15 



HISTOCHEMISTRY AND ELECTRON 

 MICROSCOPY OF THE PLACENTA 



George B. Wislocki, M.D., Sc.D. (Hon.) 



LATP: JAMES STILLMA.N PROFESSOR OF COMPARATIVE ANATOMY 

 AND HERSEY PROFESSOR OF ANATOMY 



and 

 Helen A. Padykula, Ph.D. 



ASSISTANT PROFESSOR OF ANATOMY, 

 HARVARD MEDICAL SCHOOL, BOSTON, MASSACHUSETTS 



I. Lntroduction 884 



II. HiSTOCHEMICAL METHODS UTILIZED IN 



THE Study of the Placenta 888 



A. Basophilia and Acidophilia 888 



B. Carbohydrates 889 



C. Lipids 889 



D. Enzymes 890 



E. Iron and Sulfhydryl and Amino 



Groups of Proteins 891 



III. The Placentas of Man and Rhesus 



Monkey 891 



A. Topography and General Histology. 891 



B. Chorionic Villi '. . 894 



1. Trophoblasts: the Langhans cells. 894 



2. Trophoblastic syncytium in the 



first and second trimesters of 

 l)regnancy 894 



3. Stroma of the chorionic villi; 



Hofbauer cells 897 



4. Age changes in the chorionic villi . 898 



C. Peripheral Cytotrophoblast 902 



1. Trophoblasts forming the cell 



columns and trophoblastic shell 903 



2. Ground substance of the tropho- 



blastic cell columns and shell. 904 



3. Cytotrophoblast of the basal 



plate and septa placentas at 

 term 904 ' 



4. Cytological comparisons of the 



cytotrophoblasts with decidual 

 cells 905 



5. Cytolytic and proteolytic activi- 



ties of peripheral trophoblasts. 905 



IV. The Structure of the Placental 



Barrier 908 



A. Grosser's Classification 908 



B. Ultrastructure of the Chorio-allan- 



toic Placenta 909 



C. Reduction in the Number of the 



Layers of the Chorio-allantoic 

 Placenta 914 



D. Reduction in Width of the Layers 



of the Chorio-allantoic Placenta. 914 



V. Yolk Sac Placentation 917 



VI. Histochemistry with Reference to 



Comparative Placentation 922 



A. Lipids 923 



B. Glycogen and Carbohydrate Con- 



taining Macromolecules 926 



C. Metachromasia 927 



I). Phosphatases 927 



VII. Evidence of the Possible Site of 

 Production of Placental Steroid 



Hormones 930 



VIII. Evidence of the Possible Site of 

 Production of Gonadotrophic 



Hormones 931 



IX. Significance and Relationships of 



Some Placental Constituents .... 937 



A. Ribonucleoprotein 937 



B. Alkaline Phosphatase 938 



C. Alkaline Phosjjhatase and the Peri- 



odic Acid-Schiff Reaction 940 



D. Relationship of Lipids to the Pla- 



cental Barrier 942 



E. Fibrinoid 942 



X. Placental Permeability with Re- 

 spect to Morphologic Type 943 



XL Summarizing Reflections on Com- 

 parative Placentation and Pla- 

 cental Permeability 947 



XII. References 950 



883 



