Page 510 - Anatomy and Physiology of Farm Animals, 8th Edition

Pregnancy and Parturition / 495

(A) (C)
VetBooks.ir

(B) (D)

Figure 28-4. Placental types classified by distribution of sites of exchange. (A) Diffuse placenta.
(B) Cotyledonary placenta. (C) Zonary placenta. (D) Discoid placenta. Source: Reece, 1997. Reproduced
with permission of John Wiley & Sons, Inc.

COW EWE MARE

Convex Concave Diffuse

Cotyledonary
Figure 28-5. Placental attachments of cow, ewe, and mare. Villi from chorioallantois (black) invaginates
into crypts in maternal uterine epithelium (stippled) in caruncles in the cow and the ewe and in diffuse
locations in the mare.

The size of caruncles increases as preg- The area between the caruncles is devoid of
nancy progresses, and the caruncles are any attachment between the fetal placenta
larger in the gravid (pregnant) horn than and the maternal uterus. The shape of the
in the nongravid horn. The epithelial sur- caruncles in the ewe is slightly different
face of the caruncle is covered with crypts from those of the cow, having a rather large
into which villi of the fetal placenta project. central depression that is the only portion