964 OF GENERATION. 



lining; and this is thrown into wrinkles or folds, in consequence of the con- 

 traction of the ovisac. An irregular cavity is thus at first left in the interior 

 of the ovisac, after the discharge of the ovum ; but this gradually diminishes, 

 partly in consequence of the increased growth of the yellow substance, and 

 partly owing to the general contraction of the ovisac, until it is at last nearly 

 obliterated or reduced to a sort of stellate cicatrix. An effusion of blood fre- 



Fig. 245. 



Successive stages of the formation of the Corpus Luteum, in the Graafian follicle of the Sow, as seen in ver- 

 tical section : at a is shown the 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 b, a thick- 

 ening of this lining has become apparent : at c, it begins to present folds which are deepened at d, and the 

 dot of blood is absorbed pari passu, and at the same time decolorized ; a continuance of the same process, as 

 shown at e,f, g, h, forms the complete Corpus Luteum, with its stellate cicatrix. 



quently takes place into this cavity, in the Human female, at the time of the 

 rupture of the ovisac; but the coagulum which is left takes no share in the 

 formation of the } 7 ellow body. It generally loses its coloring matter, and ac- 

 quires the characters of a fibrinous clot; and this may either form a sort of 

 membranous sac, lining the cavity, or it may become a solid mass, occupying 

 the centre of the stellate cicatrix. 



970. The cells which line the Graafian follicle undergo a great increase 

 of size at the time of the discharge of the ovule, and are also partially meta- 

 morphosed into fibres, especially where they come into apposition with the 

 enveloping wall of the follicle; in fact, a gradual transition may be traced 

 between the cellular substance of the interior of the follicle, and the fibrous 

 stroma of the Ovarium itself. In this manner is formed that reddish-yellow 

 granulation-like substance, friable in consistence, and very vascular, which oc- 

 cupies that part of the ovary of a pregnant female whence the ovum has been 

 discharged, and is known under the name of the Corpus Luteum. Its size varies 

 according to the length of time which has elapsed since conception. At first, 

 it is usually so large as to occasion a considerable projection on the surface of 

 the ovary ; its form is oval, or resembles that of a bean. When cut across, its 

 dimensions are usually found to be from 4 to 5-8 ths of an inch in its long 

 diameter, and 'from 3 to 4-8ths in its short ; and it thus occupies from a fourth 

 to a half of the whole area of the ovarium ; but these dimensions are not unfre- 

 quently exceeded. The centre^ of this substance is hollow ; and by a proper 

 acquaintance with this character, the true Corpus Luteum maybe distinguished 

 from substances bearing a general resemblance to it, but very different in their 

 character. The following is Dr. Montgomery's account of it : " Its centre ex- 

 hibits either a cavity, or a radiated or branching white line, according to the 

 period at which the examination is made (Fig. 246). If within the first three 

 or four months after conception, we shall, I believe, always find the cavity still 



