Volume 1

A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling.

Landois, L. (Leonard), 1837-1902. Lehrbuch der Physiologie des Menschen. English

Date:: 1891

Credit: A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the seventh German edition with additions by William Stirling. Source: Wellcome Collection.

588/602 page 548

$being cylindrical. Towards the base of the hair-follicle it becomes narrower, and is united to, and continuous with, the cells of the root of the hair itself, at least in fully developed hairs. The horny layer of the epidermis continues to retain its properties as far down as the orifice of the sebaceous follicle ; below this point, however, it is continued as the inner root-sheath. This consists of (1) a single layer of elongated, fiat, homogeneous, non-nucleated cells (figs. 358, 6, 361, /— Henle's layer) placed next and within the outer root-sheath. Within this lies (2) Huxleijs layer (figs. 358, 5, 361, g), consisting of nucleated elongated polygonal cells (fig. 358, x, and 3), while the cufide of the hair-follicle is composed of cells analogous to those of the surface of the hair itself. Towards the bulb of the hair these three layers become fused together. [Coverings of a hair-follicle arranged from without inwards— ( {a) Longitudinally arranged fibrous tissue. 1. Fibrous layers, ^ Circularly arranged spindle cells. 2. Glass-like (hyaline) membrane. ( {a) Outer root-sheath. (h) Inner root-sheath. ( (c) Cuticle of the hair. ( Henle's layer. ( Huxley's layer. 3. Epithelial layers. 4. The hair itself. The arrector pill muscle (fig. 358, A) is a fan-like arrangement of a layer of smooth muscular fibres, attached below to the side of a hair-follicle and extending towards the surface of the chorium ; as it stretches obliquely upwards, it subtends the obtuse angle formed by the hair-follicle and the surface of the skin, [or, in other words, it forms an acute angle with the hair-follicle, and between it and the follicle lies the sebaceous gland]. When these muscles contract, they raise and erect the hair-follicles, pro- ducing the condition of cutis anserina or gooseskin. As the sebaceous gland lies in the angle between the muscle and the hair-follicle, contraction of the muscle compresses the gland and favours the eva- cuation of the sebaceous secretion. It also com- presses the blood-vessels of the papilla {Unna). The hair with its large bulbous extremity—hair- bulb—sits upon, or rather embraces, the papilla. It consists of (1) the marrow or medulla (fig. 358, i), which is absent in woolly hair and in the hairs formed during the first year of life. It is composed of two or three rows of cubical cells (H, c). (2) Outside this lies the thicker cortex (A), which con- sists of elongated, rigid, horny, fibrous cells (H,/;/), Fig. 36L Transverse section of a Lair • between these cells He the pigment follicle. a, outer librous coat, i • /o\ rm £ ü xi, i • • with h, blood-vessels; c, inner granules of the hair. (3) The surface of the hair is circularly disposed layer ; d, covered with a cuticle (/i;), which consists of imbri- glass-like layer ; e, outer, /, g, ^ated layers of non-nucleated squames. inner, root-sheath;/outer layer ci, a- * ^- a • ^\ ^ of the same (Henle's sheath) ; g, [Nerves.-Numerous nerve-fibres are distributed m the inner layer of the same (Hux-hair-follicles (§ 424).] ^ ^ . ^ . ^ , ley's sheath) ; h, cuticle ; I, hair. Grey Hair.—When the hair becomes grey, as u? old age this is due to defective formation of pigment m the cortical part. The silvery appearance of white hair is increased when small air-cavities are developed, es[»ecially in the medulla, and to a less extent in the cortex, where they reflect the light. Landois records a case of the hair becoming suddenly grey, in a man whose hair became grey during a single night, in the course of an attack of delirium tremens. Numerous air-spaces$