904 



SPERM, OVA, AND PREGNANCY 



genase activity is demonstrable by the for- 

 mation of blue formazan crystals in the 

 cytoplasm (Fig. 15.38). The cytotropho- 

 blasts contain little acid and alkaline phos- 

 phatase (Dempsey and Wislocki, 1947). 



From the observations cited above, it is 

 apparent that the peripheral trophoblasts 

 differ cytologically in several significant re- 

 spects from the Langhans cells of the cho- 

 rionic villi (Wislocki, Dempsey and Faw- 

 cett, 1948). The latter are chromophobic, 

 whereas the peripheral trophoblasts are dis- 

 tinctly chromophilic, exhibiting marked cy- 

 toplasmic basophilia and containing a dia- 

 stase-resistant polysaccharide. 



2. Ground Substance of the Trophoblastic 

 Cell Columns and Shell 



The nature of the ground substance (Figs. 

 15.12, 15.44, 15.45, 15.46, 15.47, 15.48, 15.49 

 and 15.55) lying between the peripheral 

 trophoblasts has not been clearly estab- 

 lished. Grosser (1925a, b) designated it "fi- 

 brinoid" and regarded it as a secretion of the 

 trophoblastic cells which becomes variously 

 admixed with fibrin of maternal origin. He 

 observed that the fibrinoid substance stained 

 blue with Mallory's connective tissue stain 

 in contrast to the fibrin which was stained 

 red. Spanner (1935a) concurred, stressing 

 that the ground substance surrounding the 

 trophoblasts does not contain a collagenous 

 reticular network, in this respect differing 

 from the matrix of the maternal decidua 

 basalis which possesses well defined retic- 

 ular fibers surrounding its cells (Fig. 15.27). 

 Wislocki and Bennett ( 1943) concluded that 

 the ground substance of the trophoblastic 

 shell and cell columns is probably a mixture 

 of maternal and fetal substances. They 

 pointed out that with other triacid stains, 

 such as Heidenhain's azan and Masson's 

 stain, fibrin is distinguishable from the 

 component which Grosser termed "fibri- 

 noid." The ground substance is also stained 

 by basic dyes (Fig. 15.11), but, unlike the 

 cytoplasmic basophilia of the trophoblasts, 

 that of the ground substance is not influ- 

 enced by exposure to ribonuclease (Fig. 

 15.12). However, Singer and Wislocki 

 (1948) were unable to distinguish two sep- 

 arate components on the basis of the affin- 

 ity of the ground substance for methylene 



blue and orange G as measured under con- 

 ditions of controlled pH staining; under 

 these conditions the reactions to both dyes 

 were found to be similar to that of purified 

 fibrin. On the other hand, PAS reagents 

 stain the fibrin an intense scarlet (Fig. 

 15.55), whereas the "fibrinoid" component 

 assumes a much paler color (Fig. 15.32), a 

 result which again indicates a distinct dif- 

 ference between them. Acid and alkaline 

 phosphatases are present only in traces. The 

 Turnbull blue reaction for iron occurs in- 

 tensely in the ground substance (Dempsey 

 and Wislocki, 1944). 



It is noteworthy that the ground sub- 

 stance of the peripheral trophoblast is nei- 

 ther metachromatic (Fig. 15.58) nor pro- 

 vided with argyrophilic reticular fibers 

 (Fig. 15.27) (Wislocki and Dempsey, 1948). 

 Thus, although fibrin of maternal origin 

 appears to gain ready access to the ground 

 substance of the cytotrophoblast, the meta- 

 chromatic component of the decidua as 

 such does not appear to diffuse into the 

 troj^hoblastic shell. 



3. Cytotrophoblast of the Basal Plate and 

 Septa Placentae at Term 



It is generally believed that the periph- 

 eral trophoblast undergoes regression and 

 degeneration in the second half of gestation, 

 no longer playing any significant functional 

 role. Spanner (1935a) states that the septa 

 consist of fibrinoid, containing lacunae from 

 which the trophoblastic cells gradually dis- 

 appear. Baker, Hook and Severinghaus 

 (1944) maintained that both cell columns 

 and cell islands are characteristic of early 

 pregnancy, the former persisting as late as 

 3.5 months. Furthermore, according to them, 

 some cells continue to show indications of 

 secretory activity, but for the most part 

 they degenerate into fibrinoid. Similarly, 

 Grosser (1948) remarked that the basal 

 plate in the ripe placenta is clothed on its 

 fetal side with trophoblastic cells in various 

 states of regression. 



The results obtained by the use of histo- 

 chemical methods differ in two major re- 

 spects from the views expressed above. 

 First, the occurrence of cytoplasmic baso- 

 philia, of a positive PAS reaction (Figs. 

 15.49 and 15.55), and of numerous mito- 



