MEIBOMIAN GLANDS. 



323 





the sudoriparous glands. They belong to the variety of glands called tubu- 

 lar, and they consist of a nearly straight tube which penetrates the skin, and 

 a rounded or ovoid coil situated in the subcutaneous structure. These glands 

 are found only in the cartilaginous portion of the external auditory meatus, 

 where they exist in great numbers. 



The ducts of the ceruminous glands are short and nearly straight, sim- 

 ply penetrating the different layers of the skin, and are T ^- to -^ of an 

 inch (36 to 50 //,) in diameter. Their openings are rounded and about 

 gfa of an inch (93 /*) in diameter. They sometimes terminate in the upper 

 part of one of the hair-follicles. They present an external coat of fibrous 

 tissue and are lined with several layers of small, pale, nucleated epithelial 

 cells. 



The glandular coil is an ovoid or rounded, brownish mass, T fa to -^ or T *g 

 of an inch (O21 to O51 or 1'6 mm.) in diameter. It is simply a convoluted 

 tube, continuous with the excretory duct and terminating in a somewhat 

 dilated, rounded extremity. It occasionally presents small, lateral protru- 

 sions. The diameter of the tube is yj-g- to ^g- of an inch (83 to 100 /M). It 

 has a fibrous coat, with a longitudinal 

 layer of non-striated muscular fibres, and 

 externally a few elastic fibres. It is 

 lined by a single layer of irregularly 

 polygonal cells, which are -g-jjVrr to TsW 

 of an inch (12 to 20 p.) in diameter. 

 These cells contain a number of brown- 

 ish or yellowish pigmentary granules. 

 The tube forming the gland contains a 

 clear fluid mixed with a granular sub- 

 stance containing cells. 



In addition to the ceruminous glands, 

 sebaceous follicles are found connected 

 with the hair-follicles. The arrange- 

 ment of the ordinary sebaceous glands 

 and the ceruminous glands, which are 

 situated in different planes in the subcu- 

 taneous structure, is shown in Fig. 100. 



The Meibomian glands have essen- 

 tially the same structure as the ordinary 

 sebaceous glands. Their ducts, however, 

 are longer, and the terminal follicles 

 are arranged in a peculiar manner by 

 the sides of the tubes along their entire 

 length. These glands are situated part- 

 ly in the substance of the tarsal carti- 

 lages, between their posterior surfaces 

 and the conjunctiva! mucous membrane. They are placed at right angles to 

 the free border of the eyelids, opening upon the inner edge and occupying 



FIG. 101. Meibomian glands of the upper lid ; 

 magnified 7 diameters (Sappey). 



1, 1, free border of the lid ; 2, 2, anterior lip 

 penetrated by the eyelashes ; 3, 3, posteri- 

 or lip, with the openings of the Meibomian 

 glands ; 4, a gland passing obliquely at the 

 summit ; 5, another gland bent upon itself ; 

 6, 6, two glands in the form of racemose 

 glands at their origin ; 7, a very small gland ; 

 8, a medium-sized gland. 



