124 PRACTICAL HISTOLOGY. 



THE FCETAL MEMBRANES. 



THE DECIDUA. 



THE decidua vera and reflexa can be separated from each other near the placenta. 

 Remove a little of the tissue from the outer surface of the decidua reflexa, and examine it in 

 salt solution. It will be found to be nearly covered with fusiform cells, which are, for the 

 most part, filled with fatty particles. These cells may be stained with methyl-aniline, and 

 preserved in a saturated solution of acetate of potash. 



The substance of the decidua consists of a tissue closely resembling mucous tissue. If a 

 small piece be treated with gold chloride (p. xlv) branched connective-tissue corpuscles are 

 obtained. 



THE AMNION. 



A. small piece of this membrane, after being hardened for five days in Miiller's fluid, is 

 thoroughly washed, and placed on a slide, and stained with picrocarmine. Observe on its 

 inner surface a layer of somewhat flattened cells. 



THE UMBILICAL CORD. 



PREPARATION. Cut a fresh cord into pieces an inch in length, and harden them in 

 Miiller's fluid for two days, and afterwards in the chromic acid and spirit mixture for a week. 

 Make transverse sections. Stain one with logwood, and mount it in dammar, and another 

 with picrocarmine, and mount it in Farrant's solution. 



EXAMINATION (L). Observe the circular shape of the cord, containing sections of three 

 blood-vessels, i.e. two umbilical arteries and a larger umbilical vein. These are surrounded by 

 a modified mucous tissue (p. 28), called Wharton's jelly, and outside all is a layer of thin, 

 nucleated, polygonal cells. The tissue is denser around the blood-vessels. In Wharton's jelly 

 are found spaces the sections of canals that run in the cord. They are most obvious near 

 the circumference. Note the mucous corpuscles amongst the fibres. (Indicate the umbilical 

 arteries and vein, and Wharton's jelly, in PI. XXX., Fig. 5.) 



(H). Examine the walls of the arteries and vein, and note their great thickness. Study 

 the branched corpuscles of Wharton's jelly. (Indicate the spaces and the mucous tissue in PL 

 XXX., Fig. 6.) 



