494 PLACENTA. 



well as their remarkable size and enclosure in capsules, they 

 present a remarkable similarity to ganglion cells. 



The presence of smooth muscular fibres first described in the 

 placenta uterina by Ecker,* and subsequently by Kamenew,t 

 has been positively denied by all other inquirers. My own re- 

 searches demonstrate the presence of smooth muscular fibres 

 to be constant in the external layers of the placenta uterina. 

 The fibres are tolerably abundant, and are frequently ar- 

 ranged in a laminated manner in teased-out preparations, 

 which, in accordance with the recommendations of Jassinski, J 

 have been treated with hydrochloric acid; a distinct well- 

 defined rod-like nucleus may be shown to exist in many of the 

 cells. In addition a not inconsiderable number of fusiform 

 cells, the characters of which could not be more closely investi- 

 gated, are visible in the various layers of the placenta uterina. 



The processes of the placenta uterina, which like septa 

 bound the cotyledons, and frequently divide and branch, 

 penetrate deeply into the foetal part, without ever reaching, as 

 Kolliker has pointed out, the innermost part of the foetal por- 

 tion of the placenta. No direct passage of these processes into 

 the foetal tissue exists, but they cease at the periphery of 

 the cotyledons, so that in the centre of the secondary coty- 

 ledons (Kamenew) no maternal tissue occurs between the 

 villi. In the finer ramifications of these processes, which re- 

 semble fibrous tissue, (the cellular) elements of the placenta 

 uterina are but seldom found. 



In reference to the bloodvessels of the mature placenta, the 

 researches of Kolliker, VirchowJ and others have shown that 

 there is no plexus of capillaries between the arteries and 

 veins ; but that a communication between these two sets of 

 vessels is established by means of sinuous cavities. 



* Icones' Physiologicce. Explanation of Taf. xxviii. 



t Mikroskopische Untersuchungen der Blutgefasse des Muttertheils der 

 Placenta, (Researches on the bloodvessels of the maternal portion of the 

 placenta,) Medicinsky Westnik, 1864, No. 13. 



J Zur Lehre uber die Struktur der Placenta, Virchow's Archiv October 

 Heft, 1867. 



Ueber die Bildung der Placenta, Gesammelte Abhandlungen zur wissen- 

 schqftliche Medicin. 



