902 



SPERM, OVA, AND PREGNANCY 



pathologic conditions as "mucoid degenera- 

 tion." This placental change occurs in villi 

 as early as the sixth week of gestation and 

 is especially evident in the regressing villi 

 of the chorion laeve. 



Ashbel and Hertig (1952), using the car- 

 bonyl reaction of Ashbel and Seligman, 

 have reported that ''otherwise normal-ap- 

 pearing placentas from 6 cases of toxemia 

 of pregnancy with gestational ages of 34 

 to 39 weeks contained increased amounts of 

 ketosteroid, indicating a distinct metabolic 

 abnormality." On the basis of the belief 

 that there is an increased degeneration of 

 the syncytium in pre-eclampsia, Smith and 

 Smith (1948) postulated a marked decline 

 in the production and secretion of ketos- 

 teroids by this tissue. The findings of Ash- 

 bel and Hertig would not seem to be in har- 

 mony with the supposition of the Smiths. 

 However, one might interpret the increase 

 in carbonyl compounds observed by them 

 as possibly representing increased storage 

 associated with diminished secretion of 

 ketosteroids. The observations of Deane, 

 Shaw and Greep (1948) on the cells of the 

 adrenal cortex provided the basis for this 

 speculation ; they found that on stimulation 

 of the adrenal cortex the lipid droi)lets of 

 the cortical cells diminished in size, whereas 

 on gradual reduction of normal stimulation 

 the droplets first enlarged but subsequently 

 diminished with extreme shrinkage of the 

 cells. The extent and direction of the 

 changes depended on the degree and dura- 

 tion of stimulation or its cessation. It should 

 be recalled in this connection that Bienen- 

 feld (19121 reported an unusually high con- 

 tent of lipid in the placenta in eclampsia. 



The main difficulty in relating eclampsia 

 and the toxemias of pregnancy to prema- 

 ture and excessive age changes in the pla- 

 centa is that the alterations differ from 

 those characterizing normal placental aging 

 in degree only, there being no really dis- 

 tinctive qualitative or absolute quantita- 

 tive histopathologic changes that can be 

 readily ascertained. Inasmuch as the topog- 

 raphy of the placental villi and cotyledons 

 is complex and variable, and many of the 

 age changes are spottily disseminated, the 

 human placenta presents grave obstacles 

 to adequate histologic sampling for the 



purpose of establishing relative degrees of 

 age changes, whether they be normal or 

 pathologic. Methods depending on the use 

 of frozen sections combined with drastic 

 histochemical procedures are especially un- 

 suitable. The suggestion is offered that 

 the placenta should be investigated for 

 possilDle structural and functional differ- 

 ences with relationship to the various seg- 

 ments or divisions of the villous tree. The 

 possibility that there are differences which 

 characterize various portions of the villi is 

 suggested by several of the histochemical 

 findings reported in the previous pages. 

 There is also the possibility that the struc- 

 ture and function of different segments of 

 the villi, in a regional pattern from the 

 basal plate to the surface of the placenta, 

 may be related to the direction and man- 

 ner of flow of the maternal blood in the in- 

 tervillous space. With respect to this, al- 

 though investigations of the uteroplacental 

 circulation in man (Spanner, 1935b) and 

 rhesus monkey (Ramsey, 1949, 1954) have 

 slied much light on the uterine decidual 

 vessels, practically nothing is known about 

 the character and flow of the maternal 

 blood in the intervillous space in relation 

 to the villous trees. Moreover, because de- 

 finitive information on the topography of 

 the placental villi is lacking, previous de- 

 scriptions of the pattern of the fetal villous 

 circulation have not seemed particularly 

 helpful (Spanner, 1935b; Boe, 1953). When 

 the pattern of the fetal villi is worked out 

 and correlated with the pathways of both 

 the fetal and maternal blood streams, dif- 

 fering functional segments of the villi may 

 become apparent, thus permitting deeper 

 insight into questions of placental exchange 

 of metabolites and aging of the placenta, 

 both normally and in the toxemias. 



C. PERIPHERAL CYTOTROPHOBLAST 



The peripheral cytotrophoblast of the 

 first trimester of gestation comprises the 

 trophoblastic cell columns, cell islands, and 

 the trophoblastic shell (Figs. 15.2 and 

 15.3). A detailed account of the differentia- 

 tion and growth of these structures in the 

 rhesus monkey was given by Wislocki and 

 Streeter (1938). Eventually the tropho- 



