86 OBSTETRICAL PHYSIOLOGY. 



and development of the foetus by means of its intimate relations with 

 the uterine vascular system, until the time has arrived for the expulsion 

 of the young animal. Notwithstanding their close apposition, the 

 adherence of this papillary layer of the chorion with the inner surface 

 of the uterus is so slight, that this organ can scarcely be opened with- 

 out more or less destroying it. A small quantity of a brownish fluid is 

 found between the two. 



At an early stage of gestation there is no placenta ; a temporary mass 

 of albuminoid substance accumulating around the ovum in the uterus, 

 affords material for its nourishment until the vascular intussusceptive 

 relations between the chorion and uterine lining are established. When 

 gestation is terminated, the placenta becomes remarkably rigid, the 

 vessels are obliterated and transformed into fibrous tissue, and the 

 external face of the chorion is wrinkled and withered-looking. 



Differences. 

 Coic. 



In Euminants, there is an important difference in the arrangement of 

 the placenta from that just described. In the Cow the villi of the 

 chorion are developed and agglomerated in large numbers at certain 

 points of its surface, to constitute a multiple or tufted placenta, which 

 is composed in this way of from sixty to eighty placentidc2, or " foetal 

 cotyledons." These are of a bright red colour, of various sizes, and 

 generally oval in shape ; they correspond to the prominences on the 

 lining membrane of the uterus from which the deciduous maternal parts 

 of the placenta grow, and which have been already described as the 

 "maternal cotyledons" or "placentse"; into these latter the foetal 

 processes are received. The maternal cotyledons are nothing more, as 

 has been stated, than appendages or thickened points of the mucous 

 membrane, whose utricular follicles, more numerous than elsewhere, 

 have become enormously enlarged, and crypts have been formed. They 

 are permanent, as before conception they are certainly present on the 

 inner surface of the uterus, and traces of them may be already found in 

 the foetus of four or five months ; observation also appears to have 

 demonstrated that they may be increased in number, or regenerated, 

 when accidental circumstances render those in existence insufficient. ^ 

 They have been discovered in the foetus in process of formation, and 

 regularly disposed, beside the ordinary cotyledons. 



Ghauveau's experiments have proved, that after all these placentulae 

 have been extirpated from the uterus of the px'egnant Cow, sterility 

 does not necessarily follow ; but if, on the contrary, the animal sur- 

 vives the operation, it is still capable of breeding. In such circum- 

 stances, accessory cotyledons are developed upon the surface of the 

 uterine mucous membrane, where previously none existed. Chauveau 

 has also stated that during pregnancy the number of cotyledons is 

 increased ; and Colin, in his Plii/siologie Comparec, makes a similar 

 statement. Professor Franck, of Munich, in his dissections of the 

 gravid uterus of bovines, has found, in a large number of instances, 

 a more or less abundant quantity of accessory caruncles [harunkeln) on 

 the mucous membrane, and which had no corresponding relations with 

 the chorion. In one instance the ordinary cotyledons were entirely 



' In the Journal de Med. Veterinaire de Lyon, M. Strebel, of La Tour, Switzerland, 

 gives an instance in which there was absence of the uterine cotyledons in a Cow, and the 

 placenta was like that of the Mare. Conception took place, gestation went on favourably, 

 and parturition was normal. 



