EMBRYOLOGY 



the membrane being applied directly to the uterine walls. It is cov- 

 ered by a single layer of cylindrical epithelial cells, with delicate cilia, 

 the movements of which are from without inward, toward the openings 

 of the Fallopian tubes. Examination of the surface of the membrane 

 with a low magnifying power shows the openings of a great number of 

 tubular glands. These glands usually are simple, sometimes branched, 

 dividing, about midway between the opening and the lower extremity, 

 into two and very rarely into three secondary tubules. Their course 

 usually is tortuous, so that their length frequently exceeds the thick- 

 ness of the mucous membrane. The openings of these tubes are about 



3^0- of an inch (72 /x) in 

 diameter. Their secre- 

 tion, which forms a thin 

 layer of mucus on the 

 surface of the membrane 

 in health, is grayish, vis- 

 cid and feebly alkaline. 

 The tubes themselves 

 have very thin structure- 

 less walls and are lined 

 with cylindrical ciliated 

 epithelial cells. 



The changes which 

 the mucous membrane of 

 the body of the uterus 

 undergoes during men- 

 struation are remarkable. 



Fig. 201. - Superficial muscular fibres of the anterior surface of Under Ordinary COndi- 



tions its thickness is ^V 

 to -j 1 ^ of an inch (i to 

 1.8 millimeters); but it 

 measures during the menstrual period \ to \ of an inch (4.2 to 6.4 milli- 

 meters). 



In the cervix the membrane is paler, firmer and thicker than the 

 membrane of the body of the uterus, and between these two mucous 

 surfaces there is a distinct line of demarcation. It is more loosely 

 attached to the subjacent tissue in the cervix, and the anterior and pos- 

 terior surfaces of the neck present an appearance of folds radiating 

 from the median line, forming what has been called the arbor vitae 

 uteri, or plicae palmatae. Throughout the cervical membrane, are 

 mucous glands, and in addition, in the lower portion, are a few rounded, 

 semitransparent, closed follicles, called the ovules of Naboth, which are 



a, a, round ligaments ; b, b, Fallopian tubes ; c, c, c, e, e, trans- 

 verse fibres; d,f, longitudinal fibres. 



