Effect of social isolation on the ultrastructure of the dog brain

Ultrastructural changes in the central nucleus of the amygdalar body, field CA I of the hippocampus, piriform cortex, field 17 and field 7 have been studied in dogs, bred under conditions of social isolation. The changes are more numerous in emotiogenic structures. Similar ultrastructural rearrangements are revealed in the amygdalar body, hippocampus and in both fields of the neocortex. They are: neurons with different degree of chromatolysis, reactive changes in some organelles, terminals with agglutinated vesicles, or with their reduced number, increasing amount of synapses with a short active zone. At the same time, in the piriform gyrus vacuoles, membrane-like and osmiophilic inclusions, terminals with granular vesicles of various size are found more often.     

Effect of hypokinesia on the ultrastructure of emotion-controlling structures in the rat brain

Hypokinesia lasting 40 and 90 days causes a number of ultramicroscopic reorganizations in neurons, synapses and glial elements of the singular cortex and the central amygdaloid nucleus. The longer the time of hypokinesia, the more numerous and variable the reorganizations become. For the amygdaloid body presence of neurons with various degree of chromatolysis, reactive and destructive changes of organells, agglutination and reduction in number of the synaptic vesicles, increasing number of synapses, possessing certain features of low functional activity are most specific. For the singular cortes are peculiar convolution of nuclear and cellular membranes, synaptic contact, increasing intercellular spaces, as well as changes in the structure of some axo-spine synapses, the spine apparatus including.     

Action of high and superhigh doses of fission neutrons and gamma quanta on the central noradrenergic formation of the brain--on the locus coeruleus (the blue spot)

Most of the blue spot neurons of Wistar rats exhibited a pronounced central chromatolysis 24 h following irradiation with fission neutrons (above 100 Gy) and gamma-quanta (above 200 Gy). The changes in the mesencephalic nucleus of the trigeminal nerve were distinct on day 2 after 200 Gy gamma-irradiation. The number of the modified nervous cells in these regions was higher than that in other brain parts.     

Progesterone Effects on Neuronal Ultrastructure and Expression of Microtubule-associated Protein 2 (MAP2) in Rats with Acute Spinal Cord Injury

(1) Following acute spinal cord injury, progesterone modulates several molecules essential for motoneuron function, although the morphological substrates for these effects are unknown. (2) The present study analyzed morphological changes in motoneurons distal to the lesion site from rats with or without progesterone treatment. We employed electron microscopy to study changes in nucleus and cytoplasm and immunohistochemistry for the microtubule-associated protein 2 (MAP2) for changes in cytoskeleton. (3) After spinal cord injury, the nucleoplasm appeared more finely dispersed resulting in reduced electron opacity and the nucleus adopted an eccentric position. Changes of perikarya included dissolution of Nissl bodies and dissociation of polyribosomes (chromatolysis). After progesterone treatment for 3 days, the deafferented motoneurons now presented a clumped nucleoplasm, a better-preserved rough endoplasmic reticulum and absence of chromatolysis. Progesterone partially prevented development of nuclear eccentricity. Whereas 50% of injured motoneurons showed nuclear eccentricity, only 16% presented this phenotype after receiving progesterone. Additionally, injured rats showed reduced immunostaining for MAP2 in dendrites, pointing to cytoskeleton abnormalities, whereas progesterone treatment attenuated the injury-induced loss of MAP2. (4) Our data indicated that progesterone maintained in part neuronal ultrastructure, attenuated chromatolysis, and preclude the loss of MAP2, suggesting a protective effect during the early phases of spinal cord injury.     

SURFACE STRUCTURE OF ISOLATED NEURONS : Detachment of Nerve Terminals during Axon Regeneration

Freehand, isolated neuronal perikarya from the hypoglossal nucleus of the rabbit have been examined with light-and electron-microscopy (transmission and scanning). The surface of the cell bodies was largely covered with spherical particles which were 0.5–2 µ in diameter. Transmission electron microscopy proved that the spherical particles were synaptic nerve terminals. Crush of the hypoglossal nerve which leads to chromatolysis and swelling of the neuronal cell bodies results in a conspicuous reduction in the number of terminals attached to the surface of hypoglossal neurons. This effect was observed both for isolated neurons and in tissue sections. The effect is considered in relation to earlier reported variations in the adherence of neuropil to isolated neuronal perikarya. The functional importance of nerve ending detachment in connection with nerve injury is discussed.     

