Fig. 12.

Reproductive mucosal immune system. (A) Schematic of the mucosal immune system throughout the nongravid female reproductive tract. The vagina and ectocervix are lined with squamous epithelial cells. Columnar mucosa epithelium is present throughout the upper female reproductive tract including the endocervix, uterine endometrium, and fallopian tubes. (B) Schematic of the mucosal immune system of postpartum female bovine reproductive tract. The vulvar opening acts as the portal for entry and clearance of microbial contaminants. Multiple epithelial layers in the vestibule (a) and vagina (b) prevent bacterial entry at these anatomic sites unless they have been breached because of laceration during delivery. The cervix (c), although still dilated after calving, provides another barrier to the entry of microbes into the uterus because of epithelial folding and secretion of mucus that flows outward to the vagina. Around the second week postpartum (e), the simple columnar uterine epithelial barrier is breached at the caruncles because of death of epithelial cells. For the next 3 weeks, the uterus responds to microbial contamination and colonization while re-establishing the integrity of the epithelial barrier (d).

(Adapted from Wira CR, Fahey JV, Rodriguez-Garcia M, et al. Regulation of mucosal immunity in the female reproductive tract: the role of sex hormones in immune protection against sexually transmitted pathogens. Am J Reprod Immunol. 2014;72(2):236-258 and from Dadarwal D, Palmer C, Griebel P. Mucosal immunity of the postpartum bovine genital tract. Theriogenology. 2017;104:62-71; with permission.)