THE UTERUS. 



257 



in others lower and more cuboidal. In addition to the usual tubular crypts, 

 which although larger resemble those in the body, the cervical glands include 

 wide diverticulated mucous follicles producing a clear peculiarly tenacious 

 secretion. When the latter is retained, the glands are converted into cysts that 

 appear as minute vesicles between the characteristically converging folds of the 

 cervical mucosa and were formerly known as the ovula Nabothi. The abrupt 

 transition of the columnar epithelium of the cervical canal into the stratified 

 squamous cells covering the vaginal portion of the uterus takes place, before 

 pregnancy has occurred, at the inner border of the external orifice. After 

 the changes incident to pregnancy have affected the uterus, this transition lies 



Fold of mucosa - 



:. '.*&.* 



cess between -XvitK 

 s, containing* '"..V.. . j 



Recess between 

 folds 



secretion 



Cervical glands 



Muscle 



Blood-vessel 



FIG. 306. Longitudinal section of cervical mucous membrane, showing glands opening into recesses 



between the plicae. X 50. 



higher, approximately the lower half of the cervical canal then being clothed 

 with the squamous epithelium. The change of the cervical mucosa into that 

 lining the body of the uterus is gradual and without definite demarcation. 



The muscular coat, or myometrium, is composed of bundles of 

 involuntary muscle arranged with little regularity; it is possible, however, 

 to distinguish two general strata a robust inner layer, in which the bundles 

 possess a circular disposition, and a thin imperfect outer layer, whose 

 component bundles are for the most part longitudinal. The innermost 

 bundles of the circular layer are oblique and longitudinal and sometimes 

 described as a distinct submucous layer. The thick circular layer, the chief 

 component of the myometrium, is distinguished by the number and size of 

 the venous channels that traverse the intermuscular connective tissue; hence 

 its designation as the stratum vasculare. At the orifices of the oviducts and 

 the internal cervical opening, the disposition of the muscle-bundles suggests 

 a sphincter. The longitudinal muscle is most distinct over the fundus and 

 body, being unrepresented in the cervical segment. Here the circular and 

 oblique bundles are intermingled with a considerable quantity of fibre-elastic 

 tissue, an arrangement conferring greater resistance and hardness upon the 



17 