Chromatolysis in a pair of identifiable metathoracic neurons in the cockroach, Diploptera punctata

The effect of axonal transection upon a specific pair of identifiable nerve cell bodies in the metathoracic ganglion of the cockroach, Diploptera punctata, was studied by electron microscopy. The response of these cells resembles vertebrate chromatolysis in most respects and occurs in two phases : initially, the Golgi bodies decrease in size and the Nissl bodies become more concentrated next to the nucleus and less concentrated in the periphery of the perikaryon; the morphology then changes to one that is more directly concerned with active regeneration of the axon. Autoradiographic experiments showed that the initial changes in basophilia depend primarily upon movement of the Nissl bodies toward the nucleus rather than upon synthesis of new RNA.     

Ultrastructural changes in the septum pellucidum of the cat brain after its long-term self-stimulation

During prolonged electrical stimulation of the septum (self-stimulation 2-3 h daily for 2.5 months) perikarion of most neurons, situated around the tip of the stimulating electrode undergoes peripheral chromatolysis, less part of the neurons is shrunk, mitochondria are desorganized, invaginations of the nuclear membrane occur more often and deeper. Intercellular clefts are sharply dilated, profiles of altered myelin fibers are observed, presynaptic terminals decrease in their number. Axonal terminals with agglutinated vesicles become more numerous. In other terminals osmiophilic bodies and membranous inclusions are revealed. Under electric stimulation a sharp reaction of glial cells, especially astrocytes is observed. One group of astrocytes participate in phagocytosis of the degenerating structures, while the other--in formation of the glial scar.     

Ultrastructural and autoradiographic studies of non-generative cells in the antheridium of Chara vulgaris. I. Manubria

During the development of an antheridium DNA content in manubria gradually increases to 8C-16C level. 3H-thymidine incorporation into the nuclei of the manubria lasts till the stage of quantitative predominance of the 16 celled antheridial filaments. The nucleus of the manubria is characterized by the low content of the condensed chromatin and the presence of nucleoli with the nucleolonema-like structure the number of which increases from 6-8 to 32-38 along with the increase of DNA content in a nucleus. In the cytoplasm of the manubria there are numerous secretive vesicles filled with fine-granular substance discharged outside plasmalemma, active Golgi apparatus, well-developed rough ER, numerous polysomes, mitochondria with the condensed structure and plastids with granar and inter-granar thylakoids as well as plastoglobules which increase in number and size along with the development of the antheridium. During spermiogenesis the cells are vacuolated, the number of the secretive vesicles decreases whereas the electron density of their content increases, smooth ER appears while rough ER is reduced. The manubria actively incorporate 3H-uridine, 3H-tryptophane and 3H-leucine. The increase of the incorporation activity is gradual in the period of increasing polyploidy of the manubria and rapid during the initiation of the spermatozoid differentiation. It has been suggested that the manubria should play an important role in the process of spermatogenesis and the induction of spermatozoid differentiation.     

Correlation of the destructive and reparative processes in neurons of the cerebral cortex in rats after thermal injury

Rat brain sensorimotor cortical neurons were investigated in thermal trauma, using electron microscopic radioautography. RNA synthesis and destructive neuronal changes (chromatolysis, nuclear and mitochondrial damage) have been determined. It has been established that the development of a reparative process--ribosomal RNA synthesis--was roughly parallel to the appearance of destructive changes and was marked in neurons with considerable ultrastructural disturbances.     

Ultrastructure of mitosis inAmoeba proteus

Summary The fine structure ofAmoeba proteus nuclei has been studied during interphase and mitosis. The interphase nucleus is discoidal, the nuclear envelope is provided with a honeycomb layer on the inside. There are numerous nucleoli at the periphery and many chromatin filaments and nuclear helices in the central part of nucleus.In prophase the nucleus becomes spherical, the numerous chromosomes are condensed, and the number of nucleoli decreases. The mitotic apparatus forms inside the nucleus in form of an acentric spindle. In metaphase the nuclear envelope loses its pore complexes and transforms into a system of rough endoplasmic reticulum cisternae (ERC) which separates the mitotic apparatus from the surrounding cytoplasm; the nucleoli and the honeycomb layer disappear completely. In anaphase the half-spindles become conical, and the system of ERC around the mitotic spindle persists. Electron dense material (possibly microtubule organizing centers—MTOCs) appears at the spindle pole regions during this stage. The spindle includes kinetochore microtubules attached to the chromosomes, and non-kinetochore ones which pierce the anaphase plate. In telophase the spindle disappears, the chromosomes decondense, and the nuclear envelope becomes reconstructed from the ERC. At this stage, nucleoli can already be revealed with the light microscope by silver staining; they are visible in ultrathin sections as numerous electron dense bodies at the periphery of the nucleus.The mitotic chromosomes consist of 10 nm fibers and have threelayered kinetochores. Single nuclear helices still occur at early stages of mitosis in the spindle region.     

