Distribution and Heterogeneity of Mast Cells in Female Reproductive Tract and Ovary on Different Days of the Oestrus Cycle in Angora Goats T Karaca 1 , S Arikan 2 , H Kalender 3 and M Yoruk 1 1 Department of Histology and Embryology, Faculty of Veterinary Medicine, University of Yuzuncu Yil, Kampu ¨s; 2 Department of Physiology, Faculty of Veterinary Medicine; 3 Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, University of Kirikkale, Kirikkale, Turkey Contents The physiological distribution of mast cells (MCs) in the reproductive tract and ovary of 12 Angora goats was deter- mined using light microscopic histochemical techniques. Uterus (corpus uteri and cornu uteri), uterine cervix, uterine tubes (isthmus and ampulla) and ovary samples were obtained by laparatomy from groups of animals during metoestrus, dioestrus and proestrus (days 5, 10 and 16 of the oestrous cycle). Tissues were fixed in Mota’s fixative (basic lead acetate) for 48 h and embedded in paraffin. Six-micrometre-thick sections were stained with toluidine blue in 1% aqueous solution at pH 1.0 for 5 min and alcian blue-Safranin at pH 1.0 for 30 min. MCs were generally associated with blood vessels in all reproductive organs. In the uterus, they were concentra- ted mainly in the close of the uterine gland and deep stroma in the endometrium. Higher MC numbers were observed by toluidine blue staining in the uterus, uterine cervix and uterine tubes on days 10 (corpus uterine: 4.7 ± 3.8 and cornu uterine: 4.9 ± 3.5) and 16 (corpus uterine: 5.9 ± 4.5 and cornu uterine: 5.4 ± 2.4) of the oestrous cycle compared with day 5 (p < 0.05). Mast cells were not observed in the follicles, the corpus luteum and the underside of the surface epithelium of the ovarian cortex, but were observed in the interstitial cortical stroma and the ovarian medulla. In the ovary, MC numbers were significantly higher on day 16 of the oestrous cycle (cortex: 3.4 ± 2.4 and medulla: 5.7 ± 4.5, p < 0.05). Safra- nin-positive connective tissue MCs were not observed in the uterine tube on any occasion. These results indicate oestrous cycle-related changes in the number and location of MCs in goat reproductive organs. Introduction Mast cells (MCs) are derived from haematopoietic precursors and represent critical effector cells in allergic diseases and other IgE-dependent responses (Galli 1993; Skaper et al. 2001). In addition to being effector cells in immediate hypersensitivity reactions, MCs appear to be involved in other pathophysiological processes including delayed-type hypersensitivity, wound healing, fibrosis and neuroimmunological disorders such as multiple sclerosis (Galli 1993; Purcell and Atterwill 1995). Mast cells appear to have different morphological, biochemical and functional characteristics in different parts of the body (Rogers 1996; Noviana et al. 2001). Their activities are regulated by a number of factors, including cytokines, which influence the maturation, differentiation and proliferation of MCs (Galli 1993). Mast cells can be differentiated into two types: mucosal mast cells (MMC) and connective tissue mast cells (CTMC). The two types have been relatively easy to distinguish in rodents, because they stain differently, differ in size and are found in different tissues (Denberg 1988). Mast cells may have differing granular contents, which result in heterogeneous histochemical character- istics when stained with alcian blue/Safranin. The combination of these two dyes can distinguish mucosal (blue-staining) mast cells, containing low-sulphated glycosaminoglycans, from serosal (red-staining) mast cells, containing high-sulphated glycosaminoglycans (Zhuang et al. 1999). Mucosal mast cells differ from those in connective tissue according to morphology at light and the electron microscopic level, histochemical characteristics, muco- polysaccharide content, content of IgE and responsive- ness to mast cell degranulating agent (Bienenstock and Befus 1980). The number of mast cells in female reproductive organs (uterus, uterine tube and ovary) has been found to vary during the oestrous cycle in rats (Karaca et al. 2007), mice (Padilla et al. 1990; Batth and Parshad 2000), voles (Microtus agrestis) (Brandon and Evans 1983), guinea pigs (Harvey 1964) and cows (Likar and Likar 1964; Ozen et al. 2002). Mast cells have been identified in the endometrium in small numbers, pre- dominantly in the stromal tissue (Crow et al. 1991; Drudy et al. 1991). However, the greatest number of MCs is located in the myometrium (Rudolph et al. 1993). Studies carried out so far reveal light microscopic changes in the properties and distribution of MCs in the ovary and uterus. In species with a well-developed interstitial cortical stroma and a long oestrous cycle, such as cows, MCs reside in the cortex and in the medulla (Nakamura et al. 1987). In species with a short oestrous cycle, such as rats and hamsters, MCs are found only in the medulla (Jones et al. 1980; Krishna et al. 1989). Du Bois et al. (1980) demonstrated significantly higher MC counts in the isthmus than in the ampulla for all stages of the bovine oestrous cycle and found that the MC counts in the isthmus were higher during metoestrus, dioestrus and proestrus. In the ampulla, MC numbers were significantly higher during metoestrus and dioestrus than during oestrus. Likar and Likar (1964) reported that in the bovine uterus, the MC count was higher in the oestrual phase than in the luteal phase. In rats, relatively low counts of MCs occur in the ovary of pregnant females (Parshad and Kathpalia 1990). Very little is known about the importance of ovarian MCs during pregnancy, although a role in the uterus with regard to the embryo implantation has been proposed in some species (Hore and Mehrotra 1989; Padilla et al. 1990), with higher release of histamine by Reprod Dom Anim 43, 451–456 (2008); doi: 10.1111/j.1439-0531.2007.00934.x ISSN 0936-6768 Ó 2008 The Authors. Journal compilation Ó 2008 Blackwell Verlag