PLACENTA 



79 



loculi. The villi are clothed by a thin layer of continuous protoplasm in which 

 nuclei are regularly arranged (figs. 105 and 108), and many of them have a 

 layer of fibrinous material under this syncytium. In the outer part of the 

 placenta the syncytial layer has in large measure disappeared, to be replaced 

 by a thick mass of fibrin, and many of the stems have undergone complete 

 fibrinous degeneration (fig. 108). A dense layer of the same substance also occupies 

 the outer part of the remnant of the decidua basalis adhering to the placenta. 

 The blood enters the intervillous space by afferent vessels in the decidua 



1 o oo ,aAtf . o & ooos& oV> ^2 W\ .0. ./ *% I o o o o 



oo*oo> - 



o O 



FIG. 108. SECTION THROUGH A PLACENTA AT FULL TIME.J V (T. H. Bryce.) 



The intervillous space is represented filled with maternal blood. The foetal capillaries were 

 injected by stripping back the umbilical cord before it was tied, and the corpuscles are represented 

 solid to distinguish them from the maternal. Notice the layer of syncytium on the villi ; under it, in 

 many villi, there is a layer of fibrinous material represented by a continuous line; F is a large villus 

 which has undergone fibrinous degeneration. (From a preparation by Dr. J. H. Teacher.) 



connected with small arteries which pursue a spiral course, and are hence 

 called the ' curling arteries,' while it leaves it by efferent vessels connected with 

 the veins in the deep part of the remnant of the decidua basalis. 1 



1 For the literature of the placenta, see Strahl in Hertwig's Handbuch, i. Teil I., II. p. 856 ; also 

 for some later papers, Kollmann's Handatlas, 1907, appendix, p. 35. See also J. Clarence Webster, 

 Human Placentation, Chicago, 1901 ; and for comparative data, Arthur Bobiuson (Hunterian 

 Lectures), Jour, of Anat. and Phys. vol. xxxviii. 



