1386 Journal of Applied Microscopy 



Burckhard, Q. Die Implantation des Ei der It was the purpose of this investigation 

 Mans in die Uterusschleinihaut und die Um- , ,, ■ i ■ i 



bildungderselben zur Decidua.Arch.f. Mik. to toUow the changes in the uterus 

 Anat. u. Entwick, 57: 528-569, Taf. 26-28, from the time the egg enters it from 



the oviduct until the embryo is fully 

 encapsuled in its walls in the so-called decidua rejfcxa. About the beginning of 

 the fifth day after impregnation in the mouse, the ova are clustered at the lower 

 end of the oviduct in an advanced stage of cleavage with a small cleavage cavity 

 appearing. About this time they enter the uterus and are immediately distrib- 

 uted, probably by movements of the uterine walls, at somewhat regular intervals 

 throughout the uterine lumen, lying in crypt-like depressions on the antimeso- 

 metrial side of the lumen. The process of implantation is completed by the 

 eighth day and, owing to the rapidity with which it takes place, has been over- 

 looked in large part by all previous investigators of the subject. At the end of 

 the eighth day the embryo is separated from the lumen and embedded in the 

 decidua, composed entirely of mucosa cells from which all traces of the uterine 

 epithelium have disappeared. Other investigators have suggested that the embryo 

 sinks beneath the epithelium and develops in the mucosa, but Burckhard's 

 results show conclusively that this position of the embryo is brought about by a 

 degeneration of the uterine epithelium of the walls adjacent to the embryo. By 

 the middle of the fifth day the epithelium near, but not as yet in contact with, the 

 ovum, shows traces of flattening and the cells of the subjacent mucosa exhibit 

 nuclear activity. Eosinophilous leucocytes invade this territory and the capil- 

 laries branch and spread toward the region of the ovum, while the uterine glands 

 close and degenerate from the uterine lumen toward the musculature. By 

 the middle of the sixth day the epithelium near the ovum (lining of the decidual 

 cavity) is much flattened and the walls on the mesometrial side meet above the 

 ovum uniting with its ectoplacental one (Trager), thus completely separating the 

 decidual cavity from the uterine tract. By this time the epithelium near the 

 ovum has disappeared entirely either by degeneration or retraction, while the 

 remainder of the lining of the decidual cavity degenerates by evident desquama- 

 tion and karyolysis. 



The ovum now lies in the uterine mucosa beneath the epithelium on the 

 antimesometrial side of the uterus. Multiplication of the decidual cells and 

 their subsequent growth, combined with increased vascular supply, result in 

 further closure of the uterine walls above the ovum until only a small lumen 

 remains. The thickened vascular region above the ovum becomes the placenta, 

 while the persistent lumen, now on the mesometrial side of the ovum, comes at a 

 later stage to lie on the antimesometrial side. The manner in which the change 

 is accomplished is not at present known. The probability of a method of implan- 

 tation of the ovum in the human uterus similar to that found in the mouse is 

 suggested and discussed at length. The material examined was secured entirely 

 from white mice. The uteri were removed immediately after death to picro-subli- 

 mate, Zenker's, Flemming's or Hermann's fluids for twenty-four hours. Safranin 

 iron-hsmatoxylin was used after the last two fluids, borax carmin or 

 haematoxylin-eosin after the other fluids. These last preparations gave 

 the best results ; since the eosin differentiates the blood corpuscles and also 

 gives the epithelium of the uterus and its glands a characteristic tint. The 

 figures illustrating this paper are very fine, being based upon micro photographs 

 prepared by Sobotta's method. c. a. k. 



