Morphological Changes and Infiltration of Immune Cells in the Endometrium of Anoestrus Gilt in Relation to the Ovarian Appearance and Serum Progesterone

Abstract

The present study investigates morphological changes and distribution of the leukocyte subpopulation in the endometrium of anoestrus gilts in relation to reproductive cycles and serum progesterone (P4). Selected genital organs from 30 gilts culled due to anoestrus were examined. The genital organs were classified according to the ovarian appearance into 3 groups, i.e. inactive (n = 10); follicular (n = 10); and luteal phase (n = 10). Blood samples were collected prior to slaughter to determine serum P4. Seven tissue samples were randomly collected from the uteri of the gilts and were examined for histological structures, i.e. epithelial types and height, number of blood vessel, secretory vesicle and endometrial glands. Number of leukocyte subsets, i.e. lymphocytes, neutrophils, eosinophils, macrophages and plasma cells were counted. On average, age and body weight at culling of the gilts were 306.4±39.9 d (range 233-407 d) and 150.4±24.8 kg (range 104.0-205.5 kg). Lymphocyte was the most common immune cell in all tissue layers and in all stages of the reproductive cycle. Lymphocytes in glandular layer in the inactive phase was higher than in the follicular (p=0.02) and luteal phases (p=0.05). Neutrophils in both epithelial and subepithelial layers in follicular phases was higher than luteal and inactive phases (p<0.001). Eosinophil in subepithelium in the luteal phase was higher than inactive (p=0.004) and follicular phases (p<0.001). An increase in the serum P4 resulted in an
increase number of uterine glands (p<0.001), a decrease number of lymphocytes in all tissue layers (p<0.05), a decrease number of neutrophils in subepithelial layers (p=0.03) and an increase in the number of eosinophils in subepithelial layers (p<0.001). In conclusion, the infiltration of the leukocyte subpopulation in the endometrium of
anoestrus gilts is largely dependent on the ovarian function. Neutrophils and eosinophils were common immune cells in follicular and luteal phases, respectively.