THE FEMALE REPRODUCTIVE ORGANS 519 



then become fertilized within the ovary; or an egg fertilized in the ab- 

 dominal cavity may perhaps subsequently become implanted in an empty 

 follicle. Development proceeding under such conditions results in an 

 ovarian pregnancy, at least seven well authenticated cases being now on 

 record (Bryce, Kerr and Teacher, "An Early Ovarian Pregnancy/' 

 1908). Ovarian pregnancies cannot proceed normally, and may early 

 call for surgical intervention. Occasionally a follicle may contain more 

 than one ovum, bi- and triovular follicles being common. Such follicles 

 apparently present the possibilities for ordinary twinning and multiple 

 births. Arnold (Anat. Rec., 6, 11, 1912) records follicles in the ovary 

 of a negress also with from four to ten oocytes, and one each with eleven 

 and thirteen oocytes. 



The following table is offered for the benefit of the student as a 

 resume of the several structural layers of the ripe Graafian follicle. The 

 structures are enumerated in order from without inward : 



f tunica externa 



1. Theca folliculi J tunica interna 



[membrana propria. 



2. Stratum (seu membrana) granulosum. 



3. Liquor folliculi occupying the antrum folliculi. 



4. Discus proligerus cumulus oophorus. 



5. Corona radiata. 



6. Zona pellucida (seu striata). 



7. Perivitelline space (possibly an artifact). 



8. Vitelline membrane. 



9. Vitellus egg cytoplasm. 



10. Nucleus or germinal vesicle. 



11. Nucleolus or germinal spot. 



The Corpus Luteum. The rupture of the follicle is accompanied 

 by sudden relief of the intrafollicular tension and consequent hemorrhage 

 from the thin-walled capillaries of the theca folliculi. Thus the cavity 

 of the follicle is filled with blood; the ruptured follicle is then known 

 as a corpus hemorrhagicum. This is the first stage in the formation of 

 the corpus luteum. 



Promptly succeeding the formation of the corpus hemorrhagicum,, 

 lutein cells appear at the periphery of the body. They are large, ovoid 

 or polyhedral cells having a clear finely granular cytoplasm and a peculiar 

 yellow color due to the presence of a pigment known as lutein. More- 

 over, the cytoplasm of the lutein cells becomes very rapidly infiltrated 

 with droplets of fat, likewise deeply colored by the lutein pigment which 

 33 



