54: THE STRUCTURE OF THE HUMAN PLACENTA. 



and other varieties of loops exist in the club-shaped and tube- 

 rose villi.* 



Lastly, It must be stated as a fact first recorded and re- 

 presented by Professor Weber, confirmed by the observations 

 of Mr. John Dalrymple, and to the accuracy of which I can 

 testify, that the same peculiar vessel, or umbilical capillary, 

 may enter and retire from two or more villi before it becomes 

 continuous with a vein. 



6. Of the internal Cells of the Villas. 



Within the internal membrane, and on the external surface 

 of the umbilical capillaries, are cells which I have named 

 the internal cells of the tuft. When the vessels are engorged, 

 these cells are seen with difficulty. When the vessels are 

 moderately distended, and the internal membrane separated 

 from the external cells by moderate pressure, the cells now un- 

 der consideration come into view. They are best seen in the 

 spaces left between the internal membrane and the retiring 

 angles formed by the coils and loops of the vessels, and in the 

 vacant spaces formed by these loops. These cells are egg-shaped, 

 highly transparent, and are defined by the instrument with dif- 

 ficulty ; but their nuclei are easily perceived. They appear to 

 be filled with a transparent highly refractive matter. This 

 system of cells fills the whole space which intervenes between 

 the internal membrane of the villus and the vessels, and gives 

 to this part of the organ a mottled appearance. 



* Mr. Dalrymple, in his Paper on the Placenta, in the Med. Chir. Trans., has described 

 with great accuracy the manner in which the foetal vessels ramify and coil in the tufts of 

 the placenta. I am indebted to Mr. Dalrymple for specimens of his injections of the pla- 

 centa; and to Dr. John Reid, for a portion of a placenta injected by Professor Weber of 

 Leipsic, and have satisfied myself of the accuracy of the descriptions given by these 

 anatomists. My own observations have been made on the unprepared placenta. The 

 drawings of the foetal vessels in Dr. Reid s Paper are plans, as the only point he was anxious 

 to establish was, that the villi terminated in blunt extremities unconnected by cellular or 

 other textures, the foetal vessels returning upon themselves. REIO, in Edinburgh Medical 

 and Surgical Journal. 



