposed to the inner aspect of the plasma membranes of nerve cell bodies and the proximal parts of their processes. They occur in a variety of vertebrate and invertebrate neurons of both the peripheral and central nervous systems, but not in the surrounding supporting cells. SSC's are sheet-like in configuration, having a luminal depth which may be less than 100 A and a breadth which may be as much as several microns. They are separated from the plasmalemma by a light zone of ~50 to 80 A which sometimes contains a faint intermediate line. Flattened, agranular cisterns resembling SSC's, but structurally distinct from both typical granular endoplasmic reticulum (ER) and from Golgi membranes, also occur deep in the cytoplasm of neurons. It is suggested that membranes which are closely apposed may interact, resulting in alterations in their respective properties. The patches of neuronal plasmalemma associated with subsurface cisterns may, therefore, have special properties because of this association, resulting in a non-uniform neuronal surface. The possible significance of SSC's in relation to neuronal electrophysiology and metabolism is discussed.     

毛竹茎纤维次生壁形成过程的超微结构观察

利用透射电镜观察了毛竹（Ｐｈｙｌｌｏｓｔａｃｈｙｓ ｐｕｂｅｓｃｅｎｓ Ｍａｚｅｌ）茎纤维发育过程中次生壁的形成过程。纤维发育早期,细胞具有较大的细胞核和核仁;细胞质浓稠,具有核糖体、线粒体和高尔基体等细胞器。随着纤维次生壁的形成,细胞壁加厚,细胞质变得稀薄,内质网和高尔基体的数量明显增加,并且两者共同参与了运输小泡的形成;在质膜内侧可观察到大量周质微管分布。随着次生壁的进一步加厚及木质化,细胞壁     

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.     

Evidence for local corticotropin releasing factor (CRF)-immunoreactive neuronal circuits in the paraventricular nucleus of the rat hypothalamus

Summary The interrelationships of corticotropin-releasing factor (CRF) immunoreactive neuronal cell bodies and processes have been examined in the paraventricular nucleus (PVN) of adrenalectomized-dexamethesone treated rats. Antisera generated against ovine CRF (oCRF) were used in the peroxidase-anti-peroxidase-complex (PAP)-immunocytochemical method at both the light and electron microscopic levels. In this experimental model, a great number of CRF-immunoreactive neurons were detected in the parvocellular subdivisions of the PVN and a few scattered labelled parvocellular neurons were also observed within the magnocellular subunits. Characteristic features of immunolabeled perikarya included hypertrophied rough endoplasmic reticulum with dilated endoplasmic cisternae, well developed Golgi complexes and increased numbers of neurosecretory granules. These features are interpreted to indicate accelerated hormone synthesis as a result of adrenalectomy. Afferent fibers communicated with dendrites and somata of CRF-immunoreactive neurons via both symmetrical and asymmetrical synapses. Some neurons exhibited somatic appendages and these structures were also observed to receive synaptic terminals. Within both the PVN and its adjacent neuropil, CRF-immunoreactive axons demonstrated varicosites which contained accumulations of densecore vesicles. CRF-containing axons were observed to branch into axon collaterals. These axons or axon collaterals established axo-somatic synapses on CRF-producing neurons in the parvocellular regions of the PVN, while in the magnocellular area of the nucleus they were found in juxtaposition with unlabeled magnocellular neuronal cell bodies or in synaptic contact with their dendrites. The presence of CRF-immunoreactive material in presynaptic structures suggests that the neurohormone may participate in mechanisms of synaptic transfer.These ultrastructural data indicate that the function of the paraventricular CRF-synthesizing neurons is adrenal steroid hormone dependent. They also provide morphological evidence for the existence of a neuronal ultrashort feedback mechanism within the PVN for the regulation of CRF production and possibly that of other peptide hormones contained within this complex.Supported by NIH grant NS 19266 to WKP     

Role of the endoplasmic reticulum in synaptic transmission

Neurons possess a complex morphology spanning long distances and a large number of subcellular specializations such as presynaptic terminals and dendritic spines. This structural complexity is essential for maintenance of synaptic junctions and associated electrical as well as biochemical signaling events. Given the structural and functional complexity of neurons, neuronal endoplasmic reticulum is emerging as a key regulator of neuronal function, in particular synaptic signaling. Neuronal endoplasmic reticulum mediates calcium signaling, calcium and lipid homeostasis, vesicular trafficking, and proteostasis events that underlie autonomous functions of numerous subcellular compartments. However, based on its geometric complexity spanning the whole neuron, endoplasmic reticulum also integrates the activity of these autonomous compartments across the neuron and coordinates their interactions with the soma. In this article, we review recent work regarding neuronal endoplasmic reticulum function and its relationship to neurotransmission and plasticity.     

Structural changes in the granulosa lutein cells of pregnant cows between 60 and 245 days.

The structural changes in the granulosa lutein cells in the pregnant cows between 60 and 245 days, were observed. The polyhedral or pump cells has an acidophilic cytoplasm around the spherical nucleus. The glycogen granules increased in number up to 230 days of pregnancy. The lipid globules increased in size and amount during advanced pregnancy. The mitochondria showed a wide range of variations in shape and size. The matrix of many mitochondria contained dense inclusions which replaced the entire matrix in late pregnancy. The endoplasmic reticulum was chiefly of smooth type but a few stacks of the rough variety could be seen in the early days of pregnancy. Sometimes, whorls of smooth-surfaced endoplasmic reticulum enclosing mitochondria were seen. The Golgi complex was fully developed in the granulosa cells of all cases studied. The dense granules and lipid globules increased in size and number in the older corpora lutea. The cell surface showed numerous infolding of the plasma membrane.     

牦牛卵泡细胞及其卵母细胞不同发育时期的结构变化

采集成年母牦牛卵巢,通过光镜和电镜对牦牛卵泡及其卵母细胞不同发育时期的结构变化进行了观察。结果发现当卵母细胞被单层立方卵泡细胞包围时,微绒毛开始出现,而皮质颗粒、透明带则在包被2-4层卵泡细胞时开始出现。随着卵母细胞的继续发育,透明带增厚,微绒毛由粗短变为细长,密度增加;皮质颗粒、线粒体、滑面内质网等细胞器的数目不断增加,并逐渐移行到质膜下;在移行的过程中,皮质颗粒成团存在。在囊状卵泡中,卵母细胞皮质颗粒呈线形分布于质膜下,线粒体、滑面内质网又移向胞质中央。卵母细胞借助微绒毛穿过透明带与卵泡细胞胞质突起相联系。结果证明牦牛卵泡和卵母细胞不同发育时期的结构变化与其它哺乳动物的基本相似。