Follicular Phase Of Estrous Cycle Research Articles

Histological, immunohistochemical and serological investigations of the ovary during follicular phase of estrous cycle in Saidi sheep

BackgroundSaidi sheep are the most abundant ruminant livestock species in Upper Egypt, especially in the Assiut governorate. Sheep are one of the most abundant animals raised for food in Egypt. They can convert low-quality roughages into meat and milk in addition to producing fiber and hides therefore; great opportunity exists to enhance their reproduction. Saidi breed is poorly known in terms of reproduction. So this work was done to give more information on some hormonal, oxidative, and blood metabolites parameters in addition to histological, histochemical and immunohistochemical investigations of the ovary during follicular phase of estrous cycle. The present study was conducted on 25 healthy Saidi ewes for serum analysis and 10 healthy ewes for histological assessment aged 2 to 5 years and weighted (38.5 ± 2.03 kg).ResultsThe follicular phase of estrous cycle in Saidi sheep was characterized by the presence of ovarian follicles in different stages of development and atresia in addition to regressed corpus luteum. Interestingly, apoptosis and tissue oxidative markers play a crucial role in follicular and corpus luteum regression. The most prominent features of the follicular phase were the presence of mature antral (Graafian) and preovulatory follicles as well as increased level of some blood metabolites and oxidative markers. Here we give a new schematic sequence of ovarian follicles in Saidi sheep and describing the features of different types. We also clarified that these histological pictures of the ovary was influenced by hormonal, oxidative and blood metabolites factors that characterizes the follicular phase of estrous cycle in Saidi sheep.ConclusionThis work helps to understanding the reproduction in Saidi sheep which assist in improving the reproductive outcome of this breed of sheep. These findings are increasingly important for implementation of a genetic improvement program and utilizing the advanced reproductive techniques as estrous synchronization, artificial insemination and embryo transfer.

Gene expression in the amygdala and hippocampus of cyclic and acyclic gilts.

Age at first estrus is the earliest phenotypic indicator of future reproductive success of gilts. Prebreeding anestrus is a major reason for reproductive failure leading to culling of replacement gilts. The two types of prebreeding anestrus are delay in attaining puberty (prepubertal anestrus, PPA) and silent ovulation (behavioral anestrus, BA). Neural tissues such as amygdala and hippocampus play a major role in regulating sexual behavior, social interactions, and receptivity to males. Differences in gene expression in the amygdala and hippocampus of gilts were analyzed in three comparisons: 1) PPA cases and cyclic controls at follicular phase of estrous cycle, 2) BA cases and cyclic controls at luteal phase of estrous cycle, and 3) gilts at different stages of the ovarian cycle (cyclic gilts at follicular phase and luteal phase of estrous cycle) to gain functional understanding of how these rarely studied tissues may differ between pubertal phenotypes and different stages of the estrous cycle of gilts. Differentially expressed genes (DEG) between PPA and BA cases and their respective cyclic controls were involved in neurological and behavioral disorders as well as nervous system functions that could directly or indirectly involved in development of behaviors related to estrus. The comparison between cyclic follicular and luteal phase control gilts identified the greatest number of DEG in the hippocampus and amygdala. These DEG were involved in adult neurogenesis and neural synapse (e.g., GABAergic, dopamine, cholinergic), suggesting that these tissues undergo structural changes and synaptic plasticity in gilts. This is the first report to demonstrate that the stage of estrous cycle is associated with dynamic changes in gene expression within porcine hippocampus and amygdala and indicates a role of gonadal steroids in regulating their biology.

Free-living Capybaras (Hydrochoerus hydrochaeris) in an Urban Area in Brazil - Biochemical and Hematological Parameters