Observations on neurons and neuroglia from the area of the reticular formation in tissue culture

Summary The area of the reticular formation of the brain stem of several newborn and young manmals was cultivated in vitro. Neurons were observed for a period up to 54 days. At the end of this period in many preparations they still exhibited signs of chromatolysis as judged by the eccentric position of the nuclei and the peripheral location of the Nissl material. It has been impossible thus far to identify particular neurons as belonging to a particular nucleus of the reticular formation, probably due to slight morphological and structural changes of these cells in vitro. Although the oldest neurons observed were kept only 54 days in vitro it seems likely that they could have been maintained for a longer time since their appearance indicated more regenerative rather than degenerative features.Observations on the morphology and kinetics of glial and mesenchymal cells corroborated the findings of Pomerat and Costero (1956) and of Hild (1954, 1957a).This investigation was supported by a research grant (PHS B-364 [C4]) from the National Institute of Neurological Diseases and Blindness, of the National Institutes of Health, Public Health Service, administered by C. M. Pomerat.Fulbright and Smith-Mundt fellow.     

c-fos Expression in Gracilothalamic Tract Neurons after Electrical Stimulation of the Injured Sciatic Nerve in the Adult Rat

The number of c-fos protein-like immunoreactive (Fos-LI) cells in the gracile nucleus was determined after electrical stimulation at Aα/Aβ-fiber strength of the normal and of the previously injured sciatic nerve in adult rats. No Fos-LI cells were seen after electrical stimulation of the noninjured sciatic nerve, or after sciatic nerve injury without electrical stimulation. However, stimulation 21 days after sciatic nerve transection resulted in numerous Fos-LI cells in the ipsilateral gracile nucleus. Combined Fos immunocytochemistry and retrograde labeling from the thalamus showed that the majority (76%; range = 70–80%) of the cells in the gracile nucleus that expressed Fos-LI after nerve injury projected to the thalamus. The results indicate that morphological, biochemical, and physiological alterations in primary sensory central endings and second-order neurons, which have earlier been demonstrated in the dorsal column nuclei after peripheral nerve injury, are accompanied by changes in the c-fos gene activation pattern after stimulation of the injured sciatic nerve. A substantial number of the c-fos-expressing neurons project to the thalamus.     

Relative number and distribution of murine hypothalamic proopiomelanocortin neurons innervating distinct target sites

Proopiomelanocortin (POMC) neurons send projections widely throughout the brain consistent with their role in regulating numerous homeostatic processes and mediating analgesia and reward. Recent data suggest that POMC neurons located in the rostral and caudal extents of the arcuate nucleus of the hypothalamus may mediate selective actions, however it is not clear if POMC neurons in these regions of the arcuate nucleus innervate specific target sites. In the present study, fluorescent microspheres and cholera toxin B were used to retrogradely label POMC neurons in POMC-DsRed transgenic mice. The number and location of POMC cells projecting to the supraoptic nucleus, periaqueductal gray, ventral tegmental area, paraventricular nucleus, lateral hypothalamic nucleus, amygdala and the dosal vagal complex was determined. Tracer injected unilaterally labeled POMC neurons in both sides of the arcuate nucleus. While the total number of retrogradely labeled cells in the arcuate nucleus varied by injection site, less than 10% of POMC neurons were labeled with tracer injected into any target area. Limited target sites appear to be preferentially innervated by POMC neurons that reside in the rostral or caudal extremes of the arcuate nucleus, whereas the majority of target sites are innervated by diffusely distributed POMC neurons. The modest number of cells projecting to each target site indicates that relatively few POMC neurons may mediate potent and specific physiologic responses and therefore disturbed signaling in a very few POMC neurons may have significant consequences.     

Course and termination of the pyramidal tract in the pig

To study the pyramidal tract in the pig, the motor cerebral cortex of one side was defined electrophysiologically and subsequently excised. The animals operated were killed after 7, 11 and 14 days, and the cerebral hemisphere of the operated side, brain stem and spinal cord were removed for histological examination. The pyramidal tract proved to run ipsilaterally as far as the oral extremity of the 12th cranial nerve nucleus. The decussation, which exhausted itself almost completely at the level of the rostral extremity of the 1st cervical metamere, started here. After the limit just mentioned only rare isolated fibres were visible. Along its course, the pyramidal tract sent a small number of axons to the ipsilateral and contralateral nucleus of the 7th cranial nerve, while the fibres running from the opposite side to the reticular formation and to the hypoglossal nerve nucleus, cuneatus, gracilis and trigeminal spinal tract nuclei were more numerous.     

