Histology and histopathology Vol.11, nº 2 (1996)
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- PublicationOpen AccessExpression of cytoskeletal proteins and ATPase activity in bovine femoral artery and vein intima(Murcia : F. Hernández, 1996) Trosheva, M.; Dikranian, K.; Nikolov, Sp.Intima1 cells play an important role in the biology of the vascular wall. Variability in the metabolic activity of intimal smooth muscle cells (SMC), as well as the differential expression of cellular cytoskeletal proteins depend on factors such as degree of differentiation, aging, atherosclerosis, etc. Myosin ATPase activity and cytoskeletal proteins were studied in the intima of bovine femoral arteries and veins of mature animals. In some arteries the intima was thickened and two distinct layers - inner elastic hyperplastic (EHL) and outer, musculo-elastic (MEL) were observed. ATPase activity was well defined in endothelial cells (EC) as well as in SMC. However, differential enzymatic expression was observed in thickened intimas. SMC in the EHL were ATPase negative, while in the MEL they were ATPase positive. Al1 EC and SMC in the «normal» intimas were vimentin positive, desmin and cytokeratin negative. In vessels with thickened intimas, the EHL showed intensive vimentin positivity; in the MEL desmin immunoreactive SMC were numerous as were as those in the media. Vimentin-positive SMC occupied their innermost part. Differences in the expression of ATPase activity and cytoskeletal proteins is discussed in terms of possible migration of media1 SMC andlor morphological modulation observed in vessels with altered vascular walls.
- PublicationOpen AccessThe intracellular origin of the melanosome in pigment cells. A review of ultrastructural data(Murcia : F. Hernández, 1996) Schraerrneyer, U.This paper is a review about the ultrastructural data dealing with the origin of the melanin granules in retina1 pigment epithelial cells, in melanocytes, in the ink gland of cuttle fish, in Kupffer cells of the liver, in neurona1 tissues, in cultured pigment cells. The role and structure of lysosomes in melanogenesis are discussed in a separate chapter. The early steps of melanogenesis are ultrastructurally very heterogeneous, even in the same cell types. With respect to this heterogeneity and the considerably different views on melanosome origin in the literature, the author hypothesizes that pigment cells may use protein matrices originated from different cellular pathways. 1) They may either produce a specific protein matrix and be converted into melanin in the classical way, or 2) altematively, a matrix resulting from lysosomal protein degradation or endocytotic pathways may be used and converted into melanin, as found in fibroblasts transfected with the tyrosinase gen or in Kupffer cells. The very heterogeneous ultrastructure of the polymerizing melanin may be influenced by the amount and sterical availability of tyrosine residues in the protein moieties and the activity of tyrosinase.
- PublicationOpen AccessUse of lectin-probes for correlative histochemical and biochemical assessments of the glycosylation patterns of secretory proteins, including kallikreins, in salivary glands and saliva(Murcia : F. Hernández, 1996) Garrett, J.R.; Proctor, G.B.; Zhang, X.S.; Shori, D.K.; Schulte, B.A.Labelled lectins were used as probes to study the glycosylation and secretion of submandibular glycoproteins not only in sections of fixed glands but also in glandular extracts and in nerve-induced saliva, after electrophoretic separations and immobilization in nitrocellulose membranes. In cats the glycoproteins in sympathetic saliva differed considerably from those in parasympathetic saliva. In sympathetic saliva they were found to originate mainly from striated ducts, to some extent from demilunar cells and to a small extent from acinar cells, whereas in parasympathetic saliva they arose mainly from acinar-cells añd demilunes and only to a small extent from striated ducts. In rat submandibular glands sympathetic stimulation caused extensive depletion of lectin stainable granules from granular tubules. Corresponding strong binding occurred with the same lectins to constituents in saliva that ran between 25 and 35 kD on SDS gel electrophoresis and were shown to contain tissue kallikreins. Their binding patterns suggested that individual kallikreins from the same gland may be glycosylated in different ways. This possibility was tested on five different kallikreins after separation from submandibular extracts by isoelectric focussing. Lectin bindings on slot blot preparations of these kallikreins were tested before and after N-glycosidase F, sialidase or endo-a-Nacetylgalactosaminidase digestions. Results showed that, despite their close genetic and structural similarities, the kallikreins are in fact differently sialylated and fucosylated and the novel finding that some contain Oglycosidically linked side chains as well as the anticipated N-glycosidically linked side chains was revealed. Thus, correlative histochemical and biochemical Offprint requests to: Professor J.R. Garrett, Secretory and Soft Tissue Research Unit, Department of Oral Pathology, The Rayne Institute, KCSMD, 123 Coldharbour Lane, London, SE5 9NU, England assessments of bindings with lectin probes has provided important new information about differences in the glycosylation pattems of individual glycoproteins stored within the same secretory granules.
- PublicationOpen AccessUltrastructural studies on myofibrillogenesis and neogenesis of skeletal muscles after prolonged traction in rabbits(Murcia : F. Hernández, 1996) Sun, J.S.; Hou, S.M.; Hang, Y. S.; Liu, T,K.; Lu, K.S.Little is known about the morphological response of muscle after long term traction. The purpose of this study was to investigate the morphological changes of skeletal muscle during limb lengthening. After application of mini-extraskeletal fixator, the hindlimb of New Zealand white rabbit was osteotomized and then slowly lengthened at the rate of 1 mmlday up to a 20 mm gain in length. The muscles of hindlimbs were perfused and dissected. Morphological studies were performed at electron microscopic level. Transmission electron microscopy revealed foci of microtrauma at the myotendinous junction. The distance between the muscle fibers and tendon parenchyma increased, with numerous primitive mesenchyme-like cells interposed within this gap. The cytoplasmic space of these cells was devoid of myofibril formation at the ends of stretched fibers. Within the satellite near the myotendinous junction myofilament production was observed in various gradations of maturation. It is concluded that myofibrillogenesis with traction neogenesis of skeletal muscle during limb lengthening does exist and occurs mainly near the myotendinous junction. The myotendinous junction in mature skeletal muscle actively participated in the process of limb lengthening.
- PublicationOpen AccessHeterogeneous ulmtrastrucmtuorf em elanosome formation in the goldfish induced by osmotic stress(Murcia : F. Hernández, 1996) Schraerrneyer, U.; Dohms, M.; Rack, M.In this study, melanophore cytodifferentiation in the fins of xanthic goldfish that had been exposed to osmotic stress for 18 days was investigated. It was found that multi-vesicular bodies (MVB) are not the only type of premelanosome. Granules having a homogeneous matrix also function as premelanosomes. The presence of acid phosphatase reaction product inside the melanin granules indicated that these organelles in this animal were also related to lysosomes. DOPA-oxidase of tyrosinase, the key enzyme in melanogenesis, was surprisingly not only detected in melanocytes but also in the Golgi stacks of dermal cells. Due to the mechanisms of premelanosome formation it is evident that cytoplasmic material also serves as substrate for melanogenesis. EDX microanalysis was performed to measure the ionic composition of the melanin granules. After aldehyde fixation the newly-formed melanin granules did not contain Na, but had accumulated Ca.