Background: Capybaras have found favorable conditions for survival and reproduction in green urban environments. In recent years, the population of these large rodents has been increasingly abundant in several brazilian cities such as Uberlândia, a municipality of the southeastern region with a Cerrado biome. Capybaras are important in the Brazilian Spotted Fever epidemiological chain, by amplifying infection rates of the vector population. However, knowledge of this host´s physiology is scarce. Thus, the aim of this work was to describe hematological and biochemical parameters of free-living capybaras groups in urbanized areas in the city of Uberlândia, Minas Gerais State, Brazil.Materials, Methods & Results: Capybaras were captured in 4 different locations of Uberlândia city, Minas Gerais state, including 1 Condominium (P1), 1 Private Market Garden (P2), 1 Private Club (P3) and 1 Municipal Park (P4). The animals were baited into an octagonal iron corral and chemically contained with anesthetic darts. After sedated, blood was collected from the femoral vein in tubes with and without EDTA. Biochemical evaluation, hematological analysis with differential leukocyte counts and search for Dirofilaria sp. were done. The blood count and biochemistry values obtained from animals of different ages, sex and sectors (P1, P2, P3 and P4) were submitted to the Shapiro-Wilk normality test, considering 95% significance. Values that had a normal distribution were subjected to ANOVA tests followed by Student's t-test. Values that did not follow normality were submitted to the Kruskal-Wallis test, to obtain a P-value, with a significance level of 95%. A total of 19 capybaras were captured: 4 in P1, 6 in P2, 4 in P3 and 5 in P4. From the 19 animals, 13 were females (68.42%) and 6 were males (31.57%), 12 adults (63.15%) and 7 juveniles (36.84%). Apart from occasional skin scars and moderate to intense Ambyomma spp. tick infestations, all captured animals were healthy on a broad examination. From 5 animals captured in P4, despite the use of anticoagulant, blood from 4 animals clotted fast. No microfilariae were found in the thick drop test in any of the 19 animals sampled, and in 2 adult female capybaras captured in P1, Kurloff cells were observed. Hematological and biochemical values presented no major differences when comparing sex and age. Nevertheless, differences in liver and kidney profile were observed between the capybara groups, including ALT, alkaline phosphorus, BUN and creatinine.Discussion: Blood from 4 animals clotted fast, despite the use of EDTA tubes. Blood clotting of samples with anticoagulant in this work could be associated with some physiological features inherent to capybaras. Many attempts were required to obtain enough blood from each individual due to the rapid hemostasis, what come in accordance with reports in literature. Kurloff cells were observed in 2 adult female capybaras captured in P1, which can be found in peripheral blood of female rodents during follicular phase of estrous cycle. Hematological and biochemical values differences in liver enzymes such as ALT and alkaline phosphorus, and kidney profile enzymes including BUN and creatinine could be associated to capture stress or dietetic variation between groups. Despite statistical relevant, the values were still in accordance with other works, although comparisons should be done with caution since various environments exert a diverse array of stimulus upon the animals such as parasitic, infective, stress, nutritional, social and undoubtedly blood parameters mirror them. In conclusion, this work contributes to the standardization of free-living capybaras' physiological parameters in urban areas.Keywords: capybaras, physiological parameters, enzymatic parameters, green urban environment, capture stress, fauna, biomes.

Comparative Plasma Endocrine, Metabolic and Mineral Profile of Cyclic, Acyclic, Endometritic and Pregnant Buffaloes

Circulating concentrations of hormones, metabolites, and minerals reflect the physio-pathological status of reproduction in animals. This study was carried out on infertile (anestrus, endometritic), normal healthy cyclic and pregnant buffaloes to evaluate the comparative plasma progesterone (P4) and estrogen (E2) hormones, plasma total protein, total cholesterol, calcium, and phosphorus profile. The study showed higher mean plasma E2 and lower P4 levels in the follicular phase of estrous cycle in buffaloes. Significantly (p less than 0.05) higher mean plasma P4 level and lower E2 levels were recorded during the luteal phase and in endometritic and pregnant buffaloes. Total plasma protein concentration was non-significantly higher in normal cyclic than acyclic and endometritic buffaloes. It was also comparatively lower in buffalo with 9 months of pregnancy than 3 and 6 months of pregnancy. The mean plasma total cholesterol level was significantly (p less than 0.05) higher in pregnant than acyclic and endometritic buffaloes. Cyclic buffaloes had significantly (p less than 0.05) higher mean plasma calcium levels than acyclic buffaloes. Plasma phosphorus concentration, however, did not show any significant difference between different stages of the reproductive cycle.

Immunohistochemical localization of estrogen receptor alpha (ERα) in the oviduct of Indian buffalo during follicular and luteal phases of estrous cycle.

The localization and distribution of estrogen receptor alpha (ERα) in different segments of oviduct of buffalo during follicular and luteal phases of estrous cycle were investigated using immunohistochemistry. Tissue samples from the different segments of oviduct from 12 buffaloes (six each during follicular and luteal phases of estrous cycle) were collected from slaughter house after assessing the gross morphology of ovaries. In addition, blood samples were collected from the animals before slaughter to estimate levels of estrogen and progesterone hormones. The tissue distribution of estrogen receptor was determined by immunohistochemical technique using one-step polymer HRPO staining system. The estrogen receptor was localized in the lamina epithelialis, propria submucosa, tunica muscularis, and tunica serosa. The maximum localization was observed in the lamina epithelialis, where both ciliated and secretory cell types were positive for ERα. Percentage of positive cells varied during the follicular and luteal phases of estrous cycle. The lining epithelium of oviductal glands was also intensely positive for ERα. No immunostaining was observed in any tunic of the oviduct when the primary antibody was replaced by antibody diluent or buffer, and it served as negative control. The data showed that highest immune positive cells were observed in the ampulla region of the oviduct and these cells were lowest in the utero-tubal junction (p < 0.05). Infundibulum, ampulla, and isthmus showed a higher percentage of ERα-positive cells during follicular phase of estrous cycle as compared with those of the luteal phase of estrous cycle (p < 0.05). There was no significant difference in the percentage positive cells during the two phases of estrous cycle in the utero-tubal junction. Immunogold labeling with anti-ERα antibody confirmed the findings of immunohistochemical study at subcellular level. The higher expression during the follicular phase was directly correlated with the level of estrogen hormone.

