CH. LVIIL] THE UTERUS 825 



fatty and albuminous granules (yolk spherules), except in the part 

 around the nucleus, which is comparatively free from these granules. 

 It contains a nucleus which has the usual structure of nuclei ; there is 

 generally one very well-marked nucleolus. The nucleus and nucleolus 

 are still often called by their old names, germinal vesicle and germinal 

 spot respectively. An attraction sphere, not shown in the figure, is 

 also present, and a fine membrane, the vitelline membrane, is said to 

 lie between the protoplasm and the zona pellucida. 



The oocytes are developed from the primitive germ cells which 

 in the earliest stages are interspersed between the cells of the germinal 

 epithelium. The primitive germ cells divide and produce oogonia ; 

 and by the division of the oogonia, oocytes are formed (fig. 618). As 

 the oogonia and oocytes are developed they sink into the stroma, 

 surrounded by cells, produced by the proliferation of the germinal 

 epithelium, which are destined to form the membrana granulosa and 

 the discus proligerus. 



FIG. 619. Section of the lining membrane of a human uterus at the period of commencing pregnancy, 

 showing the arrangement of the glands, d, d, d, with their orifices, a, a, a, on the internal surface 

 of the organ. Twice the natural size. 



The Fallopian tubes have externally a serous coat derived from 

 the peritoneum, then a muscular coat (longitudinal fibres outside, 

 circular inside), and most internally a very vascular mucous mem- 

 brane thrown into longitudinal folds, and covered with ciliated epi- 

 thelium. 



The uterus consists of the same three layers. The muscular 

 coat is, however, very thick and is made up of two strata imperfectly 

 separated by connective tissue and blood-vessels. Of these the 

 thinner outer division is the true muscular coat, the fibres of which 

 are arranged partly longitudinally, partly circularly. The inner 

 division is very thick ; its fibres run chiefly in a circular direction ; 

 the extremities of the uterine glands extend into its internal surface. 

 It is in fact a much hypertrophied muscularis mucosse. 



The mucous membrane is thick, and consists of a corium of soft 

 connective tissue, lined with ciliated epithelium ; this is continued 

 down into long tubular glands which have, as a rule, a convoluted 

 course. In the cervix the glands are shorter. Near the os uteri the 



