CHANGES IN NON-PREGNANT UTERUS 



71 



out into the cavity of the iiterus and are covered by an epithelial 

 layer, these being continuous with the epithelium of the surface.^ 

 The sub-epithelial mucosa, which is sometimes called the uterine 

 stroma, contains also a number of blood-vessels and lymph spaces. 

 The vessels are branches of the ovarian and uterine arteries and 

 veins. The uterus is also supplied by nerves which are referred to 

 in a future chapter (p. 561). 



In many of the lower Mammals the uterus is represented by two 

 tubes, called the horns of the uterus or uterine cornua, which may 

 unite posteriorly to form the corpus, or may, on the other hand, open 

 separately into the vagina. The arrangement of the different layers 

 in each of the cornua is essentially similar to that presented by the 

 corpus uteri in the human species. 





Fig. 5. — Cross-section through cervical canal of human uterus. 

 (From Williams' Ohstetrics. Appleton & Co.) 



The neck or cervix uteri, which is narrower- than the rest of the 

 organ, opens into the vagina by a transverse aperture known as the 

 OS. The vagina is the broad passage from the uterus to the exterior. 

 Its walls contaiii both longitudinally and circularly arranged muscle 

 fibres. Internally it is lined by a stratified scaly epithelium, 

 surrounded by erectile tissue. The entrance to the vagina from the 

 exterior is guarded by a thin fold of mucous membrane, which 

 usually becomes perforated at the first coition. This structure, which 

 is called the hymen, is peculiar to the human race.^ 



1 With regard to the function of the glands it is' clear that in their condition 

 of greatest development (if not at other times) this is secretory in character. 

 Witness the secretion of " uterine milk " during pregnancy (p. 4.32), and their 

 comparable condition in pseudo-pregnancy. Arthur Thomson, however, has 

 expressed the opinion that they are absorbent, and as evidence of this refers 

 to the supposed effects of the male ejaculate (seminal fluid) upon the female 

 (fi.g. in promoting enlargement of thyroid). See lecture in Brit. Med. Jour., 

 7th January 1922, "On Problems involved in the Congress of the Sexes in Man." 



^ The significance or function of the hymen is not certainly known. 

 Metchnikoff {The Mature of Man, English Edition, London, 1903) suggests 



3A 



