22S 



yORMA L HISTOL OGY. 



also believe that the villous syncytium is not derived from the 

 chorionic ectoderm, but from the uterine epithelium. In sections 

 of these tissues, while the placenta is developing, it is extremely 

 difficult, often impossible, to decide whether given cells are of foetal 

 or maternal origin (Fig. 20G). After the birth of the child and the 

 expulsion of the membranes the uterine mucous membrane is regen- 

 erated from the tissues remaining in the superficial layers of the 



muscularis mucosae. 



Fig. 205. 



fs »s — - 



. -' . .* 



1 



.' '. % '^PM^^ Decidual 



■J y cells 



51 : 



o ,- '.;?" • ■' -' * Z' n . - £ iSP"^ 

 Syncytium---** *« a * * ',»!»■>• »■ .. ■=»- _"-;...- 







Canalized 



fibrin 



r ■.«■ „ 



c » » 



*g$V fc ,1 NyM" 



tTmV. • ■* * jT-v ■■■-■ •' *••»<. o 

 a* - ■ .* - it;- 1 _ 



Connective 



tissue 



J?.. I Oblique section 



,?{*• £*- of syncytium 



*** of villus 



I 



From a 



section through a human placenta at the fifth month of pregnancy. (X 80.) 



The mucous membrane of the cervical portion of the uterus does 

 not participate in these changes incident to menstruation and preg- 

 nancy, and the connective tissue underlying its epithelial lining is 

 more fibrous in character than that in the corresponding part of the 

 uterine body. About the middle of the cervical canal the ciliated 

 epithelium, which is continuous with that of the body, passes into 

 a stratified epithelium, which extends over the cervix uteri, the 

 portio vaginalis, and the inner surface of the vagina to join that of 

 the epidermis upon the labia minora. The fibrous tissue beneath 

 this stratified epithelium possesses papilla? similar to those upon the 

 skin, and contains mucigenous glands, which secrete a tenacious 



