Till: KKTAI. MEMBRANES OF MAN. 263 



shallow compartments by finer connect! ve-tissue from 



tin- membrane and the septa. 



The edges of the septa do not reach to the roots of the villi in 

 the middle of the placenta, hut only in a narrow peripheral region, 

 where they come into immediate contact with tin- membrami chorii 

 (Plate JI. //<), and are joined together nnderneat h it into a thin, 

 closely applied membrane, which is pierced by the roots of the villi. 

 This has been called by WINK I.I:K cA/x///y /,/*// ( Schluplatte, SP), 

 by KOI.I.IKKK decidua placentalis suhchorialis. Still more appro 

 priate is the term employed by WALDEYER, subchorial terminal ring 

 (Sclilus-rini:), because it is thereby stated that the membrane in 

 ([notion is present only at the margin of the placenta, leaving the 

 middle area of the chorion free. 



The connective-tissue framework of the placenta nterina {Assesses 

 in general the properties of the compact, abundantly cellular . 

 of the decidua vera and reflexa, but exhibits one peculiarity in the 

 presence of a very special form of cells, the so-called giant celts. 

 are large masses of protoplasm appearing yellowish ^rivy, and 

 with from ten to forty nuclei ; they begin to develop in the fifth mont h, 

 and are found in the after-birth in great numbers; they lie partly 

 in the ha.-al plate, partly in the septa, ordinarily in the immediate 

 vicinity of large blood-vessels; but they are also found isolated in 

 the spongy layer of the decidua serotina and even between the 

 adjacent muscle-bundles of the uterus. 



The greatest difficulties in the investigation of the placenta uterina 

 are caused by its blood-courses. Numerous spirally twisted arterial 

 Mems (Plate II. a) penetrate through the muscular layer of the womb, 

 and, passing through the spongy layer, reach the basal plate of the 

 placenta uterina, where their structure undergoes important changes. 

 For they here lose their muscular layer, and now appear as large 

 tubes, lined with endothelium only. From the basal plate they 

 penetrate in part into the septa placentae. From here they are 

 not to be followed further as closed vessel> \ * to capillaries 



does not take place aniin-1,,-,-,-. On the contrary, it can be proved that 

 through openings in the basal plate and the septa they pour their 

 blood into a system of cavities between the chorionic villi. /.<., into 

 the interriltoiiff or inti-<i/>l<t' ":es (c). The latter are bounded 



on the one side by the membra na chorii (in) with its villi (~), on tin- 

 the other side by the basal plate (/?/') with its septa. 



The blood is collected from this system of ea\ernous spaces into 

 large reins, which are likewise simply tubes lined with endothelium. 



