THE EXTERNAL ORGANS. 



261 



seoaceous glands are numerous. In addition to the investment of skin, 

 each labium majus contains a layer of subcutaneous fat, between which 

 and the integument lies a thin stratum of involuntary muscle, tunica 

 dartolabialis, continued forwards from the dartos of the perineum. The 

 centre of the labium is occupied by a fairly well defined mass of fat, the 

 corpuc adiposum, that is separated from the subcutaneous tissue by a 

 delicate fibre-elastic membrane. 



The labia minora or nymphae are thin folds of delicate skin, con- 

 tinuous with the greater labia at the bottom of the interlabial groove, on the 

 one hand, and with the mucous membrane lining the vestibule, on the other. 

 Although both surfaces are covered with integument, the protection and 



Central fat-body 

 \ 



Labium majus 



Labium minus 



Inner surface 



Sebaceous glands on external' 

 cutaneous surfaces 



Interlabial groove 



FIG. 309. Section across the labia of young child. X 18. 



contact with the vaginal secretions to which the median aspect of the fold is 

 subjected, modify the skin on the inner side so that it assumes the color and 

 appearance of a mucous membrane. The line of transition into the ves- 

 tibular mucosa follows the medial attachment of the fold. The absence of 

 mucous glands and the presence of sebaceous follicles on both surfaces are 

 differential characteristics of skin as contrasted with the adjacent mucous 

 membrane. In addition to the two cutaneous layers, the nymphse are 

 composed of an intermediate stratum of loose connective tissue, rich ia 

 blood-vessels and bundles of unstriped muscle, that resembles erectile tissue. 

 Hairs and fat are entirely wanting on the labia minora, but sebaceous and 

 sweat-glands are plentiful after the first few years. 



The vestibule, the space enclosed by the nymphae, is lined with 

 mucous membrane covered by stratified squamous epithelium and containing 

 many mucous glands. Close to the posterior margin of the urethral orifice, 

 or on the papilla that usually marks this opening, lie the small apertures of the 

 paraurethral ducts. These canals, also known as the tubes of Skene and from 

 1-2 cm. long, lead into smaller groups of branched tubules, which are regarded 

 as the homologues of the prostatic tubules. The ducts are lined with stratified 



