54 



OBSTETRICAL AX A TOMY. 



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 hnear figure 

 surrounded by the corpus luteum, which is ultimately absorbed, but 

 usually not before some weeks after parturition. 



It is this difference between the impregnated and unimpregnated 

 condition which enables us to distinguish, in these ruptured vesicles, 

 the true and 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 

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



Fig. 34. 



Successive Stages in the roRiiATiox of the Corpus Ldteuii in the 

 Graafian Follicle of a Sow : Vertical Section. 



a, 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 6 a thickening of this lining has become apparent ; at c it 

 begins to present folds, which are deepened at d, and the clot of blood is 

 being absorbed and decolorised ; a continuation of the same process, as 

 shown at e,f, <j, h, forms the Corpses lutevm, with its stellate cicatrix. 



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 

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

 or uniparity 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. 



