Claes von Mecklenburg

Neuronal localization of dopamine and 5-Hydroxytryptamine in some mollusca

SummaryThe localization of biogenic monoamines in ganglionic tissues from Anodonta piscinalis, Helix pomatia, and Buccinum undatum has been studied by means of the histochemical fluorescence method of Falck and Hillarp.In cerebral, visceral, and pedal ganglia (besides nonfluorescent nerve cells) neurons emitting a green or yellow fluorescence were found. No other cell systems exhibiting a specific fluorescence were observed. An abundance of monoaminergic terminals were found in the central parts of these ganglia. Spectrophotofluorimetric determinations showed that there are large quantities of dopamine and 5-hydroxytryptamine in the tissues investigated. The amounts of dopamine and 5-hydroxytryptamine agree well with the distribution of green and yellow fluorescence, respectively, in the ganglia.There are many similarities between the vertebrate and the molluscan monoaminergic neurons. The morphology of the neurons is the same, the intraneuronal distribution of the monoamines is identical, depletion experiments with reserpine and denervation experiments give the same results, and the synaptic arrangement of monoaminergic fibres on non-adrenergic neurons has the same appearance. Apparently, however, dopamine and 5-hydroxytryptamine are the only monoamines acting as neuronal transmitters in the species investigated.

Pheromone reception in the males of the amphipod Gammarus duebeni Lilljeborg

Experiments were carried out to test whether water transport of pheromone from female to male takes place in the amphipod Gammarus duebeni. In G. duebeni sexual dimorphism occurs im presumed chemosensory receptor mechanisms of the 2nd antenna, which carries calceoli in the male. Sexually mature females were fed 3H-acetyl-glucosamine-labelled trout liver and became highly radioactive. Males were exposed to water containing such females. They reacted by swimming to the double net partition separating them from the females. After I to 1 h exposure scintillator measurements on males showed about 1000 times higher radioactivity per mg body weight in the 2nd antenna than in the remainder of the body. Light microscope autoradiography showed selective labelling of calceoli sites. This was taken to indicate that a 3H-labelled sex pheromone from the female had reached receptors in the male calceoli.

Pheromone Transport and Reception in an Amphipod

Sexual dimorphism in the second antennae of the amphipod Gammarus duebeni Lilljeborg is connected with the reception in the male of a female sex pheromone transported through the water. Investigations on tritium-labeled specimens were carried out with scintillator and autoradiographic techniques.

Life cycle of the endoparasitic nematophagous fungus Meria coniospora: a light and electron microscopic study

The obligate endoparasitic fungus Meria coniospora lives its entire vegetative life within infected nematodes. Conidia of M. coniospora infect the nematode Panagrellus redivivus mainly in the mouth region. The infection, starting with adhesion of conidia to the nematode surface, growth of trophic hyphae, production of conidiophores and conidia, was followed using light, scanning and transmission electron microscopy.

On the monoamine-storing cells in the heart of Lampefra fluviatilis and L. planeri (Cyclostomata)

The heart of Lampetra fluviatilis and L. planeri were studied by means of a fluorescence method specific for the histochemical demonstration of certain catecholamines and tryptamines. Numerous flat and multipolar cells outlining the walls of the lumina were found to emit a green to yellow fluorescence. They were most abundant in the sinus venosus and the atrium. The fluorescence derives from noradrenaline and adrenaline, both of which are present in large quantities in the specific cells of the atrium and the sinus venosus, whereas the corresponding cells in the ventricle contain almost only adrenaline. Chemically, neither 5-hydroxytryptamine nor dopamine was found in the heart. The Lampetra heart receives no adrenergic nerves. Fluorescent cells and nerve fibres were found in the outermost layer of the bulbus arteriosus. Preliminary microspectrographic analyses revealed that some of these structures showed activation and emission spectra typical of catecholamines whereas others behaved in these respects like 5-hydroxytryptamine. A third type of fluorescent structure deviated from these patterns and is still unidentified.

The growth response of frog tadpoles to pituitary implants from different vertebrates.

