254 



EMBRYOLOGY. 



Jf 



middle of their course the 

 glands are highly tortuous 

 and have enlarged and be- 

 come pocketed. 



The dilate cylindrical epi- 

 thelium at the surface of the 

 mucous membrane of the 

 uterus gradually disappears 

 entirely ; it is destroyed as 

 early as the end of the first 

 month of pregnancy (MINOT). 

 In the glands it undergoes 

 fundamental changes. In 

 the first months all the cavi- 

 ties are still lined with it, a 

 condition which, on account 

 of the increase in the size of 

 the cavities, presupposes an 

 active cell-growth. Mean- 

 while the originally elongate 

 cylindrical cells are in part 

 converted into small cubical, 

 in part into small flat struc- 

 tures, except in the portions 

 of the glands which adjoin 

 the muscular membrane. 

 The cells here preserve more 

 or less their normal form up 

 to the end of pregnancy, and 

 subsequently serve for the 

 regeneration of tlie epithelial 

 lining of the mucous mem- 

 brane of the uterus. 



In the fourth and fifth 



Fig. 146. Cross section through the 

 mucous membrane of a uterus at the 

 beginning of pregnancy, after KUND- 

 RAT UNO EXUELMAXX. 



C, Compact layer ; Sp, spongy layer ; 

 M, musciilature of the uterus : tr, 

 funnel-shaped mouths of the uterine 

 Clam's; e, enlarged region; dh, am- 

 pullae produced by the wine ings and 

 evagiitations of the Avowing- glands. 



