THE CORPUS LUTEUM. 



613 



FIG. 173. 



to such a degree that ovulation is arrested, and no more Graafian folli- 

 cles are ruptured, during the whole term of pregnancy. It is not sur- 

 prising that the growth of the corpus luteum should be modified from 

 the same cause. 



For the first three weeks of its formation the corpus luteum presents 

 the same features in the impregnated as in the unimpregnated condition. 

 But after that time a difference becomes manifest. Instead of commenc- 

 ing a retrograde course during the fourth week, it continues its develop- 

 ment. The external wall grows thicker and more convoluted. Its color 

 changes, as previously described, to a bright yellow ; and it contains a 

 deposit of fatty matter in the form of microscopic globules. 



By the end of the second month of pregnancy, the corpus luteum has 

 increased to 22 millimetres in length by 12 or 13 millimetres in depth. 

 The central coagulum has be- 

 come nearly decolorized, and 

 presents the appearance of a 

 fibrinous deposit. Sometimes 

 a part of the serum, as it sepa- 

 rates from the clot, accumulates 

 in the centre of the mass, as in 

 Fig. 173, forming a little cav- 

 ity filled with clear fluid and 

 inclosed by a fibrinous layer, 

 the remains of the solid portion 

 of the clot. The existence of 

 such a cavity, however, is only 

 occasional. More frequently, the fibrinous clot is solid throughout, all 

 the serum being absorbed by the surrounding parts. 



During the third and fourth months, the enlargement of the corpus 

 luteum continues ; and at the end 



of that time it may measure 22 F 10 - 174. 



millimetres in length by 18 or 19 

 millimetres in depth. Its flat- 

 tened form is very manifest, so 

 that, in a longitudinal section, it 

 may present a nearly circular out- 

 line, as in Fig. 174, while in a 

 transverse section its figure is 

 a narrow oval. The convoluted 

 wall is still more highly de- 

 veloped than before, having a 

 thickness, at its deepest part, of 

 nearly 5 millimetres. Its color, 

 however, has already begun to 

 fade, assuming a dull yellowish 

 tinge. The central coagulum, perfectly colorless and fibrinous, is often 

 so much flattened laterally that it is hardly 2 millimetres in thickness. 



CORPUS LUTEUM of pregnancy, at the end of the 

 second month; from a woman dead from induced 

 abortion. 



CORPUS LUTEUM of pregnancy, at the end of the 

 fourth month ; from a woman dead by poison. 



