SECRETORY FUNCTIONS IN HUMAN PLACENTA 549 



body. Both the large and small types of decidual cells cer- 

 tainly belong to the mother's side, and the secreted or broken- 

 up matter of the uterine glandular cells is at first probably 

 drained into the uterine cavity, to be absorbed by the mother's 

 side. And, on comparing the relations between the secretion of 

 these various cells, and the time of pregnancy we find that, in 

 general, the secretion is at its height in the first half of preg- 

 nancy, and especially in the early part of that period, whereas 

 in the second half of pregnancy it generally declines consid- 

 erably, it being possible to demonstrate it only for a certain 

 period in the stroma cells of villi, the cells of Langhans' islets, 

 and in the decidual cells. Below I will give this correlation 

 Avith a diagram. 



In short, it may be deduced that all the important tissue ele- 

 ments of the placenta and decidua, if looked at from the histo- 

 logical view-point, perform secreting functions. Pending fur- 

 ther investigations in all possible directions, it would be diffi- 

 cult to tell what significance these secretions thrown out of the 

 various cell groups have physiologically; however, since it is 

 evident that almost all of their secretions are internally rejected 

 and are taken in either by the mother's or by the fetal side, 

 it makes one feel that, either by the cooperation of certain 'hor- 

 mones' which should of necessity be contained in each kind of 

 secretions or by their contending actions, both the mother and 

 the fetus would enjoy an extremely delicate and special 

 physiological action. If that is so, it follows that the placenta 

 should contain a great variety of 'hormones,' and the kind 

 and quantity of 'hormones' contained should naturally differ 

 according to the period of pregnancy and the kind of tissues, 

 it being quite clear from the following chart that, speaking 

 generally, those that are found in the early part of pregnancy 

 should be comparatively numerous in kind and in abundance. 

 On the contrary, however, I could not find any important 

 secretions in the placenta which is well ripened. This is the 

 point to which I should like to call attention for the deliber- 

 ate consideration of all observers who are interested in the. 

 placental poison. 



JOURNAL OF MOKPHOLOGY, VOL. 35, NO. 3 



