Find information on animal health topics, written for the veterinary professional.

Twin fetal membranes, equine

Courtesy of Dr. Patricia Sertich.

A large, tan, avillous area is present between the larger chorioallantois on the left and the smaller chorioallantois on the right. Microvilli form only where the chorion is able to contact the endometrium, hence, the large avillous area between the adjacent twin chorions.