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STUDENTS HISTOLOGY 



SEBACEOUS GLANDS 



These glands are little sacs or lobules, one or more of which 

 open into each hair -follicle. These sacs are entirely filled with 

 polyhedral epithelial cells (vide Fig. 71) . At the neck of the gland 



FIG. 71. SINGLE LOBULE OF A SEBACEOUS GLAND (X 400). 



A. The fibrous wall of the sac. 



B. Membrane propria. 



C. Polyhedral cells filling the sac completely. 



D. Fatty degeneration of the parenchyma at the neck of the gland, formation of sebum. 



the cells become granular, fatty, and disintegrated, producing the 

 sebum. 



THE NAILS 



The peculiar tissue of the nails corresponds to the stratum 

 lucidum of the epidermis developed to an extreme degree. The 

 nail rests upon a nail -bed, which represents the corium and the 

 Malpighian layer of the epidermis. Minute longitudinal ridges 

 take the place of papillae. The root of the nails is imbedded in a 

 part of the nail -bed called the matrix, from which its growth 

 occurs. 



PRACTICAL DEMONSTRATION 



Remove the skin from the parts below as soon after death as practicable. 

 Tissue may frequently be secured after surgical operations from stumps, etc. 

 Dissect deeply, so as to preserve the subcutaneous tissue. Small cubes from 

 the finger-tips, the palm of the hand, the scalp, and the groin may be hardened 

 quickly in strong alcohol; and vertical sections should be made as soon as the 



