EMBRYOLOGY 



upon the rectum, and anteriorly, a little below the upper extremity of 

 the neck (os internum), where it is reflected upon the urinary bladder. 

 At the sides of the uterus, the peritoneal covering, a little below the 

 entrance of the Fallopian tubes, becomes loosely attached and leaves 

 a line for the penetration of the vessels and nerves. Fig. 199 (C), 

 giving a view of the interior of the uterus, shows a triangular cavity, 

 with two cornua corresponding to the openings of the Fallopian tubes, 

 and very thick walls, the greatest part of which is composed of layers 

 and bands of non-striated muscular fibres. 



The muscular walls of the uterus are composed of non-striated fibres 

 arranged in several layers. These fibres are spindle-shaped and always 



Fig. 199. Virgin uterus {from a woman twenty-two years old} . A. anterior view. B. median 

 longitudinal section. C. transverse longitudinal section (Sappey). 



A. I, body; 2, 2, angles; 3, cervix; 4, site of the os internum ; 5, vaginal portion of the cervix; 6, ex- 

 ternal os ; 7, 7, vagina. 



B. i, i, profile of the anterior surface; 2, vesico-uterine cul-de-sac; 3, 3, profile of the posterior sur- 

 face; 4, body; 5, neck; 6, isthmus; 7, cavity of the body; 8, cavity of the cervix; 9, os internum ; 

 10, anterior lip of the os externum; n, posterior lip; 12, 12, vagina. 



C. i, cavity of the body; 2, lateral wall; 3, superior wall; 4> 4, cornua; 5, os internum; 6, cavity 

 of the cervix ; 7, arbor vitae of the cervix ; 8, os externum ; 9, 9, vagina. 



nucleated, the nucleus presenting one or two large granules that have 

 been taken for nucleoli. They are closely bound together, so that they 

 are isolated with great difficulty. In addition to an amorphous adhesive 

 substance between the muscular fibres, there are many rounded and 

 spindle-shaped cells of connective tissue, and a few elastic fibres. The 

 muscular fibres of the uterus enlarge immensely during gestation, becom- 

 ing at that tim.e ten or fifteen times as long and five or six times as broad 

 as they are in the unimpregnated state. They are united into bundles, or 

 fasciculi, which in certain of the layers interlace with each other in every 

 direction. The fibres are divided into external, middle and internal layers. 



