Ticks can survive in harsh and fluctuating vegetated environments for long durations between blood feedings with highly developed osmoregulatory mechanisms. Like the unique life history of hematophagous ticks, osmoregulatory organs and their regulatory mechanisms are significantly different from those in the closely related insect taxa. Over the last ten years, research has uncovered several neuropeptidergic innervations of the primary osmoregulatory organ, the salivary glands: myoinhibitory peptide (MIP), SIFamide, and elevenin. These neuropeptides are thought to be modulators of dopamine's autocrine or paracrine actions controlling the salivary glands, including the activation of fluid transport into the lumen of salivary acini and the pumping and gating action of salivary acini for expelling fluids out into salivary ducts. These actions are through two different dopamine receptors, D1 receptor and invertebrate D1-like dopamine receptor, respectively. Interestingly, MIP and SIFamide are also involved in the control of another important excretory/osmoregulatory organ, the hindgut, where SIFamide is myostimulatory, with MIP having antagonistic effects. FGLamide related allatostatin is also found to have axonal projections located on the surface of the rectum. Investigations of the osmoregulatory mechanisms of these critical vector species will potentially lead to the development of a measure to control tick species.

• Keywords
• Dopamine, Neuropeptides, Osmoregulation, Receptors, Tick hindgut, Tick salivary secretion,
• MeSH
• Axons metabolism   ultrastructure   MeSH
• Models, Biological MeSH
• Dopamine metabolism   MeSH
• Endocrine System metabolism   MeSH
• Fluorescent Dyes metabolism   MeSH
• Ixodes metabolism   MeSH
• Neurons metabolism   MeSH
• Organ Specificity * MeSH
• Osmoregulation * MeSH
• Salivary Glands metabolism   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• Dopamine MeSH
• Fluorescent Dyes MeSH

The salivary gland of hard ticks is a highly innervated tissue where multiple intertwined axonal projections enter each individual acini. In the present study, we investigated the ultrastructural architecture of axonal projections within granular salivary gland type II and III acini of Ixodes ricinus female. Using immunogold labeling, we specifically examined the associations of SIFamide neuropeptide, SIFamide receptor (SIFa_R), neuropeptide pigment dispersing factor (PDF), and the invertebrate-specific D1-like dopamine receptor (InvD1L), with acinar cells. In both acini types, SIFamide-positive axons were found to be in direct contact with either basal epithelial cells or a single adlumenal myoepithelial cell in close proximity to the either the acinar duct or its valve, respectively. Accordingly, SIFa_R staining correlated with SIFamide-positive axons in both basal epithelial and myoepithelial cells. Immunoreactivity for both InvD1L and PDF (type II acini exclusively) revealed positive axons radiating along the acinar lumen. These axons were primarily enclosed by the adlumenal myoepithelial cell plasma membrane and interstitial projections of ablumenal epithelial cells. Our study has revealed the detailed ultrastructure of I. ricinus salivary glands, and provides a solid baseline for a comprehensive understanding of the cell-axon interactions and their functions in this essential tick organ.

• MeSH
• Axons metabolism   ultrastructure   MeSH
• Ixodidae MeSH
• Ixodes ultrastructure   MeSH
• Receptors, Dopamine metabolism   MeSH
• Salivary Glands innervation   metabolism   ultrastructure   MeSH
• Microscopy, Electron, Transmission MeSH
• Animals MeSH
• Check Tag
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Receptors, Dopamine MeSH

Granule cells of the human hippocampal dentate gyrus were examined. In controls, granule cells displayed somatic spines and cell nuclei with small infoldings. In addition, the cytoplasm of human granule cells always displayed lipofuscin. Subsurface cisterns of endoplasmic reticulum were frequently observed in the human granule cells. Two types of axosomatic synapses were found; most frequently symmetric and less frequently asymmetric. Many of the axosomatic synapses were isolated by glial processes in tumour or lesion-related epileptic patients, but the ultrastructural characteristics of granule cells were not different from those of the control patients. Large bundles of reactive astroglial fibres appeared regularly in all layers of the dentate gyrus. In tumour infiltrated hippocampi, glial processes dominated the neuropil and the number of perisomatic synapses was markedly reduced. Reduction in the number of perisomatic synapses did not correlate with severity and duration of seizures but did correlate with the malignancy of the tumour. It is suggested that reduction of perisomatic inhibition may not be a characteristic of granule cells in the epileptic human dentate gyrus.

