^30 



SPERM, OVA, AND PREGNANCY 



the trophoblast covering the chorionic ru- 

 gae, acid phosphatase activity is low or 

 completely absent. 



In the rat placenta the distribution of 

 phosphatase activity toward adenosine tri- 

 phosphate at alkaline pH has been de- 

 scribed by Padykula (1958a). 



VII. Evidence of the Possible Site 



of Production of Placental 



Steroid Hormones 



In the section on methods, a procedure 

 for characterizing lipids was outlined for 

 localizing the sites of the synthesis of ster- 

 oid hormones or their precursors in histo- 

 logic sections. It was pointed out that none 

 of the reactions involved in the procedure 

 is specific for the identification of ketoster- 

 oids, but lipids possessing all of the proper- 

 ties enumerated have been found solely in 

 those organs (adrenals, gonads, and pla- 

 centa) in which steroid hormones are known 

 to be produced. 



In formalin-fixed, frozen sections of hu- 

 man placenta, birefringent, sudanophilic 

 lipid droplets are abundantly present in the 

 syncytial trophoblast throughout gestation. 

 They are acetone soluble, react with 

 phenylhydrazine (Wislocki and Bennett, 

 1943), give a positive Schiff reaction, ex- 

 hibit yellowish-green fluorescence (Demp- 

 sey and Wislocki, 1944; Rockenshaub, 

 1952), and also react positively with the 

 Ashbel-Seligraan reagents for carbonyl 

 groups (Ashbel and Seligman, 1949; Selig- 

 man, Ashbel and Cohen, 1951; Wislocki, 

 1952; Ashbel and Hertig, 1952). The lipid 

 droplets diminish in size and relative abun- 

 dance as gestation advances, but are, never- 

 theless, still apparent in the syncytium at 

 full term (Wislocki and Bennett, 1943, 

 Figs. 10 and 11). The decrease in droplet 

 size with age may not necessarily indicate 

 a reduction of functional activity, for in 

 the adrenal cortex and ovaries a diminution 

 in the size of the lipid droplets accompanies 

 active secretion (Deane, Shaw and Greep, 

 1948; Barker, 1951). Furthermore, since 

 the total volume of the syncytium must 

 increase considerably as the placental villi 

 grow and branch, it seems reasonable to 

 assume that the absolute quantity of the 



lipids may not actually diminish. Thus, 

 there is possibly no discrepancy between 

 the increase in formation and excretion of 

 steroid compounds in the course of gesta- 

 tion and the total amount of lipids in the 

 syncytium at term. 



Strands of syncytium which penetrate 

 the trophoblastic shell and junctional zone 

 in the first trimester of pregnancy (Wislocki 

 and Bennett, 1943) and undergo degenera- 

 tion are probably responsible for the pres- 

 ence in these regions of occasional patches 

 of lipids giving these reactions. 



The uterine glandular epithelium con- 

 tains large sudanophilic droplets which are 

 not birefringent, but stain with Schiff's 

 reagent (Wislocki and Dempsey, 1945) 

 and give a hydrazide reaction (Ashbel and 

 Hertig, 1952). Wislocki and Dempsey 

 (1945j erroneously equated Schiff's reac- 

 tion with the "plasmal" reaction and specu- 

 lated on its possible significance. It now 

 seems more probable that Schiff's reagent, 

 under the conditions of fixation utilized by 

 them, reveals peroxides of unsaturated 

 lipids (Nicander, 1951). Ashbel and Hertig 

 (1952) attributed staining of the epithelium 

 of the endometrial glands by the carbonyl 

 procedure to "ketosteroids," a conclusion 

 which Atkinson, in a discussion of their pa- 

 per, found difficult to believe, since he ob- 

 served that all of the cellular elements of the 

 parietal decidua give a positive reaction 

 for carbonyl groups. This objection seems 

 valid, inasmuch as the hydrazide will react 

 with the oxidation products of unsaturated 

 groups. 



In mammals, other than man and the 

 rhesus monkey, the observations cited in a 

 previous section of this review indicate 

 that lipid reactions characteristic of steroid- 

 producing cells are also usually located in 

 some part of the trophoblast (cat, shrews, 

 bat, rodents) . However, the pig's placenta 

 is exceptional in that the sudanophilic lipid 

 droplets giving the Ashbel-Seligman and 

 Schiff reactions are located in the uterine 

 epithelium. It is doubted that the reactions 

 in the sow's uterine epithelium are indica- 

 tive of steroidal synthesis, inasmuch as 

 Wislocki and Dempsey (1945) encountered 

 no birefringence in the epithelium. Estro- 

 gens have been detected by various means 



