138 



The Endocrine Organs 



from the interstitial cells. It is from these theca cells that the cells of the 

 corpora lutea are derived ; while, on the other hand, as the latter disappear, 

 many of their cells tend to lose themselves in the substance of the stroma. 



The Corpora Lutea 

 The manner of development of the corpora lutea appears to be as 

 follows : — The larger follicles become gradually more distended with liquor 



folliculi, and ultimately 

 split open at the thinnest 

 and most prominent part. 

 When the follicle bursts, 

 the ovum and discus pro- 

 ligerus escape, and the 

 rest of the follicular epi- 

 thelium also becomes de- 

 tached from the follicular 

 wall and extruded or dis- 

 integrated. The cavity 

 of the follicle is now usu- 

 ally occupied by a blood- 

 clot (fig. 93), derived from 

 vessels at the point of rup • 

 ture of the follicle. The 

 enlarged cells in the wall 

 of the theca multiply and 

 grow into the cavity, dis- 

 placing the clot towards 

 the hilum of the follicle. 

 They are filled with lipoid 

 droplets which give the 

 structure the yellowish 

 colour from which the name corpus luteum is derived. The cells are now 

 known as luteal cells ; in most animals they arrange themselves in trabecule 

 converging towards the remains of the clot (figs. 94, 95), which becomes 

 gradually organised, its place being taken by fibrous or cicatricial tissue. 

 Sinus-like blood-vessels grow in from the theca along with the luteal 

 cells, and the whole structure eventually forms, in most animals, a solid 

 gland-like vascular mass, which is usually much larger than the follicle it 

 replaces. In animals which have several young at a birth, and in which 

 therefore several follicles come to maturity at about the same time, the 

 resulting corpora lutea may appear to occupy almost the whole ovary, 

 which becomes greatly enlarged as they develop. 



From the above account, which is based upon observations in the rabbit and 

 corresponds with that originally furnished by von Baer, since confirmed by many 



Fig 94.— A stage in the development of a corpus luteum of 

 the rabbit in which the cells form trabecule converging 

 towards the remains of the blood-clot which originally 

 occupied the cavity of the Graafian follicle. Magnified 

 60 diameters. 



