164 
A Preliminary Note upon the Question of the Nutrition of the 
karly Embryo, with Special Reference to the Guinea-pig 
and Man. 
By E. Emrys-Roserts, M.B. (Liverpool), Ethel Boyce Research Fellow in 
Gynecological Pathology in The University of Liverpool. 
(Communicated by Professor C. S. Sherrington, F.R.S. Received February 20,— 
Read March 16, 1905.) 
During the progress of a research into the earliest implantation of the 
embryo of the guinea-pig, | have been particularly struck with the way in 
which the nutrition of the embryo is anticipated and provided for during the 
time it remains free in the uterine horn. The so-called yolk-granules of the 
ovum are obviously insufficient to provide for the growth of the embryo to 
the stage prior to differentiation of the inner cell-mass, to which it attains 
during the five or six days which elapse before it comes into contact with the 
maternal tissues.* It is clear that it must derive nourishment from the 
medium in which it ihes—the product of the secretion of the uterine or other 
glands, which, during the period of pro-cestrum, exhibit such marked activity. 
I suggest that this secretion, which consists of mucus and probably albumin, 
is assimilated by the embryo after having undergone a process of digestion, 
the result of a secretory activity on the part of the outermost cells of the 
embryo—the cells of the Trophoblast. This suggestion I base on my 
observations in the guinea-pig, where I am able to demonstrate a breaking- 
down of maternal cells before the Trophoblastic cells are in actual contact ; 
likewise in human placentation where a more or less dense layer of fibrin and 
broken-down leucocytes and decidual cells, the result of Trophoblastic activity, 
affords a barrier interposed between the invading Trophoblastic cells and the 
Decidua. This layer 1 purpose naming the “ Protective Layer.” 
Looked at from a comparative point of view, there is in all probability a 
close analogy between the uterine secretion of mammals, and the secretion of 
the oviducts of the lower vertebrata. In the case of birds the analogy is very 
striking, on account of the direct and important share in the nutrition of the 
embryo afforded by this secretion, commonly known as the white of the egg. 
In the case of the frog the ovum receives in its passage down the oviduct, 
corresponding to the uterine horn of the guinea-pig, a coating of mucus and 
* This insufficiency is even more pronounced in the mole, where the uterine cavity is 
actually distended by the growing embryo before implantation takes place. 
