896 



OF GENERATION ACTION OF THE FEMALE. 



FIG. :m. 





undergoes a considerable change. Its walls become more vascular externally, 

 and are thickened on their interior by the deposit of a fleshy-looking sub- 

 stance, which in many of the lower 

 Mammalia is of a reddish color, whilst 

 in the Human female it is rather of a 

 yellowish hue. This substance, known 

 as the Corpus luteum, is at first entirely 

 composed of an aggregation of cells 

 (Fig. 313), and may, in fact, be con- 

 sidered as an increased development, 

 or hypertrophy, of the " membrana 

 granulosa" or epithelial lining of the 



ovsac; many of its cells, however, 

 especially those in apposition with the 

 enveloping wall of the follicle, undergo 

 a more or less complete transformation 

 into fibres; and thus a gradual transition is established between the cellular 

 substance of the interior of the mass, and the fibrous strorua of the Ovarium 

 itselt. 1 In most domestic quadrupeds, this growth, which sprouts like a mass 

 of granulations from the lining of the ovisac, is often so abundant, if the 

 ovurn be impregnated, as not only to fill the cavity of the ruptured vesicle, 

 but even to protrude from the orifice on the surface of the ovary ; this orifice 

 subsequently closes, and the contained growth becomes gradually firmer, its 

 color changing from red to yellow. In the Human female, however, as in 

 the Sow, this new formation is at first less abundant ; it does not form mam- 

 millary projections from the interior of the ovisac, but lies as a uniform layer 



Cells forming the original substance of the 

 Corpus Luteum. 



FIG. 314. 



9 h 



Successive stages of the formation of the Corpus Luteum, in the Graafiau follicle of the Sow, as seen 

 in vertical section : at a is shown thy state of the follicle immediately after the expulsion of the ovum, 

 its cavity being filled with blood, and no ostensible increase of its epithelial lining having yet taken 

 place ; at h, a thickening of this lining has become apparent ; at <; it begins to present ('..Ids which are 

 deepened at d, and the clot of blood is absorbed paripassu, and at the same time decolorized ; a con- 

 tinuance of the same process, as shown at e,f, g, h, forms the Corpus Luteuin, with its stellate cicatrix. 



upon its lining; and this is thrown into wrinkles or folds, in consequence of 

 the contraction of the ovisac (Fig. 314, a d). An irregular cavity is thus 

 at first left in the interior of the ovisac, after the discharge of the ovum ; but 



1 By some observers, as Kolliker, the principal part of the new growth is regarded 

 as thr rou It. of a hypertrophy of the internal layer of the fibrous membrane of the 

 original follicle, which, even before the expulsion of the ovum, becomes loosened in 

 tcxtun- and augmented in thickness. The fact seems to be, that, as in the case of the 

 JMalpighian bodies of the Spleen (g 212, fii), there is no distinct line of demarcation 

 between ihe fibrous loall and the cdltitur contents of the follicle. 



