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Biomedical subjects

C Flügel

Publications and source records attributed to C Flügel.

26 records · Page 2Linked to original sources
PubMed1990

Histochemical differences within the ciliary muscle and its function in accommodation.

During accommodation, the ciliary muscle is known to move forward-inward. This movement depends on the stiffness of the ciliary muscle connections with the scleral spur. These connections are mediated by the tips of the meridional muscle. If the tips are weakened by pharmacological or surgical means, accommodation suffers. For normal accommodation, it is therefore necessary that the tips stiffen before the contraction of the main part of the muscle. We have therefore looked at the primate eye for enzymatic and ultrastructural differences between the tips and the bulk of the muscle viz, the reticular and circular portion. Myosin ATPase was stained after either alkaline or acid preincubation. Lactate dehydrogenase (LDH), succinic dehydrogenase (SDH), NADH-tetrazoliumreductase (TR) and lipids were stained using conventional methods. The results of the enzyme staining were a modest difference between the meridional tips and the bulk. The tips stained stronger for ATPase following both preincubation methods, and for LDH, whereas the bulk cells stained stronger for SDH, NADH-TR and lipids. The tips contained fewer mitochondria and more myofibrils. In all these respects, the tips of the meridional muscle resemble the fast fibers of striated muscle.

Accommodation, Ocular↗
PubMed1990

[Regional differences in the ciliary body of cattle. An electron microscopy and histochemical study].

The bovine ciliary body was investigated by scanning and transmission electron microscopy. The number of cell organelles (mitochondria, rough endoplasmatic reticulum and Golgi complexes) of the nonpigmented (UPE) and the pigmented (PE) epithelium were quantitatively evaluated. Histochemically the activity of carbonic anhydrase (CA) and Na+/K(+)-ATPase was localized within the UPE and PE. As a result of this study, the bovine ciliary body was found to be organized similar to the human and primate ciliary body and can be divided into 4 zones: (1) transition zone between the iris and ciliary body; (2) prelenticular portion of the pars plicata; (3) postlenticular portion of the pars plicata; (4) pars plana. In zone 2 the UPE and PE are filled by numerous mitochondria and show extensive infoldings of the basal cell membranes, which react positively for CA and Na+/K(+)-ATPase, indicating that these cells are involved in the secretion of aequous humor. The transition zone is covered by extremely flat UPE cells and might influence the composition of the aqueous humor by reabsorption rather than secretion. In the postlenticular pars plicata, the number of mitochondria, membrane infoldings and enzyme activity decreases, while the number of rER and Golgi complexes, which are necessary for the synthesis of proteins and proteoglycans, increases. In the pars plana, the UPE is filled completely with filaments pointing to the mechanical strain caused by insertion of the zonular fibers.

Animals↗
PubMed1990

[Structural differences in the structure of the ciliary muscles in eyes of primates. A histochemical and morphological study].

The ciliary muscle of the primate eye was stained histochemically with enzymes used to differentiate fiber types in the skeletal muscle. Differences between the outer meridional section and the rest of the muscle were found with all enzymes. Staining for myosin-ATPase with acid and alkaline preincubation, as well as for lactate dehydrogenase (LDH), resulted in a stronger reaction in the meridional section, while the reticular and circular portions showed minor activities. In contrast, succinate dehydrogenase (SDH) revealed a stronger activity in the reticular and circular muscle cells. Ultrastructurally, the meridional muscle cells contained fewer mitochondria, but more myofibrils in the cytoplasm, while circular and reticular muscle cells showed just the opposite. Therefore, the cells of the meridional ciliary muscle section resemble in some respects the rapid type-II skeletal muscle fibers, and the circular und reticular muscle cells are comparable to the slow type-I fibers of the skeletal muscle.

Animals↗
PubMed1989

Mechanically stripped pigmented and non-pigmented epithelium of the shark ciliary body: morphology and transepithelial electrical properties.

