Investigations of the nerves of the rabbit lung, by light and electron microscopy, showed a dense acetylcholinesterase-positive innervation of the bronchi through the bronchiolar level. Large nerve bundles were found to decrease in size as they progressed from extrachondral to subchondral connective tissue, forming complex networks of mostly terminal fibres in the muscle layer. In several instances single fibres penetrated the submucosal layer and approached the mucosa. Gangliocytes, which also reacted positively for cholinesterase, were visible in the vicinity of the large peribronchial bundles. Gangliocytes rarely were seen in association with the vasculature. Blood vessels received a much less dense cholinesterase-positive nerve supply than the bronchi. Single, non-terminal fibres were noted at the adventitiomedial junction of the pulmonary artery and vein. In addition, segments of nerve fibres (networks) were observed in the arterial and venous smooth muscle layers. Cholinesterase-positive innervation was even less extensive in the veins than in the arteries. Methods LIGHT MICROSCOPYAlbino rabbits, weighing an average of 3 kg, were injected intraperitoneally with sodium pentobarbitol. The lungs, judged to be free of disease on macroscopic examination, were placed on aluminium foil and frozen on dry ice (-70°C).Serial frozen sections of 20-30 ,m were collected on coverslips, air-dried for a few minutes, and fixed in 4% neutral formol-saline solution for 15 minutes. The sections were incubated at 37°C for 90 minutes, according to the procedure of Karnovsky and Roots'6 as modified by El-Badawi and Schenk."7The substrate for the specific cholinesterase reaction was acetylthiocholine iodide; tetraisopropylpyrophosphoramide (iso-OMPA) at a concentration of 80 mmolI was used to inhibit non-specific cholinesterase. ELECTRON MICROSCOPYA modification of the procedure described by Kokko et al'8 was used to demonstrate acetylcholinesterase for electron microscopy. After a saline washout of the pulmonary circulation the left lung was perfused with a solution of 3% formaldehyde and 1% glutaraldehyde in Sorensen's phosphate buffer (pH 7.0) through the pulmonary artery 703 on 27 April 2019 by guest. Protected by copyright.

No abstract

This experiment investigated the differential sensitivity of various areas of the retina using flicker. For 12 subjects testing was carried out in the fovea, and 5 degrees and 6 degrees temporal to the fovea using a wavelength of 555 nm. Testing was done both in the presence of a surround beam and in its absence. In all cases, there was a 2.5- to 4-fold increase in the amount of energy needed to perceive flicker as testing was shifted from the fovea to the periphery. A number of possible explanations are suggested to account for these findings.

Filamentous intranuclear rodlets were found in a majority of cells in a bronchiolar neuroepithelial body of a rabbit. These rodlets appear to be similar to structures that have been described primarily in neural tissues. They are composed of large bundles of microfibrils made up of smaller subbundles. No close association with any nuclear structure is seen. Although no function can as yet be ascribed to intranuclear rodlets, their demonstration in a neuroepithelial body may be of importance of the understanding of the function of both structures.