Horizontal projections of area 17 in Cebus monkeys: metric features, and modular and laminar distribution

Metric features and modular and laminar distribution of intrinsic projections of area 17 were studied in Cebus apella. Anterogradely and retrogradely labeled cell appendages were obtained using both saturated pellets and iontophoretic injections of biocytin into the operculum. Laminar and modular distributions of the labeled processes were analyzed using Nissl counterstaining, and/or cytochrome oxidase and/or NADPH-diaphorase histochemistry. We distinguished three labeled cell types: pyramidal, star pyramidal and stellate cells located in supragranular cortical layers (principally in layers IIIa, IIIb alpha, IIIb beta and IIIc). Three distinct axon terminal morphologies were found i.e., Ia, Ib and II located in granular and supragranular layers. Both complete and partial segregation of group I axon terminals relative to the limits of the blobs of V 1 were found. The results are compatible with recente evidence of incomplete segreagation of visual information flow in V 1 of Old and New World primates.

Ultrastructural changes in the pre- and post-synaptic elements of the neuromus cular junction of the adult albino rat following nerve crush lesion

Using electron microscopy, the morphological changes in the presynaptic and postsynaptic elements [nerve terminal, terminal Schwann cells and the post-synaptic folds] of the neuromuscular junction of the rat, induced by nerve crush lesion, have been investigated. Adult albino rats were used in this study. The sciatic nerve was crushed, and denervated gastrocnemius muscles were dissected at different intervals following the crush lesion. The results were given

Fine structure of the sensory nerve endings of the lower lip mucosa of Cebus apella monkey

The morphology of the sensory nerve endings of lower lip mucosa was studied using transmission electron microscopy. The sensory nerve endings are constituted by several thin terminal axons ranging from O.25 to 1.5 mum, and each one is somrrounded by cytoplasmic processes of lamellar cells. These lamellae measure approximately 0.l5mum in width, and contain rough endoplasmic reticulum, mitochondria, microfilaments, and caveolae. Between the lamellae and the terminal axons and also the adjacent lamella are noted desmosome-type junctions. The terminal axons contain numerous mitochondria and clear vesicles measuring from 30 to 5Onm in diameter. The basal lamina of lamellar processes is generally extense appearing as several electron dense lines, and the interlamellar space is characterized by an amorphous substance and some fine collagen fibrils.

Ultrastructure of the Merkel corpuscles of the lower lip mucosa inferior del mono cebus apella

Se estudió la ultraestructura de los corpúsculos de Merkel en la mucosa del labio inferior del labio de los monos Cebus apella. Las células de Merkel se localizan en la base de la red epitelial adyacente e intimamente asociada con una o dos terminaciones nerviosas intra-epiteliales. Las células de Merkel poseen un núcleo dentado, caracterizado por la concentración de numerosos gránulos denso-teñidos con un rango que varía de 30 a 80 nm de diámetro. Las protrusiones citoplasmáticas de las células de Merkel se extienden en los espacios intercelulares, conteniendo microfilamentos paralelos orientados longitudinalmente. Se observan uniones tipo desmosomas entre el axón terminal y las células de Merkel y queratinocitos adyacentes. El axón terminal muestra la presencia de numerosas mitocondrias y vesículas claras que miden de 30 a 50 nm de diámetro. Nuestros hallazgos sugieren que la protrusión citoplasmática puede servir para detectar el movimiento de queratinocitos adyacentes y también relaciona la capa epitelial con el tejido conectivo de la lámina basal

Ultrastructural dystrophic changes in central sensory synaptic terminals in clarke's nucleus neuropil after neonatal seiatic nerve crush

The present investigation demonstrates the long-term dystrophic changes in primary sensory terminals within Clarke's nucleus of young adult rats [12 weeks of age] whose sciatic nerves were subjected to crush injury at birth. Variable degrees of dystrophic changes were observed in the affected axon terminals. These changes included hyperplasia of neurofilaments, accumulation of electron-dense bodies, clustering of synaptic vesieles, distortion of mitochondria, collections of vesicular profiles and vacuoles and engulfment of some terminals by reactive glial cell processes. Accumulation of dense bodies and replacement of synaptic vesieles by neurofilaments were the most frequent features. In the control specimens of the same animals, dystrophie changes were rarely observed. These dystrophie changes are most probably due to transganglionic atrophy caused by defective axonal transport mechanisms from their hypoplastic perikarya in the dorsal root ganglia. Coupled with future studies on the axonal metabolism, these ultrastructural observations will contribute to the understanding of the alterations in the spinal cord synaptic transmission and of the abnormal sensory symptoms associated with peripheral nerve lesions