GENERATIVE ORGANS OF THE FEMALE. 



213 



after the ovum has become extruded. They consist of columns of 

 large yellowish cells, with intervening vascular fibrous tissue, which 

 converge to a central strand of connective tissue occupying the axis of 

 the nodule. The columns of cells are not unlike those of the cortex of 

 the suprarenal capsule. The corpus luteum is derived from the wall 

 of the follicle, which becomes thickened and folded by multiplication 

 and hypertrophy of its cells ; between the folds connective tissue and 

 blood-vessels grow in towards the centre, and in this way the columnar 

 arrangement above mentioned is produced. After persisting for a time 

 the corpus luteum gradually disappears, its tissue becoming merged 

 in the surrounding stroma. Corpora lutea grow much larger and 

 remain much longer persistent in the event of pregnancy supervening. 



FIG. 247. SECTION ACROSS THE FALLOPIAN TUBE. 



The Fallopian tubes are lined by a very vascular mucous membrane, 

 which is covered with ciliated epithelium, and has numerous longi- 

 tudinal folds. Externally they are covered by a serous coat, within 

 which is a thin longitudinal layer of plain muscular fibres overlying 

 circular fibres of the same tissue. 



The uterus is usually described as composed of two parts, the body 

 and cervix. The wall of the uterus is formed of the following layers : 



1. A serous layer, derived from the peritoneum, which covers the 

 greater part of the fundus. 



2. A muscular layer, which is of considerable thickness and is formed 

 of plain muscular fibres disposed in two imperfectly separated strata. 

 Of these the outer is the true muscular coat, and its fibres are 

 arranged partly longitudinally, partly circularly. The inner muscular 



