What's the difference between perineurium and sheath?
Perineurium
Definition:
(n.) The connective tissue sheath which surrounds a bundle of nerve fibers. See Epineurium, and Neurilemma.
Example Sentences:
(1) Electron microscopic observations of the masseter nerve in the aged cats revealed a disruption of the myelin sheaths and a pronounced increase in collagen fibers in the endoneurium and perineurium.
(2) At four weeks, a perineurium-like sheath surrounded the regenerate and longitudinally oriented Schwann cell columns could be observed throughout the regenerate.
(3) If the alterations involve the inner layers of the perineurium, they are likely to impair its barrier function.
(4) The permeability properties of the perineurium in sciatic nerves of 12-week-old rats were studied.
(5) Transperineurial arterioles are defined as any arteriole that is confined to a perineurial cell compartment, which would include all arterioles within the perineurium proper or within perineurial sleeves in the epi- or endoneurium.
(6) This finding is significant in relation to the putative role of the perineurium as a metabolically active perifascicular diffusion barrier that regulates the composition of the endoneurial fluid, as is its possible relevance to the occurrence of endoneurial edema in diabetes.
(7) Perineurial infiltration by lymphocytes and bacillated macrophages was seen to occur through gaps between the constituent cells of a loosened and sometimes proliferated perineurium.
(8) Symptoms occur because adjacent nerve roots are impinged upon by the thin-walled, fluid-filled cysts, which are formed in a space between the endoneurium and the perineurium.
(9) Aminopeptidase N was also observed in connective tissue elements, including the perineurium.
(10) Luminal narrowing and mural thickening of these vessels was compounded by basal laminar thickening of the perineurium.
(11) The perineurium surrounding the olfactory filaments at the superficial submucosal level is only one cell thick.
(12) The calcium phosphate deposits were limited to the outer layers of the perineurium while the innermost lamellae were free.
(13) Peripheral nerves in this animal, as in vertebrates, are covered by endoneurium, perineurium, and epineurium.
(14) The results suggest that the crayfish perineurium is a leaky epithelium capable of a high degree of ion regulation.
(15) The glial cells most affected are those which make up the perineurium.
(16) Type IV cells have long processes which usually become incorporated in bundles containing 2--20 processes, including some cholinergic nerve fibres, and are loosely enveloped by perineurium.
(17) The wall is composed of perineurium and neural tissue.
(18) Large numbers of intact organisms can be seen within the perineurium using electron microscopy, and after extensive sampling a few organisms can be detected within the axon cytoplasm.
(19) It is concluded that M. leprae which are extruded from the circulation into the epineurium (or perineurium) may be carried in inflammatory cells across the perineurium which is loosened and rendered permeable to inflammatory cells as a consequence of chronic inflammation in the adjacent epineurium.
(20) A critical evaluation of the various methods of nerve suture, followed by the description of a new personal method of "mixed suture" taking up the neurolemma and the perineurium in the same stitch.
Sheath
Definition:
(n.) A case for the reception of a sword, hunting knife, or other long and slender instrument; a scabbard.
(n.) Any sheathlike covering, organ, or part.
(n.) The base of a leaf when sheathing or investing a stem or branch, as in grasses.
(n.) One of the elytra of an insect.
Example Sentences:
(1) The oral nerve endings of the palate, the buccal mucosa and the periodontal ligament of the cat canine were characterized by the presence of a cellular envelope which is the final form of the Henle sheath.
(2) Electron microscopic observations of the masseter nerve in the aged cats revealed a disruption of the myelin sheaths and a pronounced increase in collagen fibers in the endoneurium and perineurium.
(3) The authors propose three regular procedures with which they are experienced: repair with a large retromuscular nonabsorbable synthetic tulle prosthesis for extensive epigastric eventrations, fillup aponeuroplasty using the sheath of the rectus abdominis associated with a premuscular patch in case of diastasis or of multiple superimposed orifices and suture associated with a small retromuscular auxiliary patch to treat small incisional hernias.
(4) Extraction tools included flexible, telescoping sheaths advanced over the lead to dilate scar tissue and apply countertraction, deflection catheters, and wire basket snares.
(5) Thirteen soft tissue sarcomas with ultrastructural evidence of nerve sheath differentiation were investigated by immunohistochemistry.
(6) This cell population gives rise initially to oligodendrocytes and then to type-2 astrocytes, both of which apparently collaborate in sheathing axons in the CNS.
(7) Rabbit antirat T-cell serum (ALS(T)) reacted selectively with the surfaces of lymphocytes in the paracortex of lymph node and in the periarteriolar sheath of spleen, and with thymocytes.
(8) After properly fixing the vas deferens with a ring clamp, the surgeon pierces the scrotal skin, vas sheath, and vas deferens in the midline with a curved dissecting clamp held at a 45 degree angle from horizontal.
(9) We immunohistochemically examined the expression of Schwann cell-related markers, nerve growth factor (NGF) receptor, S-100 alpha- and beta-proteins, glial fibrillary acidic protein (GFAP), and galactocerebroside (gal C) in 5 malignant schwannomas, 21 benign peripheral nerve sheath tumors, and 4 apparently normal sural nerves.
(10) The transversalis fascia of the floor of the femoral canal turns down to form the medial wall of the venous compartment of the femoral sheath, and has the support of the curved edge of the lacunar ligament which effectively bars the femoral canal from entering the thigh.
(11) Unique domains of the retinal interphotoreceptor matrix (IPM), termed cone matrix sheaths, are composed largely of chondroitin 6-sulfate proteoglycan in most higher mammalian species.
(12) 2ME treatment caused partial solubilization of the sheaths (45% as determined by amino acid analysis), which could be further improved by combining 2ME with SDS.
(13) The 6.8F ultrasound balloon catheter was placed percutaneously in the right femoral artery through a 9F sheath.
(14) The isolated outer sheath was observed as a triple-layered, closed vesicle carrying a polygonal array by electron microscopy.
(15) These data show that the 515 nm absorbance change is not limited to small closed vesicles like grana, but in the presence of suitable electron donors single lamellae of bundle sheath chloroplasts can also be active.
(16) An outer sheath was isolated from Treponema phagedenis biotype Reiter by our previously developed method (Masuda, K., and Kawata, T. 1982.
(17) Seven tumours were predominantly of blue and spindle-cell, fascicular type, resembling malignant peripheral nerve sheath tumour and at times monophasic synovial sarcoma.
(18) Several additional groups of muscle cells of more limited mass and spatial distribution include the vulval muscles of hermaphrodites, the male sex muscles, the anal-intestinal muscles, and the gonadal sheath of the hermaphrodite.
(19) The notochord, which is composed of a stack of flat cells surrounded by a connective tissue sheath, elongates dramatically and begins straightening between stages 21 and 25.
(20) Under fluoroscopic control a lower polar calix was punctured with 18 G sheathed needle; a guide wire was introduced through the sheet.