Hair morphology

In acute animal studies, the concentrations that killed at least 70% of animals with an 8-hour exposure were 170 ppm for mice, 700 ppm for cats, 2000 ppm for rabbits, and 4000-6000 ppm for rats. Symptoms included inflammation of the mucous membranes of the eyes and nose, followed by central nervous system depression and death ftom respiratory failure. Repeated exposure of rats 6 hours/day, 5 days/week for 4 weeks caused skin and eye irritation and growth depression at 40 ppm at 160 and 62 5 ppm, it resulted in loss of hair, morphologic liver damage, and increased mortality. "... 

Insect antennae vary tremendously in size and shape, but two common forms are filiform (a single cylinder) and pectinate (feathery arrays of many cylinders). Most of the published morphological information on insect antennae concentrates on sensory hairs (e.g. Zacharuk, 1985 Steinbrecht, 1987, 1999 Zacharuk and Shields, 1991). Descriptions of sensory hair morphology are necessary for biomechanical analyses and interpretation, but it is equally important to have... 

Taupin, J. M. (2004). Forensic hair morphology comparison—A dying art or junk science Sci. Justice 44, 95-100. 

The component of hair morphology located in the center of some thicker fibers and consisting of a loosely packed porous cellular structure is called the medulla. The medulla of human hair fibers apparently does not contribute to their mechanical properties, although occasionally fractures can initiate in the vicinity of medullary structures, which provide flaws for the initiation of cracks. Recent work at TRl/Princeton has also shown that the medulla does contribute to the optical properties of human hair fibers. 

O Connor SD, Komisarek KL, Baldeschwieler JD (1995) Atomic force microscopy of human hair cuticles a microscopic study of environmental effects on hair morphology. J Investig Dermatol 105(l) 96-99... 

Specific areas discussed include advantages and uses of the stamen-hair system, review of floral and stamen-hair morphology, cultivation of stock plants, screening of untreated plants for abnormally high aberration rates, preparation and handling of cuttings for experimental use, and consideration of flower production and of statistically acceptable numbers of cuttings and stamens rec[uired for a typical experiment. 

The polymer and glass microspheres employed in the pressure-sensitive release of chemicals range in size from 1 pm to 1 mm in diameter. (For comparison, a human hair is typically 80-100 pm in diameter.A scanning electron micrograph illustrating the morphology of the particles appears in color Fig. 14.2.1. ... 

Mechanical transduction depends on activation of ion channels linked to extracellular and intracellular structures. A comprehensive model for hair-cell transduction has emerged, derived primarily from biophysical and morphological investigations. Residing in the mechanore-ceptive organelle of a hair cell, the hair bundle, the transduction apparatus consists of at least three components the transduction channel, a mechanically gated ion channel the tip link, an extracellular filament that transmits force to the channel s gate and the adaptation motor,... 

Morphological damage by aminoglycosides is not limited to hair cells, and the cochlear sensory epithelium may become completely replaced by a squamous epithelium after prolonged drug treatment. Changes also occur in the... 

Heimich, G. et al.. Glandular hairs of Sigesbeckia jorullensis Kunth (Asteraceae) morphology, histochemistry and composition of essential oil, Ann. Bot., 89, 459, 2002. 

The principal pigment of human skin, hair, and eyes is melanin, which is synthesized in specialized cells, the melanocytes. They lie between the epidermis (outer layer) and the dermis (inner layer) as shown in Box 8-F. Melanocytes originate from embryonic nervous tissue and migrate into the skin by the third month of fetal life. They retain the highly branched morphology of neurons. Persons of different races all have the same numbers of melanocytes but the numbers and sizes of the pigmented melanosomes (Box 8-F) vary as does the content and chemical composition of the melanin.a d Melanosomes not only are found in the dendrites of the melanocytes but are transferred from them into adjacent epithelial cells.6 1... 

Other evidence on morphological modifications attributed to HS treatment concern root hair development. In this sense, Concheri et al. (1994) identified a strong proliferation of root hairs compared to control plants in wheat root supplemented with HS up to a concentration of lOmgC liter-1, with best results for HMS and LMS obtained with 5 and O.lmgCliter-1, respectively. 

In the last 40 years of research on HS biological activity, several aspects have been elucidated. The favorable morphological effects of HS on plants regarding growth enhancement have been demonstrated on several plant species under different study conditions. Besides these observations, effects on morphogenesis have also been demonstrated in terms of (a) the induction of lateral root formation and (b) root hair initiation and development in intact plants and stimulation of root and shoot development in treated cell calluses. 

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