s« 



OBSTETRICAL ANATOMY. 



tions of the ruptured ovisacs give the ovary a pitted and furrowed 

 appearance in advanced life. 



If the expelled ovum be not impregnated, the changes of the ovisac into 

 the yellow convolute cavity, then into the depressed stellate cicatrix, occur 

 somewhat rapidly ; but if impregnation takes place, the maturation of 

 successional ova is delayed, and the first change in the ruptured ovisac 

 goes on to a greater extent, the corpus luteiim not becoming obliterated 

 for a comparatively long time. In this period the inner coat, or original 

 ovisac, is much thickened by a larger deposit of yellow oil-granules ; it 

 becomes more deeply plicated, is impacted into a yellowish mass, and 

 gains an adventitious white lining membrane, and it rarely happens that 

 the cavity is obliterated before full gestation. It is then, in the human 

 species, represented by a stellate linear figure surrounded by the corpus 

 luteum, which is ultimately absorbed, but usually not before some weeks 

 after parturition. 



Successive Stages in the Formation of the Corpus Luteum in the Graafian 



Follicle of a Sow : Vertical Section. 



a, Follicle immodiately 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 ^ a thickening i 



of this lining has become apparent ; at f it begins to present folds, which are deepened at d, 

 and the clot of blood is being absorbed and decolorized ; a continuation of the same 

 process, as shown at e,f,g, h, forms the Coypus Luteum, with its stellate cicatrix. 



It is this difference between the impregnated and unimpregnated con- 

 dition which enables us to distinguish, in these ruptured vesicles, the true 

 znd false corpora lutea. 



In the Mare the retrocession of the true corpus luteum is more rapid 

 than in the other domesticated animals, and it has not that deep yellow 

 color observed in the Cow ; but it is of a darker, dull reddish-brown hue, 

 and on section presents convolutions resembling those of the brain. When 

 recent, the corpus luteum of the Mare is voluminous, and drawn towards 

 the hilus of the ovary ; it has two layers, the internal being constituted 

 by a clot of blood the size of a small nut. 



Franck has convinced himself, hy post mortem examination of Mares, 

 of the possibility of ova being thrown off from the ovary during preg- 

 nancy. 



It is to be remarked that the number of ovisacs and ova which become 

 matured at each " rut " or " heat," depends upon the multiparity or uni- 

 parity of the species ; in the Mare and Cow there is usually only one, in 

 the Sheep and Goat one or two, in the Pig from four to a dozen, and in 

 the Bitch a variable number. 



