Laminar Acetylcholinesterase localization in the optic tectum of five seawater teleosts.

The histochemical localization of acetylcholinesterase in the optic tectum of seawater teleosts shows a characteristic laminar distribution which parallels the histological structure of the nervous centre. Significant differences have been observed between Gobius and the other 4 species of teleosts examined. It seems likely that cholinergic mechanisms play an important role in the function of teleost optic tectum.     

The localization of acetylcholinesterase in the optic lobe in the developing chick embryo

Summary The localization of acetylcholinesterase (AChE) in the optic lobe in the developing chick embryo was studied histochemically and biochemically. The histochemical reaction of AChE increased remarkably between stage 42 and 44 especially in the neuropile. The increase of the biochemical activity of the AChE in the synaptic membrane fraction occurred at a later stage than that in the microsomal fraction. These findings can be interpreted as the result of axonal transport of the enzyme from the synthetic to the synaptic site.Acknowledgments. The authors wish to thank Prof. Yasuharu Kuwahara, Cataract Research Institute, for the use of his cryostat and other laboratory facilities, Dr. Koji Kami, Department of Anatomy, Keio University School of Medicine, for his valuable advice regarding histochemistry.     

Synaptic junctions in the developing chick optic tectum

Riassunto Giunzioni sinaptiche compaiono in differenti strati plessiformi del tetto ottico dell'embrione di pollo, a partire dal 12⁰ giorno di incubazione: aumentano di numero fra il 12^o ed il 18^o giorno e, in maniera critica, fra questo e le prime ore dopo la schiusa.

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This work was supported by a grant from the Consiglio Nazionale delle Ricerche (C.N.R.) Rome, Italy.     

Comparative survey on enzyme localization,ultrastructural arrangement and functional organization in the optic tectum of non-mammalian vertebrates

Summary The histochemical localization of some enzymatic activities is surveyed in the optic tectum of vertebrates from cyclostomes to birds. These data are compared with results arising from ultrastructural and experimental works in order to outline some possible connections between enzyme localization and functional organization of the optic tectum. The most interesting result derives from acetylcholinesterase which, in the majority of vertebrate species, is localized in tectal layers in which visual and other sensitive afferents discharge. Such a situation, together with some experimental and developmental results, suggests that cholinergic mechanisms play an important role in the function of the optic tectum and that these mechanisms are worthy of further and more detailed investigations.Acknowledgments. The author is grateful to Prof.S. Leghissa, Dr. F. Ciani andDr. L. Villani for the permission to use the photographs 8–11 of the present paper.     

Selectivity to spatial frequencies in the pigeon's optic tectum cells]

Extracellular cell recordings in the pigeon optic tectum show a selectivity of response to different sine-wave gratings presented in motion. The optimal frequencies are found to be between 0.4 and 0.9 cycle/degree and are independent of direction, orientation and velocity.     

Enzymatic patterns in reptilian brain. Histochemical characterization of the optic tectum

Summary The enzymatic patterns present in the optic tectum of 4 species belonging to different reptilian orders seem related to the degree of structural and functional organization reached by the nervous centre, as in other vertebrates. In particular the AChE localization in reptiles is representative of a evolutionary sequence in the distribution of this enzyme in the optic tectum along the tetrapode series.     

The reticulo-endothelial localization of hepatic acetylcholinesterase

Zusammenfassung Die Acetylcholinesterase wurde histochemisch in den sinusoidal-reticulo-endothelialen Zellen der Kaninchenleber gefunden. Es wird angenommen, dass das Enzym an der Fett- und Esterumwandlung beteiligt ist.     

Electron microscopic localization of acetylcholinesterase in small multiple endings in the extraocular muscles of the rat

Zusammenfassung Elektronenmikroskopisch wird gezeigt, dass die aus nichtmyelinhaltigen Nervenfasern stammenden kleinen motorischen Endplatten in den Augenmuskeln der Ratte Azetylcholinesterase-Aktivität haben.     

Nerve endings isolated from chick embryonic optic tectum. 2. Developmental aspects of synaptosomal membrane

Summary Fractions enriched in nerve endings (synaptosomes) have been isolated from chick embryonic optic tectum during development. After osmotic shock, these fractions appeared to be enriched in membranes which during development acquire typical features of mature synaptosomal membranes.     

