Application of Fluorescence Microscopy and Photomicrography to Woody Tissues

A procedure is described for making preparations of woody tissues for visual observation or photography by incident-light fluorescence microscopy. The chief advantages of the technic are the following:

(1) Reliable recognition of anatomical characteristics in wood without ordinary time-consuming histological technics.

(2) Examination of relatively larger surface areas of wood blocks than by usual methods.

(3) Visual observation and, if desired, photography of tissues and cell structure in dry or in nearly natural or fresh condition.

(4) Marked color contrast without the use of stains in many tissues, including specific types of cells comprising them.

(5) Improved color contrast by use of Congo red with aspects not usually obtained by other methods.     

Application of Fine Grain Processing and Condenser Illumination Enlarging to Photomicrography

Photomicrographs involving great resolution are usually made by means of long initial projection. This involves the use of heavy, often cumbersome, apparatus designed to eliminate vibration. This paper evaluates the possibility of using an intermediate projection distance equal to or greater than 160 mm., which is considered the minimum efficient distance, and recording the initial negative image in very fine grain. Then by critical enlarging a positive image is obtained which closely approaches the resolution obtainable by the finest long projection equipment. The initial short projection permits elimination of vibration difficulties attending long exposures so that critical printing at magnifications above 2000 × will give consistently good results, provided fine grain technic is mastered by the operator.     

Interval Scanning Photomicrography of Microbial Cell Populations

A procedure is presented for photographically recording growth and other changes occurring within microbial populations over a period of time.     

Quinacrine Fluorescence for Identifying Metaphase Chromosomes, with Special Reference to Photomicrography

Metaphase chromosomes of humans and other species can be identified by their quinacrine fluorescence patterns. For the study of human chromosomes, standard phytohemagglutinin-stimulated leukocytes are used. A 45-60 min interval of colchicine treatment is used to obtain a higher proportion of extended chromosomes with contiguous chromatids which have generally proved to be most informative. Slides are stained with 0.5% quinacrine for 6 min, rinsed in running tap water for 3 min, and rinsed and mounted in a Tris-maleate buffer at pH 5.6. For photomicrography, a microscope with an HBO 200 w high-pressure mercury vapor lamp, 3 mm BG 12 excitor filter, darkfield condenser, fluorite 95x objective, K510 barrier filter and a nonautomatic exposure microphotographic attachment with an 8x eyepiece is used. With this system, images of adequate brightness reach the film plane, thus making possible the use of fine-grain, high definition 35 mm films, such as Kodak Panatomic-X and H & W Control VTE panchromatic. Photographic prints of moderately high contrast are used for preparing karyotypes in which every human chromosome can usually be readily identified.     

Preparation of Chromosomes of Tetrahymena Pyriformis for Photomicrography

Conjugating animals of the protozoan, Tetrahymena pryiformis, were affixed to cover slips by means of Nissenbaum's fluid, followed immediately by 1:3 acetic-alcohol for 18-24 hr. After fixation, the material was transferred through a descending alcohol series to water, then hydrolyzed in 1 N HCl, washed in water, followed by immersion in 45% acetic acid and subsequent mounting in aceto-carmine. Photomicrographs were made using a phase-contrast microscope and Microfile film. The schedule resulted in preparations with abundant material, adequate spacing of chromosomes in a single plane, and excellent differentiation of the chromosomes from the cytoplasm.     

Preparation of Chromosomes of Tetrahymena Pyriformis for Photomicrography

Conjugating animals of the protozoan, Tetrahymena pryiformis, were affixed to cover slips by means of Nissenbaum's fluid, followed immediately by 1:3 acetic-alcohol for 18–24 hr. After fixation, the material was transferred through a descending alcohol series to water, then hydrolyzed in 1 N HCl, washed in water, followed by immersion in 45% acetic acid and subsequent mounting in aceto-carmine. Photomicrographs were made using a phase-contrast microscope and Microfile film. The schedule resulted in preparations with abundant material, adequate spacing of chromosomes in a single plane, and excellent differentiation of the chromosomes from the cytoplasm.