Sections of intact ciliary epithelium and mechanically stripped non-pigmented (NPE) and pigmented (PE) cell layers of adult sharks (Squalus acanthias) were mounted in Ussing-type chambers (area 0.1 cm2). Addition of 10(-5) M forskolin to the aqueous side of intact epithelium significantly increased short-circuit current (Isc) within 15 min and a maximum of approx. 30 microA cm-2 was reached after 45-60 min. Transepithelial potential difference (V) increased from -0.8 mV (aqueous side negative as compared with blood/stromal side) to -1.5 mV, whereas resistance (R) was unchanged (50 omega cm2). Forskolin was without effect when applied to the blood side. In stripped PE preparations (R 15 omega cm2), 10(-5) M forskolin applied to the apical side induced a qualitatively similar change of Isc and V compared with the intact tissue. The forskolin-induced effects were fully reversed by 10(-4) M bumetanide and were not dependent on pretreatment of the tissue with 10(-3) M BaCl2. In stripped NPE preparations resistance was usually less than 10 omega cm2 and was not stable. This is consistent with the morphologic observation that although tight junctions were still demonstrable in stripped NPE cells, the apical membranes were damaged. In preparations taken for light and electron microscopy the stripped PE layer revealed intact epithelial cells. In particular, the basal thirds of the stripped PE cells were in very close contact with each other. These attachment zones may have the appearance of tight junctions. Thus the PE cells of the shark ciliary epithelium can be successfully isolated for transepithelial transport studies. The adenylate cyclase system is present in PE cells, and transepithelial transport of chloride may be regulated by intracellular cAMP.

Animals↗
PubMed1989

Regional differences in the morphology and enzyme distribution of the spiny dogfish (Squalus acanthias) ciliary epithelium.

The ciliary epithelium of spiny dogfish eyes has previously been used for studies of epithelial electrolyte transport and the results are found to be comparable to those obtained in mammals. In this study we report the ultrastructure and enzyme histochemistry of the ciliary epithelium of spiny dogfish in comparison with that of mammals. In contrast to the mammals, the lens in spiny dogfish is connected to the anterior and middle part of the ciliary epithelium by a broad zonula-like suspensory ligament and by a short ligament to the ventral papilla, while the posterior region is mainly free of zonula-like fibers. The non-pigmented epithelium (NPE) of the posterior region shows numerous membrane infoldings, interdigitations and many mitochondria in the cytoplasm as well as histochemical staining for Na+ K(+)-ATPase and carbonic anhydrase (CA). These findings are similar to those seen in the anterior pars plicata of mammals which is mainly involved in aqueous secretion. In the anterior and middle part, the NPE cells have only a few membrane infoldings and few mitochondria in the cytoplasm, but abundant surfaces of rough endoplasmic reticulum, numerous ribosomes and Golgi material, indicating protein synthesis. Histochemically the cells stain for Na+, K(+)-ATPase but not for CA. These findings are comparable to the pars plana in mammals. In contrast to mammals, where the pigmented epithelium (PE) shows nearly no staining for Na+, K(+)-ATPase but an intensive one for CA, the PE cells of spiny dogfish are heavily stained for Na+, K(+)-ATPase in all regions of the eye, but show nearly no staining for CA.

Animals↗
PubMed1988

Presence and distribution of Na+/K+-ATPase in the ciliary epithelium of the rabbit.

Regional differences in the localization of Na+/K+-ATPase in the ciliary epithelium of albino rabbits were studied histochemically using the method of Chayen et al. and ultra-histochemically using a cerium-based method. In addition, the incubation time necessary to achieve first signs of staining was investigated as an indication of Na+/K+-ATPase activity. In the entire pars plicata: prelenticular, postlenticular, as well as tips and valleys, staining was seen in the lateral infoldings of the non pigmented epithelium (NPE) after short incubation periods. Somewhat later, the apical cell membranes also stained. The ultrastructure of these cells, together with the staining pattern, point towards a functional significance of the NPE in active fluid secretion. The pigmented epithelium (PE) did not stain. In the iridial processes and in the area of the ciliary ridges staining first appeared in the apical cell membranes of the NPE, which form the typical ciliary channels. The basolateral infoldings of the NPE also stained, whilst the PE remained unstained. The difference in morphology and staining between pars plicata and iridial processes could indicate a difference in function, e.g. reabsorption of freshly secreted aqueous humour. In the pars plana, only the basolateral infoldings of the PE stained. A functional significance of this area in connection with the blood retina barrier is discussed.

Animals↗
PubMed1988

Histochemical demonstration of carbonic anhydrase and Na+/K+-ATPase in the pecten oculi of the fowl.

The distribution of carbonic anhydrase (CA) and Na+/K+-ATPase was studied histochemically in the pecten of the fowl by light and electron microscopy. No Na+/K+-ATPase activity was seen by the method used here. CA staining was seen in the membranes of the apical and basal microvilli of the endothelial cells, while the cytoplasm took no stain. There were no staining differences between the capillaries of the different regions of the pecten. Only the capillaries of the bridge showed no microvilli and no staining. Neither did arterioles and venules which lacked microvilli stain. The functional significance of the association of CA activity and microvilli is not clear.

Animals↗