896 



SPERM, OVA, AND PREGNANCY 



tlie basement membrane upon whicli the 

 Langhans cells or syncytium rest (Fig. 

 15.54 1 . 



Lipids. Birefringent, sudanophilic lipid 

 droplets are abundantly present in both the 

 inner and outer zones of the syncytium 

 (Figs. 15.6 and 15.13). The droplets are 

 acetone soluble. They react with phenyl- 

 hydrazine (Wislocki and Bennett, 1943), 

 give a positive Schiff reaction, exhibit yel- 

 lowish green fluorescence (Dempsey and 

 Wislocki, 1944; Rockenschaub, 1952), and 

 give a positive naphthoic acid-hydrazide re- 

 action (Fig. 15.18) (Ashbel and Seligman, 

 1949; Seligman, Ashbel and Cohen, 1951; 

 Wislocki, 1952; Ashbel and Hertig, 1952). 

 These histochemical reactions occur also in 

 the lipid droplets of the gonads and adrenal 

 cortex, and their occurrence in the syncy- 

 tium suggests that it is the site of steroid 

 hormonal synthesis in the placenta. Previ- 

 ous and later paragraphs discuss this prob- 

 lem more fully. 



Enzymes. Alkaline phosphatase (Figs. 

 15.4, 15.41, and 15.42) occurs in the syncy- 

 tial trophoblast (Buno and Curi, 1945), 

 where it is slight in amount at 6 weeks, 

 but it increases tremendously as gestation 



advances (Dempsey and Wislocki, 1945). 

 It varies in degree of activity according to 

 the substrate used, the enzymatic reaction 

 being most intense following the use of 

 fructose diphosphate and nucleic acid, and 

 less so with glycerophosphate and adenylic 

 acid (Dempsey and Wislocki, 1947). The 

 reaction occurs earliest and reaches its 

 maximal intensity in the brush border, al- 

 though, as gestation proceeds, it spreads 

 throughout the syncytial cytoplasm and 

 also involves the nuclei. However, the lo- 

 calization of the enzymatic reaction within 

 the nuclei may not represent the actual dis- 

 tribution in the living state, for investiga- 

 tions have shown that the reaction products 

 are capable of migrating, especially from cy- 

 toplasm to nuclei (Martin and Jacoby, 1949; 

 Leduc and Dempsey, 1951 ; Herman and 

 Deane, 1953). This enzyme is a distinguish- 

 ing feature of the great absorptive surfaces 

 of the small intestine, proximal convoluted 

 tubule of the kidney, and syncytial tropho- 

 blast of the placenta. 



Acid phosphatase (Figs. 15.39 and 15.40) 

 occurs in great intensity in the syncytium 

 in both cytoplasm and nuclei (Wislocki and 

 Dempsey, 1948). The nuclear staining may 



Plate 15. V 



All of the drawings on tliis i)late (except Fig. 15.23) are of frozen sections of material fixed 

 in 10 jier cent l^uffered formalin and stained by the Ashbel and Seligman method for car- 

 bonyl groups. Comi^are the illustrations on this plate with those on Plate 15.IV. 



Fig. 15.18. The syncytial trophoblast of a human villus at 5 months of gestation, stained 

 by the carbonyl method. The reaction is localized in the lipid droplets of the syncytium. Com- 

 pare with Figure 15.13. X 7 ocular; X 90 objective. 



Fig. 15.19. A human placental villus at full term illustrating the positive carbonyl reaction 

 of the minute lipid droplets in the syncytium as well as a diffuse reaction of the entire syncy- 

 tial cytoplasm. Compare with Figure 15.14. X 7 ocular; X 60 objective. 



Fig. 15.20. The placental labyrinth of a cat (fetal crown to rump length, 75 mm.) showing 

 an intense carbonyl reaction in lipid droplets located in the cytotrophoblasts of the placental 

 lamellae. A diffuse lavender reaction is present in the contiguous trophoblastic syncytium. 

 X 10 ocular; X 40 objective. 



Fig. 15.21. The carbonyl reaction in the placenta of a rat of 18 days of gestation. Compare 

 with Figure 15.16 illustrating the distribution of sudanophilic lipids in the rat's placenta, and 

 with Figure 15.17 illustrating the carbonyl reaction in the labyrinth of the mouse. X 10 ocular; 

 X 40 objective. 



Fig. 15.22. The carbonyl reaction in the placenta of a pig (crown to rump length, 90 mm.). 

 The reaction is localized in the uterine epithelium, whereas little staining is apparent in the 

 chorion. The distribution of the reaction coincides with that of lipids revealed by sudan dyes 

 (Fig. 15.15). X 10 ocular; X 40 objective. 



Fig. 15.23. The placenta of a pig (fetal crown to rump length, 235 mm.). Bouin's fixation. 

 Masson's stain. This figure is shown to illustrate the detailed structure and relative thinness 

 of the pig's placental barrier. It shows "intra-epithelial" maternal capillaries {m.c.) in the 

 uterine epithelium (ep), and "intra-epithelial" fetal capillaries (/.c.) in the chorionic syncy- 

 tium (c/i) ; the distance separating the two sets of capillaries varies between 6 and 8 /x. Com- 

 pare with Figures 15.28 and 15.64 which also illustrate the extreme thinness of the trophoblast 

 and the narrow distance separating the maternal from the fetal capillaries in the placenta of 

 the pig. X 70 ocular; X 40 objective. 



