labeo rohita fingerlings were reared in freshwater and exposed to different concentrations of lead nitrate. after the exposure, one fish was sacrificed from each dose and the gill arches were removed. the ultrastructural changes on the gills of this cyprinid fish were investigated through scanning electron microscope (sem). lead treated gill tissues showed certain marked changes such as uplifti...

A mesoscopic model of a diblock copolymer is used to study the motion of a grain boundary separating two regions of perfectly ordered lamellar structures under an oscillatory but uniform shear flow. The case considered is a grain boundary separating lamellae along the so called parallel orientation (with wavevector parallel to the velocity gradient direction) and along the transverse orientatio...

In order to study the dependence of the dimensions of the respiratory apparatus on body size and to provide a morphometric basis for the analysis of branchial gas exchange function, the gills of 12 specimens of Scyliorhinus stellaris L., weighing 0-58—2-62 kg, were examined morphometrically. The average values and the local variations of the structural parameters determining diffusive gas trans...

Clone A colon carcinoma cells develop fanshaped lamellae and exhibit random migration when plated on laminin, processes that depend on the ligation of the a 6 b 4 integrin. Here, we report that expression of a dominant negative RhoA (N19RhoA) in clone A cells inhibited a 6 b 4-dependent membrane ruffling, lamellae formation, and migration. In contrast, expression of a dominant negative Rac (N17...

Histological changes in gills, liver and kidney were used to evaluate the health of Black-Chinned Tilapia Sarotherodon melanotheron obtained from Bietri Bay in Ebrie Lagoon during February 2008 and January 2009. Several histological alterations were observed in the gills, including proliferation in the epithelium of gill filaments and secondary lamellae, proliferation of mucous cells, cyst at t...

The vertebrate photoreceptor cell contains an elaborate cilium that includes a stack of phototransductive membrane disks. The disk membranes are continually renewed, but how new disks are formed remains poorly understood. Here we used electron microscope tomography to obtain 3D visualization of the nascent disks of rod photoreceptors in three mammalian species, to gain insight into the process ...

The pecten oculi is a structure peculiar to the avian eye. Three morphological types of pecten oculi are recognized: conical type, vaned type and pleated type. The pleated type has been well studied. However, there exists only scanty data on the morphology of the latter two types of pectens. The structure of the vaned type of pecten of the ostrich, Struthio camelus was investigated with light a...

Retinal dystrophies, known in man, dog, mouse, and rat, involve progressive loss of photoreceptor cells with onset during or soon after the developmental period. Functional (electroretinogram), chemical (rhodopsin analyses) and morphological (light and electron microscopy) data obtained in the rat indicated two main processes: (a) overproduction of rhodopsin and an associated abnormal lamellar ...

The effect of age on myelin sheath thickness was determined by an electron microscopic examination of cross sections of the vertical bundles of nerve fibers that pass through primary visual cortex of the rhesus monkey. The tissue was taken from the cortices of young (4-9 years of age) and old (over 24 years of age) monkeys, and the sections were taken at the level of layer 4Cbeta. From the elec...