• MeSH
• Axons ultrastructure   MeSH
• Child MeSH
• Adult MeSH
• Epilepsy, Temporal Lobe pathology   MeSH
• Dentate Gyrus cytology   ultrastructure   MeSH
• Hippocampus pathology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Brain Neoplasms pathology   MeSH
• Sclerosis MeSH
• Synapses ultrastructure   MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

In our experimental paradigm we sutured the distal stump of a transected musculocutaneous nerve to an intact ulnar nerve of the rat in an end-to-side fashion. We demonstrated the formation of collateral sprouts from intact afferent and motor axons by application of one type of molecule conjugated by two different fluorophores (Fluoro-Ruby and Fluoro-Emerald). Fluoro-Ruby and Fluoro-Emerald were applied distal to end-to-side suture into fresh cut ends of the ulnar and musculocutaneous nerves, respectively. Formation of collateral sprouts was evidenced by findings of mixed (a yellow to orange color) fluorescence labeling of spinal motoneurons and dorsal root ganglia neurons. Colocalization of two different tracers retrogradely transported to the neurons was verified by the individual green and red fluorescence profiles analyzed by means of the computer-assisted image-analyzing system. Our results unequivocally demonstrate that a nerve stump attached to an intact nerve can induce collateral sprouting of both afferent and motor axons.

• MeSH
• Afferent Pathways anatomy & histology   MeSH
• Axonal Transport physiology   MeSH
• Axons ultrastructure   MeSH
• Fluorescent Dyes MeSH
• Muscle, Skeletal innervation   MeSH
• Rats MeSH
• Motor Neurons cytology   MeSH
• Ulnar Nerve anatomy & histology   MeSH
• Image Processing, Computer-Assisted MeSH
• Rats, Wistar MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Fluorescent Dyes MeSH

Locations of a distinctive mode of trans-endocytosis involving dendrites, axons, and glia were quantified through serial section electron microscopy. Short vesicular or long vermiform evaginations emerged from dendrites and axons and were engulfed by presynaptic or neighboring axons, astrocytes, and, surprisingly, a growth cone to form double-membrane structures called spinules. In total, 254 spinules were evaluated in 326 microm(3) of stratum radiatum in area CA1 of mature rat hippocampus. Spinules emerged from spine heads (62%), necks (24%), axons (13%), dendritic shafts (1%), or nonsynaptic protrusions (<1%) and invaginated into axons (approximately 90%), astrocytic processes (approximately 8%), or a growth cone (approximately 1%). Coated pits occurred on the engulfing membrane at the tips of most spinules (69%), and double-membrane structures occurred freely in axonal and astrocytic cytoplasm, suggesting trans-endocytosis. Spinule locations differed among mushroom and thin spines. For mushroom spines, most (84%) of the spinules were engulfed by presynaptic axons, 16% by neighboring axons, and none by astrocytic processes. At thin spines, only 17% of the spinules were engulfed by presynaptic axons, whereas 67% were engulfed by neighboring axons and 14% by astrocytic processes. Spinules engulfed by astrocytic processes support the growing evidence that perisynaptic glia interact directly with synapses at least on thin spines. Spinules with neighboring axons may provide a mechanism for synaptic competition in the mature brain. Trans-endocytosis of spinules by presynaptic axons suggest retrograde signaling or coordinated remodeling of presynaptic and postsynaptic membranes to remove transient perforations and assemble the postsynaptic density of large synapses on mushroom spines.

