Changes in the mast cell distribution in the canine ovary and uterus throughout the oestrous cycle

This is the first study describing the relation between the phase of the oestrous cycle and the number of mast cells (MCs) in the canine ovaries and uterine horns. The total number of MCs was counted in cortex ovarii, medulla ovarii, endometrium and myometrium. The number of MCs was compared in all of these areas among the bitches in the early follicular phase, luteal phase and anoestrus. MCs were the most numerous in the early follicular phase and in the luteal phase; however, they were significantly less numerous during anoestrus. Based on the results, it was concluded that the number of MCs in ovaries and uterine horns fluctuates during the oestrous cycle. The results of this study may contribute to clarifying the role of MCs in the reproductive organs of bitches.     

The influence of the oestrous cycle on the intravenous glucose tolerance test in the bitch

The possibility that endogenous oestrogen and progesterone affect carbohydrate tolerance in the female dog was investigated by relating the results of repeated intravenous glucose tolerance tests to the phases of the oestrous cycle, namely anoestrus, pro-oestrus, oestrus and dioestrus. Neither the glucose tolerances nor the insulin responses were significantly different between these phases of the oestrous cycle in 12 Dalmatian bitches.     

N-acetyl- beta -D-glucosaminidase activity in the endometrial epithelium of the cow's uterus during the oestrous cycle and pregnancy

The levels of N-acetyl-beta-D-glucosaminidase (NAGase) were measured in the endometrial epithelial tissue of the bovine uterus during the oestrous cycle and during pregnancy. NAGase levels were significantly (P<0.001) higher in the epithelial tissue of the cow's uterus during the luteal phase of the cycle and during pregnancy than during the non-luteal phase. There were significantly (P<0.001) higher mean NAGase values in the epithelial than the subepithelial layers of the uterus in the two cycle phases and in pregnancy. Leucocyte numbers were significantly (P<0.05 and P<0.001) higher in the cows' uteri during the non-luteal phase than during the luteal phase and pregnancy, respectively. It is concluded that the endometrial epithelial layer is significantly active in terms of NAGase release and that this may be related to increased progesterone concentrations. In addition, the epithelial tissue (not leucocytes) appears to be the main contributor to the total NAGase activity in uterine tissue.     

Expression of oestrogen receptor,androgen receptor and progesterone nuclear receptor in sheep uterus during the oestrous cycle

Oestrogen, androgen and progesterone are involved in the regulation of uterine physiological functions, with the participation of the following proteins: oestrogen receptor (ER), androgen receptor (AR) and progesterone nuclear receptor (PGR). In this study, we used immunohistochemistry to detect the localization of ERα, ERβ, AR and PGR in sheep uterus. Additionally, we used real‐time polymerase chain reaction (RT‐qPCR) and Western blot technique to analyse their expression profiles at different stages of sheep oestrous cycle in the endometrium and myometrium. Immunohistochemical analysis showed that ERα, ERβ, AR and PGR were present in sheep uterus in oestrus, mainly in the uterine luminal epithelium, stroma, gland and myometrium. Real‐time polymerase chain reaction results showed that in the endometrium, ERα expression level was highest in oestrus. ERβ and PGR, instead, were highly expressed in pro‐oestrus. In the myometrium, ERα was highly expressed in both oestrus and pro‐oestrus, and ERβ was highly expressed in oestrus and dioestrus. Progesterone nuclear receptor expression was highest in oestrus, followed by metoestrus. In the endometrium, both receptors ERα and ERβ were abundant in pro‐oestrus, while the maximum AR protein content was found in oestrus. At this stage of the oestrous cycle, PGR protein concentration in the myometrium was significantly lower than those observed in other stages. These results suggest that these receptors are important for sheep reproductive function, as their expression at mRNA and protein levels exhibits particular time‐ and tissue‐specific profiles along the oestrous cycle.     

Changes in oestrogen,progesterone and epidermal growth factor receptor concentrations and affinities during the oestrous cycle in the normal mammary gland and uterus of dogs

Changes in the concentrations and affinities of receptors for oestrogen (ER), progesterone (PR) and epidermal growth factor (EGF-R) were studied in mammary glands of healthy bitches with regard to age, the location in the mammary chain and the stage of the oestrous cycle. Uterus was used as the reference tissue for the evaluation of steroid receptors. Mammary and uterine samples from 7 healthy bitches were taken at five stages of the oestrous cycle in such a way that all the locations in the mammary chain were represented at each stage of the cycle (10 samples/dog). ER, PR and EGF-R were detected by biochemical assays using increasing concentrations of tritiated (steroids) or iodinated (EGF) ligands. A significant direct correlation was found between the ER and PR concentrations for mammary and uterine samples. No significant correlation was found between the steroid receptors and EGF-R concentrations. Mammary ER concentrations were significantly higher in bitches of 5 years of age or older than in younger ones; in posterior glands (4th and 5th pairs) than in anterior glands; and in the mid-luteal phase. Mammary PR did not vary significantly with age or location but was significantly lower in the early luteal phase than in other phases. A similar decrease in PR concentrations was observed in the uterus during the early luteal phase and uterine ER and PR concentrations were very low in the mid-luteal phase. Mammary EGF-R were not significantly higher in the early or mid-luteal phase than in pro-oestrus or anoestrus.The differences observed between the uterine and mammary steroid receptor concentrations during the oestrous cycle could be due to different mechanisms for regulating steroid receptor expression in the two tissues. Mammary EGF-R concentrations may be linked, as in other species, to cellular proliferation and/or to the serum progesterone concentrations.Abbreviations BSA bovine serum albumin - EGF epidermal growth factor - EGF-R receptor for epidermal growth factor - ER oestrogen receptor - K _d dissociation constant - LH luteinizing hormone - p probability of error - PR progesterone receptor     

