To develop an animal mode of alcoholic pancreatic steatosis, female Wistar rats were pair fed liquid diets, containing ethanol as 36% of calories or an isocaloric amount of carbohydrate for 3 weeks. Electron microscopic examination showed lipid vesicles localized principally at the bases of pancreatic acinar cells in the ethanol-fed rats. Ethanol feeding significantly increased pancreatic content of cholesteryl ester without changing levels of other lipids. Ethanol feeding enhanced labeled acetate, palmitate, oleate, and linoleate incorporation into cholesteryl ester. Therefore, increased esterification of cholesterol may, in part, explain the observed accumulation of cholesteryl ester.

One eye in each of five adult Wistar hooded rats was covered with opaque contact occluders for three or nine months. The rat retinae were studied with light and electron microscopy. No changes in retinal thickness or in gross structure were seen. However, quantitative differences in synaptic organisation were found.A montage of a normal retina was compared with a similar montage of a three month light-deprived retina. Taking equal areas of inner plexiform layer, the number of amacrine (conventional) synapses i n the light-deprived montage was larger by a factor of about 2.4 relative to the normal one. No significant difference in the number of bipolar (ribbon) synapses was found.( 2 ) Samples were compared from five normal and five light-deprived retinae. The light-deprived retinae showed a significantly larger number of amacrine synapses compared with the normal mean ( p < 0.02).It was not possible to determine if the changes in synaptic number are related to changes in vesicle dimensions reported herein.The increased number of conventional synapses seems evidence that central nervous tissue is capable of forming new synapses without changing the organisation of neural processes.(1) First comparison.Second comparison.The aim of this investigation was to detect with quantitative morphological techniques whether chronic light deprivation can result in structural changes in the rat retina. Since the morphological changes reported herein seem to be limited to the inner plexiforin layer (IPL), the reader is re€erred to Sosula and Glow ('70) for details of the organisation of this layer in the rat.The inner plexiform layer (IPL) in the vertebrate retina was first studied quantitatively by Dowling and Boycott ('65, '66). These investigators showed that the IPL contains amacrine, bipolar, dendritic, and glial processes and analysed the synaptic connectivity of the primate retina.1, Amacrine processes form conventional synapses which resemble Type 2 synapses described by Gray ('59, '61a,b) in the cerebral and cerebellar cortices. Amacrine processes synapse onto the fol-J. COMP. NEUR., 141: 427-452.lowing structures: (1) other amacrine processes; ( 2 ) bipolar processes; ( 3 ) ganglion cell dendrites; ( 4 ) amacrine somata; (5) ganglion cell somata.2. Bipolar processes do not form conventional synapses. A bipolar synapse is characterised by a dense osmiophilic plaque, termed a synaptic ribbon or lamella. At the point where the ribbon lies in the presynaptic bipolar process, two postsynaptic processes are seen. This postsynaptic pair usually consists of an amacrine process and a ganglion cell dendrite -a configuration termed a "dyad by Dowling & Boycott ('65, '66).There seems to be no indisputable evidence in the literature that chronic light deprivation causes morphological changes in retinae of adult animals (Mendelson Ultrastructural studies on the effect of light deprivation on the retina (De Robertis and Franchi, '56; Mountford, '63; Cragg, '69) have been concerned only with the outer plexiform layer (OPL...

A case of sialuria is described in a girl who presented in the neonatal period with hepatosplenomegaly, and who has moderate developmental delay at the age of 2 years. There was massive urinary excretion of free sialic acid (N-acetylneuraminic acid). The clinical, biochemical and ultramicroscopical features were distinct from those described in Salla disease and in infantile sialic acid storage disorder.

The inner plexiform layer (IPL) and adjacent regions of the rat retina were studied by electron microscopy. The IPL contains neural processes of amacrine, bipolar, and ganglion cells, and glial (hluller) processes. Type 1 amacrine processes (maximum diameter 3.1 P ) traced from their somata structurally resemble amacrine perikarya. These processes rarely form synapses. Type 2 amacrine processes (maximum diameter 0.7 p) are radially oriented, forming synaptic expansions e n passant, giving origin to collaterals, also with expansions. The type 2 amacrine processes form conventional synapses onto bipolar, ganglionic and other amacrine processes, onto amacrine and ganglionic somata, and onto dendritic spines. Amacrine perikarya in rare cases contain synaptic vesicles and form somatic synapses onto surrounding processes.Bipolar processes traverse the IPL, forming terminal expansions up to 6 P in diameter near the ganglion somata, which they contact without synaptic vesicle clustering. Bipolar processes form synapses onto dyads. In 73% of dyads, both processes are vesiculated. One process of the dyad pair could usually be identified as an amacrine by its reciprocal synapse back onto the presynaptic bipolar process. The other dyad process, when vesiculated, contains vesicles which are significantly larger and less concentrated than in the adjacent amacrine, and is presumably a ganglion cell dendrite.The ratio of the incidence of amacrine synapses:bipolar synapses is about 8 : l . A subdivision of the IPL into thirds shows that the highest incidence of amacrine synapses is in the middle third. Amacrine somata are significantly larger than bipolar somata. Synaptic vesicles in receptor terminals of the outer plexiform layer are significantly larger and more concentrated than those in axonal processes of the IPL. The functional aspects of these findings are discussed in relation to physiological investigations and interspecies differences described in the literature.Most ultrastructural studies on the retina have been concerned with the outer retinal regions: the rods and cones, and the synapses in the outer plexiform layer (Reviews: Cohen, '63, '69). Mounting interest in the ultrastructural organization of the inner plexiform layer (IPL) has followed the first quantitative studies of Dowling and Boycott ('65, '66) on the primate retina. The recordings from the ganglion cells have shown that processing of visual information occurs between the photoreceptor input and ganglion cell output (De Valois, '66). The activity of the photoreceptor cells is coded for movement, J, COMP. NEUR., 140: 439-478.shape, intensity, and colour before impulses from ganglion cells are relayed to higher centres.The ratio of receptor: bipolar : ganglion cells in the rat retina is approximately 3 6 : 14: 1 (Lashley, '32). The value of the "bipolar cells" in this ratio is probably less than 14, since Lashley ( ' 3 2 ) did not differentiate between amacrine, bipolar, and horizontal cells in the inner nuclear layer. The bipolar cells, however...