Ultrastructure of the spermatozoid of Lycopodium obscurum (Lycopodiaceae)

Ultrastructural observations reveal that the spermatozoid of Lycopodium obscurum is crescent shaped and contains two posteriorly directed flagella that are inserted at the front of the cell. The nucleus is broad and elongated with a narrow posterior projection or nuclear diverticulum. Spline microtubules (MTs) number 180 at their maximum and provide the framework for the cell. These MTs extend from the anterior of the locomotory apparatus and along the outermost surface of the nucleus, with a central shank of 14–17 MTs encircling the cell for at least one-third gyre beyond the nucleus. The two basal bodies are slightly staggered and positioned at the front of the cell over a highly elongated multilayered structure (MLS). The MLS extends laterally around the cell anterior and curves posteriorly over the nucleus. One large anterior mitochondrion is situated subjacent to the MLS, while numerous small mitochondria are scattered near or among the lobes of the single plastid. The plastid rests on the inner nuclear surface and contains numerous large starch grains. This cell differs from that of L. cernuum, the only other species of Lycopodium examined to date, in that it is more elongated and has an anterior-posterior orientation of the nucleus, basal bodies, MLS, and spline. Comparisons with coiled gametes of bryophytes and Selaginella suggest that some degree of coiling and cell streamlining may be ancestral in archegoniate spermatozoids.     

Inflammatory giant cells: immunophagocytosis and rosette formation

Mouse inflammatory giant cells formed after subcutaneous implantation of coverslips were exposed to sheep red blood cells opsonized with isologous antibodies. The maximal number of engulfed erythrocytes in numerous multinuclear cells exceeded that encountered in subcutaneous macrophages, but, on a per nucleus basis, the giant cells appeared less phagocytic.     

Representation of skeletal muscles in the spinal ganglia of the cat

In 5 experimental and 3 control cats the m. extensor digitorum longus (MEDL) has been extirpated in both extremities. In 10 days the cats are sacrificed with a lethal dose of pentobarbital. In the spinal ganglia, which are supposed to innervate the MEDL, the state of chromatophilic substance is investigated. The amount of neurons with chromatolysis is determined. A new source of the MEDL sensitive innervation--ganglion SIII is revealed. Certain asymmetry in the MEDL ganglia innervation is noted in the left and right sides.     

Brain morphology and immunohistochemical localization of the gonadotropin-releasing hormone in the bluefin tuna, Thunnus thynnus

The present study was focused on the morphology of the diencephalic nuclei (likely involved in reproductive functions) as well as on the distribution of GnRH (gonadotropin-releasing hormone) in the rhinencephalon, telencephalon and the diencephalon of the brain of bluefin tuna (Thunnus thynnus) by means of immunohistochemistry. Bluefin tuna has an encephalization quotient (QE) similar to that of other large pelagic fish. Its brain exhibits well-developed optic tecta and corpus cerebelli. The diencephalic neuron cell bodies involved in reproductive functions are grouped in two main nuclei: the nucleus preopticus-periventricularis and the nucleus lateralis tuberis. The nucleus preopticus-periventricularis consists of the nucleus periventricularis and the nucleus preopticus consisting of a few sparse multipolar neurons in the rostral part and numerous cells closely packed and arranged in several layers in its aboral part. The nucleus lateralis tuberis is located in the ventral-lateral area of the diencephalon and is made up of a number of large multipolar neurones. Four different polyclonal primary antibodies against salmon (s)GnRH, chicken (c)GnRH-II (cGnRH-II 675, cGnRH-II 6) and sea bream (sb)GnRH were employed in the immunohistochemical experiments. No immunoreactive structures were found with anti sbGnRH serum. sGnRH and cGnRH-II antisera revealed immunoreactivity in the perikarya of the olfactory bulbs, preopticus-periventricular nucleus, oculomotor nucleus and midbrain tegmentum. The nucleus lateralis tuberis showed immunostaining only with anti-sGnRH serum. Nerve fibres immunoreactive to cGnRH and sGnRH sera were found in the olfactory bulbs, olfactory nerve and neurohypophysis. The significance of the distribution of the GnRH-immunoreactive neuronal structures is discussed.