Histology and histopathology Vol.11, nº 1 (1996)
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- PublicationOpen AccessFine structure of the pecten oculi of the barred owl (Strix varia)(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 1996) Smith, B. J.; Smith, S. A.; Braekevelt, C. R.The pecten oculi of the barred owl (Strix varia) has been examined by light and transmission electron microscopy. The pecten in this species is of the pleated type and is small in comparison to the size of the ocular globe. The pecten consists of 8-10 accordion-like folds that are linked apically by a pigmented tissue bridge. Each fold contains numerous capillaries, larger supply and drainage vessels, and abundant pleomorphic melanocytes. Most of these capillaries are extremely specialized vessels that possess plentiful microfolds on both the luminal and abluminal surfaces. Some capillaries however display only a few microfolds. The endothelial cell bodies are extremely attenuated, with most organelles located near the nucleus. All capillaries are surrounded by a very thick fibrillar basal lamina, which is thought to provide structural support to these small vessels. Pericytes are commonly found within these thickened basal laminae. Numerous melanocytes are also present, with processes that form an incomplete sheath around the capillaries. These processes are also presumed to provide structural support for the capillaries. As in other avian species, the morphology of the barred owl pecten is indicative of extensive involvement in substance transport. When compared to the pecten of more visually-oriented species, this pecten is smaller, has fewer folds, and displays a reduced number of microfolds within the capillaries. In these and other features, the barred owl pecten is similar to the pecten of the great horned owl (Bubo virginianus).
- PublicationOpen AccessFine structure of the retinal pigment epithelium of the barred owl (Strix varia)(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 1996) Braekevelt, Charlie, R.; Smith, S. A.; Smith, B. J.The retinal pigment epithelium (RPE) as well as the choriocapillaris and Bruch's membrane (complexus basalis) have been studied by light and electron microscopy in the barred owl (Strix varia). The RPE consists of a single layer of cuboidal cells joined laterally by a series of tight junctions that forms part of the blood-ocular barrier. Basally (sclerally) the retinal epithelial cells display numerous deep infoldings while apically (vitreally) microvillar processes interdigitate with the photoreceptor outer segments. Internally the RPE cells show a large vesicular nucleus, plentiful smooth endoplasmic reticulum (SER) and polysomes but very little rough endoplasmic reticulum (RER). Numerous pleomorphic (including ring-shaped) mitochondria are basally located. In the light-adapted state the small melanosomes are almost exclusively located within the apical process indicating that retinomotor movements probably occur. Phagosomes and lysosome-like bodies are present as are myeloid bodies which may show ribosomes on their outer surface. Bruch's membrane is typical of avian species in that it is pentalaminate and the central lamina densa is displaced towards the choroid. The choriocapillaris endothelium is thin but only minimally fenestrated facing Bruch's membrane. Most fenestrations present show a single-layered diaphragm while others display a double-layered diaphragm as noted in other avian species.
- PublicationOpen AccessArgyrophilic nucleolar organizer region (AgNOR) counting in astrocytic gliomas: prognostic value(Murcia : F. Hernández, 1996) Cardesa, Antonio; Ferreres, Joan-Carles; Figols, J.; Val-Bernal, José Fernando; Cruz Sánchez, F.F.In 87 astrocytic gliomas the number of AgNORs/nucleus was retrospectively studied and data correlated with the histological type of the tumors and survival. Al1 patients were treated by the same surgical team and with uniform criteria. Statistically significant differences (p<0.01) were found in relation with the AgNOR averages among the histological types of tumors. A statistically significant linear correlation (p<0.05) between the AgNOR values and survival of the patients was also found. Patients with mean AgNOR values higher than 2.23 and lower than 2.9 survived an average of 11.5I9.1 months vs. a sumival in average of 24.4I34.1 months with mean AgNOR values under 2.23 (p<0.05). Patients with AgNOR values higher than 2.9 survived, on average, 7.7I3.9 months. AgNOR counting in astrocytic gliomas is a reproducible, easy, quick method with prognostic value. AgNORs may be successfully applied in routine material to assess the growth potential of astrocytic gliomas.
- PublicationOpen AccessUltrastructure of liver from piglets fed Tower rapeseed oil(Murcia : F. Hernández, 1996) Cullen, C.; Singh, A.; Shahidi, E.Effect of Tower rapeseed oil (RO) containing lower (0.4%) erucic acid on the piglet liver was studied by electron microscopy. The animals were placed in two groups of four and were fed the diets for eight weeks. Animals in the treated group were given a basal diet comprising corn-soybean plus Tower RO at a 10% concentration; animals that were given the basal diet with no added oil served as the controls. Architecture of the liver from animals of the control group appeared normal. Ultrastructural changes in the liver of RO-fed animals included dilation of lumens and loss of microvilli in bile canaliculi. In addition, closely aligned mitochondrial cristae, elevated number of peroxisomes, and an unusual increase in the size and number of membrane bound spaces in zone 3 of liver acini were noticed. These alterations may reflect a disturbance in piglet liver functions following Tower RO feeding.
- PublicationOpen AccessUltrastructure and organisation of the retina and pigment epithelium in the cutlips minnow, Exoglossum maxillingua (Cyprinidae, Teleostei)(Murcia : F. Hernández, 1996) Collin, S.P.; Collin, H.B.; Ali, M.A.The structure of the light- and dark-adapted retina, pigment epithelium and choriocapillaris of the cutlips minnow, Exoglossum maxillingua (Cyprinidae, Teleostei) is examined by light and electron microscopy. A pronounced vitreal vascularisation overlies the inner retina where the blood vessel walls, the inner limiting membrane and the Müller cell endfeet are al1 closely apposed. The thick Müller cell processes divide the imer plexiform layer and nerve fibre layer into discrete compartments. The ganglion cells do not form fascicles and lie within both the ganglion cell and imer plexiform layers. The inner nuclear layer consists of amacrine, bipolar, Müller cell somata and two rows of horizontal cells. The photoreceptor terminals comprise either multiple (3-5 in cone pedicles) or single (rod spherules) synaptic ribbons. These photoreceptor terminals form either a triad (rods and cones) or a quadrad (cones) mangement of contact with the invaginating processes of the inner nuclear layer cells. The horizontal cell processes of the cone photoreceptor terminals reveal spinule formation in the light-adapted condition. Five photoreceptor types are classified using morphological criteria; triple cones, unequal double cones, large single cones, small single cones and rods. The ratio of rods to cones is approximately 7: 1. Al1 photoreceptor types show retinomotor responses. Only the cones possess accessory outer segments but both rods (8-11) and cones (15-19) possess calycal processes. The retinal pigment epithelium displays retinomotor responses where pigment granules within fine apical processes move vitread to mask the rods in the light. The cells of the retinal pigment epithelium are joined by various types of junctions and contain numerous phagosomes, mitochondria and polysomes. Bruch's membrane or the complexus basalis is trilaminate with two types of collagen fibrils comprising the central layer. The endothelia of the blood vessels of the choriocapillaris, facing Bruch's membrane, are fenestrated. Two to three layers of melanocytes interspersed between large thinwalled capillaries and severa1 layers of collagen fibrils comprise the choriocapillaris.