FCETAL NUTRITION: THE PLACENTA 



499 



the connective tissue cells undergo active 

 division, and they enlarge to form the 

 decidual cells (Fig. 153). Before the exca- 

 vation of the "Eikammer" they are prob- 

 ably not found, though Peters described 

 the commencement of a decidual change 

 before that stage. In Merttens' 1 ovum 

 large decidual cells were found, many of 

 them fusiform and lying parallel to the 

 surface. The decidual change arises first in 

 the connective tissue cells near the ovum, 

 and later it extends more deeply in the 

 compacta. There is no special perivascular 

 development as in the rabbit, and no endo- 

 thelial proliferation as in the hedgehog and 

 bat, though the latter may occasionally occur 

 in tubal pregnancy (Webster 2 ). 



The capillaries dilate to sinuses, and new 

 vessels are also formed in the compacta. 

 Many of them are opened by the trophoblast 

 and perhaps by the mononuclear cells, and 

 gradually more and more blood is effused 

 into the trophoblastic lacuna?. In them it 

 does not clot, the syncytium acting as an 

 endothelium, but at a certain stage the 

 blood begins to circulate and continues to 

 do so throughout pregnancy. The gland- 

 ducts are destroyed in the necrotic zone. 

 In the underlying compact zone they are 

 found dilated in the serotiiia and base of the 

 reflex'a, but even in Bryce and Teacher's 

 ovum the epithelium showed signs of de- 

 generation and desquamation. 



With the formation of the space between 

 the ovum and the decidua, a permanent 

 attachment of the two structures is brought 

 about. The development- of the villi has 



1 Merttens, " Beitrage zur normalen und patho- 

 logischen Anatomic der menschlichen Placenta," 

 Zeitsch. f. freburtsh. u. Gyniik., vols. xxx. and xxxi., 

 1894-95'. 



2 Webster, Human Placentaticm, Chicago, 1901. 

 Wade and Watson (Jour, of Obstet. and Gynec. of 

 Brit. Emp., 1908) also state that in tubal pregnancy 

 some of the decidual cells are formed from endo- 

 thelium. 



FIG. 153. Condition of 

 the glands at the be- 

 ginning of pregnancy 

 in man (after Kundrat 

 and Engelmann). 

 (From Quairis An- 

 atomy, Longmans.) 



<, Compact layer near 

 free surface of de- 

 cidua : the glands are 

 here somewhat en- 

 larged, but not very 

 tortuous, and the 

 mucous membrane is 

 rendered compact by 

 the hypertrophy of 

 the interglandular 

 tissue ; sp., spongy 

 layer containing the 

 middle portion of the 

 glands greatly en- 

 larged and tortuous, 

 producing a spongy 

 condition in the 

 mucous membrane ; 

 d, deepest portion of 

 glands, elongated and 

 tortuous, but not 

 much enlarged ; m, 

 muscularis. 