• MeSH
• Astrocytes ultrastructure   MeSH
• Axons physiology   ultrastructure   MeSH
• Cytoplasmic Vesicles ultrastructure   MeSH
• Dendrites physiology   ultrastructure   MeSH
• Endocytosis physiology   MeSH
• Hippocampus physiology   ultrastructure   MeSH
• Endoplasmic Reticulum, Smooth ultrastructure   MeSH
• Rats MeSH
• Neuropil ultrastructure   MeSH
• Coated Pits, Cell-Membrane ultrastructure   MeSH
• Rats, Long-Evans MeSH
• Growth Cones ultrastructure   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH

• MeSH
• Axons ultrastructure   MeSH
• Ischemia pathology   MeSH
• Guinea Pigs MeSH
• Nerve Fibers, Myelinated ultrastructure   MeSH
• Sciatic Nerve blood supply   ultrastructure   MeSH
• Organelles ultrastructure   MeSH
• Ranvier's Nodes diagnostic imaging   MeSH
• Ultrasonography MeSH
• Animals MeSH
• Check Tag
• Guinea Pigs MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Peripheral nerve damage is a frequent consequence of trauma, tumor surgery or diseases. Clinical results of functional reinnervation after the application of cutaneous grafts are still unsatisfactory. Differences in the extracellular matrix are considered to be one of the factors responsible for poor results of motor axon reinnervation through the cutaneous graft. To verify these differences, we compared morphological features of the motor axons regenerating through the graft prepared from the saphenous nerve and the motor branch of the femoral nerve. Eighteen female adult rats (Wistar) were used in experiments. The saphenous nerve, the femoral nerve, and its main motor branch were exposed under deep anesthesia with ketamine and xylazine. The nerve graft (10 mm) prepared from the saphenous nerve was applied between the stumps of the transected motor branch of the femoral nerve in the 6 rats. In the next 6 rats, the nerve graft (10 mm) harvested from the motor branch of the femoral nerve was inserted between stumps of the transected motor branch of the femoral nerve on the contralateral side. All rats were perfused with Zamboni's fixative solution 14 days after grafting. The samples of grafts and the intact motor branch (n = 6) were dissected and embedded in Durcupan ACM. Semithin sections stained with Toluidine Blue were used for morphometric analysis of myelinated axons by means of computer-assisted image analysis system. Ultrathin sections counterstained with uranyl acetate were viewed and photographed in an electron microscope. The number of myelinated motor axons showing early regeneration under conditions of the cutaneous and motor nerve grafts was similar. The diameter of axons and thickness of their myelin sheaths were significantly smaller when the axons regenerated into the saphenous nerve in contrast to the motor graft. Morphometric analysis of early regeneration of myelinated motor axons suggests that the cutaneous and motor branches of the femoral nerve provide different conditions not for the growth but for the maturation of motor axons.

• MeSH
• Transplantation, Autologous pathology   physiology   MeSH
• Axons physiology   ultrastructure   MeSH
• Microscopy, Electron MeSH
• Rats MeSH
• Skin innervation   MeSH
• Motor Neurons physiology   ultrastructure   MeSH
• Nerve Fibers, Myelinated physiology   ultrastructure   MeSH
• Tissue and Organ Harvesting methods   MeSH
• Peripheral Nerves physiology   transplantation   ultrastructure   MeSH
• Image Processing, Computer-Assisted MeSH
• Rats, Wistar MeSH
• Nerve Regeneration * MeSH
• Skin Transplantation pathology   physiology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Isolated acellular nerve segments protected from migration of Schwann cells and the acellular nerve segments joined with the distal nerve stumps were prepared by a repeated freeze-thaw procedure in the rat sciatic nerves. The presence of laminin-1 and -2, as well as alpha6 and beta1 integrin chains, was detected by indirect immunohistochemistry in the sections through acellular nerve segments at 7 and 14 days after cryotreatment. The position of basal laminae and Schwann cells was identified by immunostaining for collagen IV and S-100 protein, respectively. The isolated cryo-treated segment without living Schwann cells (S-100-) did not display immunoreactivity for laminins and integrin chains, while the basal lamina position was verified through the whole segment by immunostaining for collagen IV. The absence of immunostaining for laminin-1 and -2 in cryo-treated nerve segment was verified by Western blot analysis. A crucial diminution of laminin-1 and -2 in the cryo-treated nerve segment of 10-mm length did not abolish the growth and maturation of axons. The greater part of nerve segment connected with the nerve stump displayed no immunohistochemical staining for S-100, corresponding with absence of Schwann cells. The border region of the nerve segment contained Schwann cells (S-100+) migrating from the near-freeze undamaged part of the distal nerve stump. In addition to immunostaining for S-100 protein, the migrating Schwann cells displayed immunostaining for laminins (-1, and -2) and integrin chains (alpha6 and beta1). The results indicate that the presence of laminin molecules in the acellular nerve segments prepared by the repeated freeze-thaw procedure is related with the migrating Schwann cells. The immunostaining for laminins and integrin chains, which constitute one of integrin receptor, suggests an autocrine and/or paracrine utilization of laminin molecules in the promotion of Schwann cell migration.

