25 o NORMAL HISTOLOGY. 



is termed the corpus luteum vernm. If impregnation does not occur, the yellow body, 

 now called the corpus luteum spit Hum, is smaller and seldom exceeds from 1.5-2 cm. 

 The classic distinction of "true" and "false" has no anatomical basis, since, apart 

 from size, both forms are structurally identical. The assumption, that the presence 

 of a large corpus luteum is proof of pregnancy, must be accepted with much caution, 

 since yellow bodies of unusual size are sometimes observed in ovaries of virgins. 

 With the production of a solid corpus luteum and the absorption of the blood, 

 evidences of the latter remaining for a long time as hematoidin crystals, the active 

 r61e of the lutein cells is finished. These elements now lose their yellow pigment 

 (lutein), undergo fatty change and finally entirely disappear. The connective tissue 

 which now constitutes the entire mass, undergoes hyaline change, becoming clear 

 and nonfibrous, while the aging corpus luteum loses its former appearance and is 



Meso- 

 Blood-vessels salpinx Broad ligament 



Corpus luteum 

 Corpora Iv.tea 



Mesovarium ^ r ". " 



Cortex 

 Graafian follicles 



' . 



Sections of oviduct 

 Medulla 

 Remains of corpora lutea 



FIG. 300. Cross-section through ovary, oviduct and part of broad ligament. X 4. 



transformed into an irregular body, light in color and sinuous in outline, sometimes 

 termed the corpus albicans. The corpus luteum is now regarded as an organ of inter- 

 nal secretion, which produces a stimulant of the uterine mucosa, for the formation of 

 the deciduae, and of the mammary gland. 



The Medulla. The vascular central zone of the ovary, the medulla, 

 consists of comparatively loose stroma-tissue, composed of irregularly felted 

 bundles of fibrous tissue rich in elastic fibres, supporting the vessels and 

 nerves. In the mature ovary, with the exception of occasional encroaching 

 Graafian follicles that are ripening, egg-sacs are not found within the medulla. 

 On the other hand, it contains many blood-vessels some of which, when seen 

 in cross-section, may be mistaken by the inexperienced observer for sections 

 of follicles. The larger vessels are surrounded by considerable tracts of 

 involuntary muscle, which are continuous in part with those of the utero- 

 ovarian ligament, through the hilum and mesovarium, the fold of peritoneum 

 which attaches the ovary to the broad ligament. The veins are particularly 

 large and appear in sections as huge blood-spaces of irregular outline, in 

 consequence of their tortuosity and plexiform arrangement. 



The blood-vessels supplying the ovary are four or five branches from 

 the anastomotic arch formed by the ovarian and uterine arteries. These 

 branches, the arteria propriee, reach the medulla through the hilum as closely 

 grouped tortuous vessels. On gaining the interior of the ovary, each stem 

 divides into two medullary or parallel arteries that proceed directly towards 

 the opposite free margin of the organ, lying just beneath the cortex to which 