Nerve endings isolated from chick embryonic optic tectum. 1. Developmental aspects of intact synaptosomes

Summary Fractions enriched in nerve endings (synaptosomes) have been isolated from optic tectum of chick embryos at 16 and 18 days of incubation and of chicks immediately after hatching. Morphological aspects of nerve endings have been examined with special regard to the appearance of synaptic thickenings and synaptic vesicles.     

Concerning the anchoring of acetylcholinesterase in biomembranes

Summary Highly purified acetylcholinesterases from various sources do not contain hydroxyproline and hydroxylysine, indicating the absence of a collagenlike tail. The enzymes examined are therefore bound to the membrane in a different way compared with acetylcholinesterase isolated from electric organ.     

Concerning the anchoring of acetylcholinesterase in biomembranes

Highly purified acetylcholinesterases from various sources do not contain hydroxyproline and hydroxylysine, indicating the absence of a collagenlike 'tail'. The enzymes examined are therefore bound to the membrane in a different way compared with acetylcholinesterase isolated from electric organ.     

Histochemical and cytochemical observations on the acetylcholinesterase (AChE) localization in the superior cervical ganglion (SCG) after preganglionic sympathectomy of the neonatal rat

Summary Results of histochemical and cytochemical reactions show that after the section of preganglionic nerve trunk performed in newborn animals, the appearance and the individual increase in AChE activity in non-innervated nerve cells follow the pattern of normally innervated ganglion cell.     

Evolution of a retinal specific lactate dehydrogenase isozyme in teleosts

Résumé Un troisième locus génétique indique la présence d'un unique isozyme de déshydrogénase lactique ne fonctionnant que dans les tissus neuraux des Téléostéens, surtout dans la rétine neurale. La fonction de gène ne se manifeste pas dans les ordres de poissons primitifs. Ces résultats suggèrent une différence de métabolisme rétinien entre les Téléostéens et les classes de poissons plus primitifs.     

Histochemical and cytochemical observations on the acetylcholinesterase (AChE) localization in the superior cervical ganglion (SCG) after preganglionic sympathectomy of the neonatal rat.

Results of histochemical and cytochemical reactions show that after the section of preganglionic nerve trunk performed in newborn animals, the appearance and the individual increase in AChE activity in non-innervated nerve cells follow the pattern of normally innervated ganglion cell.     

Histochemical localization of acetylcholinesterase in the glycogen body (sinus rhomboidalis) of common brown dove,Streptopelia senegalensis and house sparrow,Passer domesticus

Summary Acetylcholinesterase (AChE) activity was studied in the glycogen bodies of the spinal cords of 2 birds namelyStreptopelia senegalensis andPasser domesticus. A possible functional significance of AChE in the light of relative enzymatic localization especially in Hoffmann-Kolliker nuclei (motor cell groups), substantia gelatinosa and other regions of gray matter of 2 avian glycogen bodies has been discussed.     

Morphological evidence for a direct neuroendocrine GABAergic control of the anterior pituitary in teleosts

The anterior pituitary of teleosts is unique among vertebrates in receiving a direct innervation which represents the morphological support of the neuroendocrine control of pars distalis functions. The participation of GABAergic fibers in this innervation was studied by means of immunocytochemistry at the light and electron microscopic levels, using antibodies against GABA. Immunoreactive fibers, characterized by the presence of small clear and dense cored vesicles, were detected in all parts of the gland. Immunopositive terminals were found in close, sometimes synaptic-like, contact with most glandular cell types in the anterior lobe. The data strongly suggest that in teleosts, as in mammals, GABA is involved in the neuroendocrine control of anterior pituitary functions.     

Morphological evidence for a direct neuroendocrine GABAergic control of the anterior pituitary in teleosts

Summary The anterior pituitary of teleosts is unique among vertebrates in receiving a direct innervation which represents the morphological support of the neuroendocrine control of pars distalis functions. The participation of GABAergic fibers in this innervation was studied by means of immunocytochemistry at the light and electron microscopic levels, using antibodies against GABA. Immunoreactive fibers, characterized by the presence of small clear and dense cored vesicles, were detected in all parts of the gland. Immunopositive terminals were found in close, sometimes synaptic-like, contact with most glandular cell types in the anterior lobe. The data strongly suggest that in teleosts, as in mammals, GABA is involved in the neuroendocrine control of anterior pituitary functions.