Characterization of Foamy Epithelial Surface Cells in the Canine Endometrium

Abstract

In mature bitches, endometrial epithelial surface cells modify function and corresponding morphology during the oestrous cycle. During late metoestrous, endometrial epithelial surface cells frequently accumulate fat and thereby adopt a foamy morphology. This cyclic appearance of foamy endometrial epithelial cells (fEECs) seems to be physiological in the dog, whereas in other species, it indicates pathological changes. Function of these fEECs has not been identified until now. Therefore, the aim of the study was to characterize the fEECs by means of transmission electron microscopy and immunohistochemistry. Different manifestations of fEECs were observed and analysed with regard to proliferative activity and presence of different epithelial adhesion molecules including PLEKHA7, β-catenin and E-cadherin. PLEKHA7 was restricted to the apical regions of the fEECs, whereas E-cadherin and β-catenin were demonstrated basolateral. The immunohistochemical detection of steroid hormone receptors demonstrated the responsiveness of the fEECs to steroid hormones. Intense progesterone receptor expression was observed in the fEECs indicating a high responsiveness to this hormone. Considering a potential function of the fEECs, we hypothesized that leptin, a hormone produced by other lipid-accumulating cells and described to be involved in reproduction, in particular during implantation, might also originate from the fEECs which was confirmed by immunohistochemical methods. Moreover, leptin receptor was found in fEECs indicating the fEECs as both, source and target for leptin. Therefore, we conclude that fEECs in the canine uterus have a potential role in early pregnancy events and that the different observed manifestations might simply reflect the variations of signs of pseudopregnancy among bitches.

Morphological Characteristics and Expression of Estrogen and Progesterone Receptors in the Canine Endometrium During the Estrus Cycle, Cystic Endometrial Hyperplasia and Pyometra

“…The anestrus phase of the estrus cycle was characterized by hardly notable crypts of the epithelium. All described changes were described by other authors [2][3][4]16,17]. Also, beside the histological changes on the endometrium, different phases of the estrus cycle were also characterized by cyclic changes of estrogen and progesterone receptor concentrations on the uterine cells which was confi rmed by using an immunohistochemical technique.…”

Leptin in the canine uterus and placenta: possible implications in pregnancy

“…Protein signals for LepR and Lep in the uteri of women were predominantly localized in the luminal epithelium, in the endometrial glands and in stromal cells [ 3 ], which is in accordance with our study. Bartel et al [ 50 ] also described immunoreactivity for both proteins in the surface and glandular epithelium, and occasional Lep staining in the stromal parts of the endometrium during diestrus and anestrus in non-pregnant dogs, but the date of ovulation was not known. In contrast to our study, Schäfer-Somi et al [ 37 ] and Beceriklisoy et al [ 39 ] did not detect Lep mRNA expression by qualitative PCR in the uterus of non-pregnant bitches in early diestrus or in pregnant dogs at pre-implantation and at d 20–35 of gestation.…”

“…To date, Lep expression in the canine uterus was only examined in the first half of gestation using qualitative PCR, which yielded negative results [ 37 , 39 ]. Bartel et al [ 50 ] found Lep and LepR immunoreactivity in the uteri of non-pregnant bitches, but pregnant dogs were not studied.…”

The morphological changes in bitches endometrium affected by Cystic Endometrail Hyperplasia - Pyometra complex – the value of routine histopathological examination

“…During the estrous cycle, the endometrium of the bitch undergoes distinct morphological and biochemical changes [9,[12][13][14][15]. The important role in regulating these changes is mainly attributed to steroidal hormones [10,15].…”