Abstract Adenohypophysial tissue from different vertebrates was implanted in normal frog tadpoles, and the growth response of the latter was followed by weighing. The tadpoles appeared to be responsive to implants from members of the main classes of Tetrapoda (mammals, birds, reptiles, anurans) with the exception of Urodela ( Triturus ). The response, when present, was clear within 4 days after implantation.

Experimental and structural analysis of the function of saccus vasculosus in rainbow trout, Salmo gairdneri (Richardson)

SummaryInjection of a saccus vasculosus homogenate from sea water adapted rainbow trout into the third brain ventricle of fresh-water rainbow trout increased the survival time of the latter in sea water of high salinity. This indicated an active role of saccus vasculosus in osmoregulation.Autoradiographic analysis of brains from injected fish that had received a saccus vasculosus homogenate from sea water adapted specimens, in which the coronet cells of saccus vasculosus had previously been labelled with 3H-glucoseamine, revealed actual incorporation of labelled material into brain cells, especially in the hypothalamic region. The intracellular distribution of labelled material in the coronet cells of rainbow trout labelled with 3H-glucoseamine strongly indicates that such material represents a secretory product; it is therefore probable that the observed incorporation of label into brain cells of injected fish actually reflects normal processing of material secreted from the coronet cells.In the scanning electron microscope, the inside wall of the third brain ventricle of the rainbow trout was in many areas found to be covered with cilia. These apparently serve to keep liquor in circulation. The observation, both in injected and control animals, of free globules among these cilia supports the idea of an intra-ventricular transport of detached coronet cell material to the infundibular recess, as indicated by the autoradiographic analysis.

Ultrastructural changes in the coronet cells of the saccus vasculosus from rainbow trout, Salmo gairdneri (Richardson), kept in sea water

SummaryThe coronet cells of saccus vasculosus of fresh-water living and sea-water adapted rainbow trout were studied with the electron microscope, with special regard to changes in the latter group. Only quantitative differences were observed, namely a raised number of mitochondria in the apical region and the head and also a concentration of the agranular endoplasmic reticulum with a higher amount of electron-dense material and vesicles around the Golgi saccules. Together, these findings suggest a secretory function for the coronet cell. A supposed transport of vesicles from the head region of the coronet cell out into the globules is suggested. Interrelation between primary and secondary vesicles is discussed.

Metabolic activity in the saccus vasculosus of the rainbow trout, salmo gairdneri (richardson)

SummaryLabelling experiments to test mucopolysaccharide synthesis in the saccus vasculosus of the rainbow trout gave negative results and provoked analysis of succinic dehydrogenase activity in the coronet cells. Such activity was almost absent in the fresh-water living rainbow trout but was intense in sea water adapted individuals as well as in a sea water teleost, the flounder. Conversely, in sea water adapted rainbow trout which had been transferred back to fresh-water, activity had again decreased. In the sea water adapted rainbow trout high succinic dehydrogenase activity was paralleled by strongly positive staining with alcian blue, indicating the presence of mucopolysaccharides. The latter fishes also showed incorporation of N-acetyl-3H-glucosamine. Our findings indicate a role for saccus vasculosus in adaptation for osmoregulation in sea water and favour the hypothesis of a secretory function for the coronet cells.

Ultrastructural cerebrovascular changes in a model of subarachnoid hemorrhage in baboon based on triple cisternal blood injection

In a subarachnoid hemorrhage model in the baboon, achieved through three cisternal blood injections with 1-day intervals, the cerebral arteries were dissected out 7 days after the first blood injection for electron microscopy All the animals showed ultrastructural changes in the cerebral arteries: two with severe, one with moderate, and three with mild alterations in the vessel walls. The most constant findings were seen in the muscle cells of the media layer. Fragmentation of the nuclei was frequently observed together with cytoplasmic vacuoles. Scattered groups or single degenerated muscle cells were also noted. In the intima the changes included rounding of the nuclei along with the appearance of cytoplasmic vacuoles. Desquamation or flattening of the endothelium and loss of tight junctions were encountered in some vessel areas. Degenerating mitochondria were a common finding.