Immunohistochemical evaluation of the equine endometrium during the oestrous cycle

Endometrial biopsies were obtained from four mares during consecutive oestrous cycles on the first day of oestrus, on the day when ovulation was detected, and four and eight days after ovulation. Cycle stages were confirmed by means of rectal palpation, ultrasonography and plasma progesterone determination. Immunohistochemical evaluation of the formalin fixed biopsy specimens was performed using a peroxidase anti-peroxidase technique. Immunoglobulin (Ig)A-, IgM-, IgG(Fc)- and IgG(T)-containing cells were detected in all biopsies; with IgA- and IgG(Fc)-containing cells generally predominating. There was no cyclical trend of Ig-containing cell numbers for any isotype. Free immunoglobulins of the four classes evaluated were frequently seen in luminal epithelium, glandular epithelium and secretions, and interstitium. This study of endometrial biopsies from a limited number of cycling mares suggests the presence in the equine endometrium of free and intracellular immunoglobulins of the classes A, M, G(Fc) and G(T) without any apparent cyclical trend.     

Apoptotic cell death in the porcine endometrium during the oestrous cycle

It has been reported that apoptosis plays an essential role in controlling the physiological cell kinetics in the human and rodent endometrium but this type of death has never been studied in the porcine endometrium. The aim of this study was to investigate the apoptotic cell death in the porcine endometrium during the middle (Days 9-11) and late (Day 13) luteal phase, during the luteolysis (Day 15) and early follicular phase (Days 17-19) of the oestrous cycle. Apoptotic cells were identified by in situ DNA 3'-end labelling method. It was revealed that the greatest number of apoptotic cells in the luminal and glandular epithelium was found on Days 17-19 and on Day 15 of the oestrous cycle, respectively. In the stroma, the greatest number of these cells was found on Days 9-11. Our data have shown that in the porcine endometrium, both epithelial and stromal cells undergo apoptosis and that the number of apoptotic cells varies depending on the phase of the oestrous cycle.     

Expression of Frizzled 2 in the mouse ovary during oestrous cycle

The Wnt/β‐catenin pathway is a conserved signalling pathway that regulates gene expression and controls diverse developmental processes such as cell fate specification, cell proliferation and cell differentiation. To our knowledge, the potential role of this pathway in the adult ovary has been poorly addressed. To this end, we investigated the expression pattern of Frizzled 2 in the mouse ovary during oestrous cycle by real‐time Q‐PCR, in situ hybridization, Western blotting and immunohistochemistry. In this study, we used uterine wet weight and H3.2 mRNA level as two markers for classification of mouse oestrous cycle. We found that both uterine wet weight and H3.2 mRNA are the highest in the proestrus and decrease from oestrus to diestrus. During oestrous cycle, Frizzled 2 mRNA and protein exhibited the highest level in the proestrus stage and rapidly reduced from oestrus to diestrus. In situ hybridization results showed that the positive signals for Frizzled 2 are highly detected in the oocyte and stroma in proestrus stage, while moderate or weak Frizzled 2 mRNAs are localized in the oocyte, granulosa cells, stroma and corpus luteum from oestrus to diestrus. The localization pattern of Frizzled 2 protein is mostly consistent with its mRNA, but stronger Frizzled 2 proteins are present in the granulosa cells and membrane of oocyte in oestrous cycle. Our data suggest that Frizzled 2 may be involved in regulating follicle growth, oocyte maturation and luteinization during oestrous cycle.     

Changes of receptor mRNAs for oxytocin and estrogen during the estrous cycle in rat uterus

Oxytocin receptor (OTR) mRNA levels increase dramatically near term and is potently stimulated by estrogen because increased OTR mRNA levels result from estrogen treatment in ovariectomized rat uterus. In this study, OTR, estrogen receptor (ER) alpha and ERbeta mRNA levels in the rat uterus during the estrous cycle were examined by quantitative RT-PCR. OTR mRNA levels during the estrous cycle began to increase on diestrus (P<0.05, vs value on estrus), reached maximal increase both in the morning (1000-1130 hr) and afternoon (1600-1630 hr) on proestrus (P<0.01, vs metestrus, diestrus and estrus) and then declined on estrus. In contrast ER alpha mRNA levels began to decrease on diestrus, reached statistical significance both in the morning and the afternoon on proestrus (P<0.01, vs metestrus, diestrus and estrus) and returned to the value of metestrus on estrus. ERbeta mRNA levels were low in the morning and the afternoon on proestrus (P<0.01, vs metestrus and estrus) and also returned to metestrus values on estrus. Treatments with estrogen for 3 days significantly decreased both ERalpha and ERbeta mRNA levels. It can be concluded from these results that during the estrous cycle, OTR mRNA levels in rat uterus predominantly increase at proestrus with a decrease in ERalpha and ERbeta mRNA levels, which is probably due to the increased estrogen levels in circulation before ovulation.     

Tissue concentrations of eosinophilia in the bovine oviduct and uterus of different stages of the oestrous cycle

Numbers of eosinophils in the bovine oviduct and uterus were determined during the oestrous cycle. The eosinophil numbers in the oviduct (ampulla and isthmus) and horn of the uterus during oestrus were significantly higher than during dioestrus. The number of eosinophils in the uterine cervix was lower than in the uterine horn for all stages of the oestrous cycle. In the oviduct, eosinophils accumulated in the lamina propria of the tunica mucosa, in the tunica muscularis and in the connective tissue of the tunica serosa. In the uterus, they were concentrated mainly in the upper parts of the stroma in the endometrium. Degranulation of eosinophils was observed during oestrus when they increased in number in the oviduct and uterus.     

Endocrinology of the oestros cycle in the bitch

This presentation aims to review what is currently known of several aspects of the endocrinology of reproduction in the dog. Each phase of the oestrous cycle is described with respect to the changes occurring in clinical appearance, vaginal cytology, behaviour and the levels of pituitary and ovarian hormones; comment is also made about the factors influencing the length of the oestrous interval. The variable nature of the reproductive cycle in the bitch is emphasized as is the care necessary, on the part of the practising veterinary surgeon, in interpreting the significance of the changes that occur. Résumé. Dans cet article, les auteurs passent en revue les connaissances actuelles sur divers aspects de I'endocrinologie de la reproduction chez le chien. 11s décrivent chaque phase du cycle de l'oestre en considérant les changements de l'aspect clinique, de la cytologie vaginale, du comportement et du taw des hormones pituitaires et ovariennes; ils parlent également des facteurs qui influencent la durée de l'intervalle entre les oestres. 11s soulignent la nature variable du cycle reproducteur de la chienne, ainsi que le soin avec lequel le chirurgien vétérinaire doit interpreter I'importance des changements qui se produisent. Zusammenfassung. Diese Arbeit beabsichtigt darzustellen, was gegenwärtig über verschiedene Aspekte der Endokrinologie der Fortpflanzung des Hundes bekannt ist. Jede Phase des Östruszyklus wird hinsichtlich der Veränderungen des klinischen Bildes, der Vaginalcytologie, des Verhaltens und der Konzentrationen der Hypophysen- und Ovarialhormone beschrieben; ausserdem werden die Faktoren behandelt, welche die Länge des Östrusintervalls beeinflussen. Die veränderliche Natur des Fortpflanzungszyklus der Hündin wird betont, ebenso wie die Sorgfalt, die seitens des praktischen Tierarztes bei der Beurteilung der Signifikanz der auftretenden Veränderungen erforderlich ist.     

Uterine motility of the sow during the oestrous cycle and early pregnancy

With electromyography and strain gauges the uterine motility of the sow during the oestrous cycle and early pregnancy was studied. Special attention was paid to characterization of myometrial activity at the time of intrauterine migration of blastocysts.From recordings of 4 animals (3 became pregnant) 3 types of electrical spiking activity (each could be correlated with an elevation of the strain gauge tension) were discerned. Two of them appeared regularly and were suitable for analysis: High Voltage Slow Acticity (with relative high amplitude and low frequency of spikes) and Low Voltage Fast Activity (with relative low aplitude and high frequency of spikes).The sexual status markedly influenced myometrial activity: during prooestrus and oestrus only one type of electrical activity was present whereas the myoelectrical complex (an episode of this activity and the subsequent interval of inactivity) was shorter than 10 min. During dioestrus the myoelectrical complex was longer than 10 min and High Voltage Slow Activity (solely on the cervix and bifurcation) and Low Voltage Fast Activity occurred simultaneously in episodes which mainly appeared to originate on the bifurcation.The characteristics of uterine activity during pregnancy were similar to those of a cyclic sow until day 12. It was only on day 12 that gestation appeared from an increased frequency of myoelectrical complexes.It is concluded that Low Voltage Fast Activity as it was found on the uterine horn at days 8–9 might be involved in the process of intra-uterine migration of blastocysts. In cyclic and in pregnant animals the patterns of Low Voltage Fast Activity were similar. Therefore, the occurrence of Low Voltage Fast Activity is independent of the actual presence of blastocysts. It seems to be exhibited in dependence on the ovarian hormones.