Evaluation of mast cells in calf and heifer uteri

Little is known about the characteristics of mast cells present in the wall of the bovine uterus. The aims of the present study were to determine the main distribution patterns of mast cells residing in the uterine walls of calves and heifers and to obtain reference values for these cells in order to assist in the evaluation of endometrial biopsies in cows. A total of 59 young Italian Friesian cattle (30 prepubertal heifers 8 to 10 mo old and 29 post pubertal heifers 15 to 18 mo old that had not calved) were chosen on the basis of absence of lesions of the genital tract, following clinical examination for macroscopic and microscopic pathology. Only pubescent heifers which were in the diestral phase of their cycle were chosen. After slaughter, tissue samples were collected from the uterine body and each horn, and were then fixed in buffered formalin. Histological sections (5 micrometers), stained with Toluidine blue (0.003% at pH 4.9), were used for cell counts in 5 optical fields at x 400 magnification (0.18 mm(2)), randomized for each layer from both the wall of the body and each horn: stratum compactum (SC), st. spongiosum (SS), st. musculare (SM), st. vasculare (SV) and tunica serosa (TS). The number of mast cells in the layers for pre- and post-pubertal heifers were, respectively: SC 5.5 and 11.2; SS 2.8 and 2.7; SM 0.8 and 2.8; SV 3.0 and 4.6; and TS 1.4 and 3.9. The results indicated that the number of mast cells increased with age (calves 2.7 vs heifers 4.7; P<0.001), particularly in heifers, that the values for the uterine body and horns were not different (4.5 and 4.8) and that SC and SV had the highest values in both groups. The reference values proposed for the resident mast cells are (mast cells/ x 400): 11 for SC alone, 7 as an average of SC+SS, and 5 as an average of SC+SS+SM+SV.