• MeSH
• Axons metabolism   ultrastructure   MeSH
• Integrin alpha6beta1 MeSH
• Integrins metabolism   MeSH
• Rats MeSH
• Laminin metabolism   MeSH
• Peripheral Nerves metabolism   transplantation   ultrastructure   MeSH
• Cell Movement physiology   MeSH
• Rats, Wistar MeSH
• Graft Survival MeSH
• Schwann Cells metabolism   ultrastructure   MeSH
• Brain Tissue Transplantation MeSH
• Freezing MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Integrin alpha6beta1 MeSH
• Integrins MeSH
• Laminin MeSH

Ultrastructure of axosomatic (AS) and axodendritic (AD) synapses in the supraoptic nucleus (NSO) was investigated in a group of normothermic cats and compared with another group of cats after short-term induced hypothermia. Quantitative analysis demonstrated a significant decrease of number of AS synapses, smaller size of AD synaptic knobs, shorter length of the synaptic contact and an increase of the active zone. Evaluation of the shape of the synaptic cleft demonstrated an increase of both positive (P) and negative (N) types in hypothermic animals. The observed morphological changes can be ascribed to the decreased synaptic activity in a greater part of the synaptic population and to the increased activity in a smaller portion of synapses.

• MeSH
• Axons ultrastructure   MeSH
• Dendrites ultrastructure   MeSH
• Hypothermia pathology   MeSH
• Cats MeSH
• Supraoptic Nucleus ultrastructure   MeSH
• Reference Values MeSH
• Synapses ultrastructure   MeSH
• Animals MeSH
• Check Tag
• Cats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Extensor digitorum longus (EDL) muscles from 2- to 28-day-old rats were grafted into EDL muscles of adult inbred recipients (n = 8). At 1-6 months after the operation, experimental muscles were excised and the ultrastructure and innervation of regenerated muscle spindles was examined. Regenerated muscle spindles (n = 36) in isografted EDL muscles contained 4.3 +/- 0.2 (mean +/- SEM) encapsulated muscle fibres. These "intrafusal" muscle fibres lacked nuclear bag and nuclear chain accumulations, which are characteristic of normal muscle spindles; thus, they rather resembled thin encapsulated extrafusal muscle fibres. In the same sample, myelinated axons were found in 33 (92%) muscle spindles, but no sensory terminals were found. These findings demonstrate that regenerated spindles in isografted EDL muscles were not reinnervated by spindle-specific sensory axons, but exclusively by motor axons. Typical intracapsular motor endplates (MEPs) were found in one third of regenerated spindles examined. Their motor terminals contained accumulated mitochondria and synaptic vesicles. As is characteristic for MEPs, axolemma and sarcolemma were separated by a synaptic cleft about 60 nm wide that contained a basal lamina. The underlying sarcolemma formed either small infoldings or none at all, and the subsynaptic area contained only small subsarcolemmal accumulations of mitochondria. It is apparent that the structures described here as "regenerated muscle spindles" do not perform their normal physiological function as stretch receptors because they lack the sensory innervation. The present results show that regeneration and reinnervation in heterochronous isografts corresponds to that previously described in autotransplanted free muscle grafts. The results also show that, during muscle spindle regeneration, intrafusal satellite cells develop into extrafusal-like muscle fibres, apparently due to their motor innervation.

• MeSH
• Axons ultrastructure   MeSH
• Transplantation, Homologous MeSH
• Muscle, Skeletal innervation   physiology   MeSH
• Rats MeSH
• Motor Neurons physiology   MeSH
• Myelin Sheath ultrastructure   MeSH
• Muscle Spindles physiology   ultrastructure   MeSH
• Neurons, Afferent physiology   MeSH
• Rats, Inbred Lew MeSH
• Nerve Regeneration * MeSH
• Regeneration * MeSH
• Muscle Fibers, Fast-Twitch transplantation   ultrastructure   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH