Microvascular development and growth of uterine tissue during the estrous cycle in mares

OBJECTIVE: To document uterine growth and microvascular development in the endometrium of uteri with differing degrees of fibrosis as well as uterine growth throughout the estrous cycle of mares. ANIMALS: 30 mares. PROCEDURE: Uterine tissue was obtained during the breeding season from a slaughter facility. Stage of estrous cycle of the mares was assessed on the basis of ovarian structures and plasma progesterone concentrations. Endometrium was characterized by use of light microscopy, and blood vessel walls were marked by histochemical techniques. Microvascular development was evaluated by a computerized image analysis system. Growth of uterine tissue was based on cellular content of DNA and RNA, RNA:DNA, and protein:DNA. RESULTS: Significant differences in vascular density were not observed in the endometrium of uteri obtained from mares euthanatized during the follicular or luteal phase of the estrous cycle, regardless of whether endometrial classification of degree of fibrosis was considered. There was a 3-fold increase in amount of DNA and RNA of endometrial cells in the follicular phase when compared to myometrium. Hypertrophy of endometrial tissue during the luteal phase was reflected by a significant increase in cell protein content and protein:DNA. CONCLUSIONS AND CLINICAL RELEVANCE: Endometrial growth of vascular tissues during the estrous cycle may be coordinated with development of nonvascular tissue. Estrogen and progesterone may play a role in regulation of uterine growth and angiogenesis.     

Effects of endometrial biopsy, uterine culture, and cervical dilatation on the equine estrous cycle

In 10 mares, lysis of the corpus luteum was induced by endometrial biopsy and culture on day 4 after estrus, as evidenced by a sharp decline in serum progesterone concentration and a shortened interestrous interval. Estrus following the manipulations was prolonged. Endometrial biopsy and culture on days 1 and 3 after estrus or manually dilating the cervix on day 4 after estrus also decreased the serum progesterone concentration (within 24--48 hr after manipulation), shortened diestrus, and prolonged the subsequent estrus. In a 2nd experiment, endometrial biopsy on day 4 after estrus shortened the estrous cycle and diestrous period and prolonged the subsequent estrus. It was postulated that these manipulations stimulated corpus luteum regression, followed by estrus and ovulation in the mare.     

Apoptosis in the porcine uterine endometrium during the estrous cycle, early pregnancy and post partum

The mammalian uterus changes dramatically during the estrous cycle, pregnancy, and involution post partum. Dynamic changes in the uterine endometrium are a type of homeostasis and proceed with proliferation and exclusion of cells. Homeostasis of the uterus is closely related to apoptosis involving various hormones and cytokines. The objective of the present study was to determine the morphological features and occurrence of apoptosis in the porcine endometrium during the estrous cycle, early pregnancy, and post partum. Cyclic changes in the morphology of the surface epithelium were observed during the estrous cycle. The heights of surface epithelia were significantly high on day 4 of the estrous cycle and the early pregnancy. The heights of the surface epithelium remained low from days 1 to 31 post partum. We then used terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end-labeling (TUNEL) of the 3'-terminal of fragmented DNA, which is effective for detection of apoptosis in various tissues. We found that apoptosis in the porcine endometrium contributed to homeostasis of the endometrium during the estrous cycle through control of cell proliferation and exclusion. Conversely, apoptosis on days 4 and 8 of gestation before the implantation window depended on the plasma estrogen and progesterone levels; however, suppressive homeostasis of apoptosis occurred at the time of implantation on days 15, 18 and 21 of gestation. Our study is the first to demonstrate apoptotic cell death in the porcine endometrium directly by TUNEL method. The results strongly suggest that uterine homeostasis is mainly controlled by apoptosis during the estrous cycle and early pregnancy.     

Beta-carotene uptake and changes in ovarian steroids and uterine proteins during the estrous cycle in the canine

The uptake of beta-carotene by reproductive tissues and the effects of beta-carotene on reproductive function in the dog are unknown. We studied the uptake of beta-carotene by blood, corpus luteum, and uterine endometrium and the role of dietary beta-carotene in influencing ovarian steroid and uterine protein production during the estrous cycle in the dog. Mature female Beagle dogs (n = 56) were fed diets containing 0, 2, 20, or 50 mg of beta-carotene daily for approximately 6 wk before estrus detection. Blood was sampled at regular intervals from estrus through d 45 after ovulation (d 0 = ovulation), when laparotomy was performed. The ovaries were obtained for the isolation of corpus luteum. The uterus was flushed with phosphate-buffered saline and the endometrium obtained by scraping. Beta-carotene was not detectable in plasma, corpus luteum, or endometrium of unsupplemented dogs. However, beta-carotene and alpha-carotene in plasma, corpus luteum, and uterine endometrium increased in a dose-dependent manner. Alpha-carotene made up a high percentage of total carotenoids even though the alpha-carotene content in the dietary source was very low. Dogs fed 50 mg of beta-carotene had significantly higher concentrations of plasma progesterone between d 12 and 26 compared with unsupplemented dogs. Dietary beta-carotene did not influence plasma estradiol-17beta and total uterine proteins. Therefore, beta-carotene is absorbed into plasma, corpus luteum, and uterine endometrium of dogs. Furthermore, dietary beta-carotene increased plasma progesterone concentrations during the estrous cycle. It is possible that dietary beta-carotene may improve reproductive function in the canine.     

Uptake of beta-carotene by ovarian and uterine tissues and effects on steroidogenesis during the estrous cycle in cats.

OBJECTIVES: To determine uptake of beta-carotene by ovarian and uterine tissues and influence of dietary beta-carotene on steroidogenesis and production of uterine protein during the estrous cycle in cats. ANIMALS: 56 female cats. PROCEDURE: Cats were fed diets containing 0, 0.4, 2, or 10 mg of beta-carotene daily for 8 weeks prior to detection of estrus. At time of observed estrus, all cats were manually induced to ovulate. Blood samples were obtained at estrus and every 2 days until day 14 after ovulation. On that day, cats underment laparotomy, and the ovaries and uterus were removed. Uterine contents were flushed, and luteal and endometrial tissues were obtained. RESULTS: Concentrations of beta-carotene in plasma and luteal and endometrial tissues increased in a dose-dependent manner. Concentrations of plasma progesterone were higher between days 6 and 10 after ovulation in cats fed diets containing beta-carotene and continued to increase through day 14 after ovulation in cats fed a diet containing 10 mg of beta-carotene. Plasma concentration of estradiol-17beta also was higher between days 0 and 4 after ovulation in cats fed diets containing beta-carotene. Cats fed a diet containing 10 mg of beta-carotene had the highest plasma estradiol concentration. Total uterine protein concentration was higher in cats fed beta-carotene, compared with values for cats fed an unsupplemented diet. CONCLUSION AND CLINICAL RELEVANCE: Cats readily absorb beta-carotene. Increased concentrations of progesterone, estradiol, and uterine protein may provide more optimal ovarian function or a better uterine environment for embryonic survival and development.     

Control of the estrous cycle in the mare

All current approaches to manipulating the reproductive biology of the nonpregnant mare are discussed.     

Effects of estrous cycle on the mouse kidney morphology

Although mice kidney morphology shows various sexual dimorphisms, the effect of the estrous cycle has not previously been discussed. In this study, we investigated the effects of the estrous cycle on kidney morphology, including renin-positive areas, of female DBA/2 mice. No effects were confirmed in most of the histometrical parameters, however, the percentage of the renal corpuscles in which cuboidal epithelium covered under 50% of the parietal layer was significantly higher during estrus compared to that during anestrus.     

Canine vaginal cytology during the estrous cycle

Changes which occur in vaginal cytology of the bitch during proestrus, estrus. metestrus and anestrus are correlated. The terms superficial cell index and karyopyknotic index are introduced and explained in order that they may be used to describe vaginal cytological changes and to assist in breeding programs.     

Influence of the estrous cycle on urodynamic and morphometric measurements of the lower portion of the urogenital tract in dogs

OBJECTIVES: To compare the values of the urodynamic parameters of the lower portion of the urinary tract and vaginourethral measurements obtained during the phases of the estrous cycle in dogs and determine possible functional or anatomic modifications of the lower portion of the urinary tract associated with those phases. ANIMALS: 7 adult female Beagles. PROCEDURE: Urethral pressure profilometry, diuresis cystometry, and vaginourethrography were performed in each dog during proestrus; estrus; early, mid, and late diestrus; and early and late anestrus. The maximum urethral pressure (MUP), maximum urethral closure pressure (MUCP), urethral functional and anatomic profile lengths (UFPL and UAPL, respectively), integrated pressure, threshold pressure, threshold volume, compliance, urethral length, and vaginal length and width were measured. RESULTS: For all measurements, significant interindividual variation was detected. Integrated and threshold pressures, APL, and each morphometric value significantly increased from late anestrus to proestrus. Compared with other phases, MUP, MUCP, and integrated pressure values were significantly lower in estrus and early diestrus; UAPL and UFPL values were significantly lower in late diestrus. At each cycle phase in old dogs, MUP, MUCP, threshold pressure, and vaginal length and width were significantly lower (except in proestrus for vaginal measurements) and threshold volume and compliance values were significantly higher, compared with middle-aged dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Urodynamic and morphometric measurements of the lower portion of the urogenital tract are affected by the changes in hormonal balance that occur during the estrous cycle. In sexually intact female dogs, estrous phase determination is important for the interpretation of urodynamic data.     

绵羊发情周期卵巢微血管密度的观察

采用S-P免疫组织化学法通过CD34抗体标记血管内皮细胞,测定绵羊发情周期的0、5、9、12、15d的卵巢内原始卵泡、初级卵泡、次级卵泡、近成熟卵泡、卵巢间质微血管的分布,并分析微血管密度（MVD）的变化规律,探讨绵羊发情周期不同时期各级卵泡微血管生成状态及卵泡微血管生成与卵泡发育的关系。结果表明,绵羊的原始卵泡周围无独立血管网,而初级卵泡的卵泡膜附近开始出现微血管,其MVD值为3.60±0.89,次级卵泡周围微血管密度值显著增高（P〈0.05）,MVD值为6.80±0.84。大窦腔卵泡0、5、9、12、15dMVD分别为15.80±0.84、23.00±2.30、22.40±2.41、21.20±2.28、34.80±2.39。0～5dMVD值显著升高（P〈0.05）,而5、9、12dMVD值差异均不显著（P〉0.05）,12～15dMVD值又明显升高（P〈0.05）。卵巢间质MVD值在各个发情周期各个时期差异均不显著（P〉0.05）。说明绵羊在发情周期内卵泡的血管新生是从初级卵泡开始的,并且卵巢的血管新生主要发生在卵泡上,而卵巢间质无血管新生现象。     

Endocrine mechanisms responsible for different follicular development during the estrous cycle in Hatano high- and low-avoidance rats

Hatano high- and low-avoidance rats (HAA and LAA strains, respectively) were selected and bred according to the avoidance rate in a shuttle-box task. Although they have clear strain differences in ovarian function, their endocrine mechanisms still remain to be clarified. Differences in female reproductive endocrinology between the strains were investigated by means of measuring the plasma concentration of reproductive hormones during the estrous cycle. LAA rats showed approximately threefold lower basal and surge levels of LH, a more than fourfold lower level of FSH surges and higher levels of inhibin A and inhibin B during the estrous cycle compared with the levels seen in HAA rats. The concentration of estradiol-17β in the proestrous stage was significantly lower in LAA rats than in HAA rats. Additionally, LH and FSH secretions from primary cultured anterior pituitary cells with or without in vitro GnRH stimulation were lower in the cells derived from LAA rats and, in terms of FSH secretion, were unresponsive to GnRH in contrast to cells derived from HAA rats. Although an increased number of preantral follicles in diestrus were observed in LAA rats, number of hCG-induced ovulation was lower in LAA rats. LAA rats may have much more follicle growth during the early stage of folliculogenesis, but most follicles might not grow into mature follicles. These results strongly suggest that the strain difference in ovarian function of these two Hatano rats is due to the difference in the regulation of hypothalamo-hypophyseal system for gonadotropins secretion.