Ultrastructural changes in the conidia of Penicillium notatum during germination

To study the changes in the cell wall of Penicillium notatum during germination, thin sections of resting, swollen, and germinating spores, and mycelium were compared with thin sections of the isolated cell walls. In the cell wall of resting spores four distinct layers were found. The outermost layer of the cell wall of resting spores was released during swelling and the two inner layers were extended to form the cell wall of the germ tube. The cell wall of young germ tubes had only two layers but a new electron-dense layer was formed later on the outside. Mycelial cell walls which appeared thinner than those of conidia showed three distinct layers. Large mitochondria that divide during germination were present in both resting and swollen spores. Two different types of vacuoles were found, both of which decreased in size and in number during germination. Endoplasmic reticulum was almost absent in resting spores but increased substantially during swelling.

Ultrastructural identification of catecholamine-containing central synaptic terminals

Cytochemical methods for the localization of central catecholamine-containing synaptic terminals have been developed from an extensive foundation of biochemical work and from extrapolation of results on the peripheral sympathetic nervous system. Direct localization of catecholamines in central nerve terminals in some parts of the brain can now be obtained by fixation with permanganates. More broadly applicable, but less direct localizing methods depend upon selective accumulation of tritiated catecholamines for autoradiography or the accumulation of reactive catecholamine congeners which act as markers with conventional fixation. The pattern of acute degenerative changes which result after treatment with 6-hydroxydopamine can also be used to provide an indirect localization of the terminals which had stored catecholamines. When the results of each of the methods are combined, the present techniques indicate that catecholamine-containing terminals in the brain can be identified more confidently than any other system of neurotransmitter substances. Nevertheless, there is considerable need for future cytochemical innovation.

Cephalic structures in the microfilaria of Chandlerella hawkingi

Microfilariae of Chandlerella hawkingi, a filarial parasite of the Indian jungle crow Corvus macrorhynchos Wagler, have been studied using the special staining techniques of Laurence and Simpson (1969). At the tip of the cephalic space a fang-like hook, bifurcated at the base, was visible. Near the hook four equilateral triangle-shaped spines could be seen arranged in a transverse row. There is a well defined oral ring. The pharyngeal thread starts as a funnel-shaped structure to end in the Innenkorper situated in the posterior third of the body.