Scanning Electron Microscopic Study on Oviduct of jaffrabadi Buffalo during Follicular Phase

The present study was conducted on oviduct of adult Jaffrabadi buffaloes during follicular phase of estrous cycle. Study revealed that the oviductal mucosa showed large number of longitudinal folds which were connected by transverse folds, lined with ciliated and non-ciliated cells. Lining epithelial of infundibulum was mainly consist of ciliated cell with few non-ciliated cells. Ampullary region in the follicular phase showed extensive ciliation similar to infundibulum. Isthmus showed less ciliated cells as compared to infundibulum and ampulla. ।

Oviduct morphology and estrogen receptors ERα and ERβ expression in captive Chinchilla lanigera (Hystricomorpha: Chinchillidae)

Chinchilla lanigera is a hystricomorph rodent from South America whose reproductive biology presents particular characteristics that distinguishes it from other Rodentia species, such as low reproductive rate, seasonal breeding pattern, and long estrous cycle. Nevertheless, reproductive features in female chinchillas are still poorly investigated, with a scarce knowledge concerning the estrous cycle and the histology of reproductive organs. In this study, we investigate the morphology, histomorphometry, secretory activity, and immunolocalization of estrogen receptors ERα and ERβ in oviducts of nulliparous chinchillas, euthanized at fall season in Brazil. Follicular phase of estrous cycle of all studied animals was characterized by ovary and uterine morphology inspection, as well as vaginal cytology. Similar to other mammals, the oviduct wall of infundibulum, ampulla and isthmus was composed of mucosa, muscle, and serosa layers. Morphometric data of oviduct layers were used for identifying each oviduct segment. In the follicular phase, the oviduct was characterized by intense secretory activity, mainly in the ampulla, and expression of ERα and ERβ throughout the oviduct epithelium. Both ERα and ERβ were also detected in the connective tissue and smooth muscle cells. Our findings point out to the important role of estrogen in this female organ. Similar wide distribution of both ER proteins has been described for human Fallopian tube. Taken together, our data add to the understanding of the reproductive biology of female chinchillas, and may assist in the intensive breeding of this species and any eventual endeavor for conservation of chinchillas in the wild.

MicroRNA Expression Profile in Bovine Granulosa Cells of Preovulatory Dominant and Subordinate Follicles during the Late Follicular Phase of the Estrous Cycle.

In bovine, ovarian follicles grow in a wave-like fashion with commonly 2 or 3 follicular waves emerging per estrous cycle. The dominant follicle of the follicular wave which coincides with the LH-surge becomes ovulatory, leaving the subordinate follicles to undergo atresia. These physiological processes are controlled by timely and spatially expressed genes and gene products, which in turn are regulated by post-transcriptional regulators. MicroRNAs, a class of short non-coding RNA molecules, are one of the important posttranscriptional regulators of genes associated with various cellular processes. Here we investigated the expression pattern of miRNAs in granulosa cells of bovine preovulatory dominant and subordinate follicles during the late follicular phase of bovine estrous cycle using Illumina miRNA deep sequencing. In addition to 11 putative novel miRNAs, a total of 315 and 323 known miRNAs were detected in preovulatory dominant and subordinate follicles, respectively. Moreover, in comparison with the subordinate follicles, a total of 64 miRNAs were found to be differentially expressed in preovulatory dominant follicles, of which 34 miRNAs including the miR-132 and miR-183 clusters were significantly enriched, and 30 miRNAs including the miR-17-92 cluster, bta-miR-409a and bta-miR-378 were significantly down regulated in preovulatory dominant follicles. In-silico pathway analysis revealed that canonical pathways related to oncogenesis, cell adhesion, cell proliferation, apoptosis and metabolism were significantly enriched by the predicted target genes of differentially expressed miRNAs. Furthermore, Luciferase reporter assay analysis showed that one of the differentially regulated miRNAs, the miR-183 cluster miRNAs, were validated to target the 3´-UTR of FOXO1 gene. Moreover FOXO1 was highly enriched in granulosa cells of subordinate follicles in comparison with the preovulatory dominant follicles demonstrating reciprocal expression pattern with miR-183 cluster miRNAs. In conclusion, the presence of distinct sets of miRNAs in granulosa cells of preovulatory dominant and subordinate follicles supports the potential role of miRNAs in post-transcriptional regulation of genes involved in bovine follicular development during the late follicular phase of the estrous cycle.

Changes in uterine protein secretion during luteal and follicular phases and detection of phosphatases during luteal phase of estrous cycle in buffaloes ( Bubalus bubalis)

Changes in uterine proteins during different reproductive states and their functional significance though known in other species have not been established in buffaloes. An attempt has been made to unravel the changes in composition of buffalo uterine secretion with growth and regression of corpora-lutea during early, mid and late luteal and follicular phase of estrous cycle using gel filtration and electrophoresis techniques. Also the phosphatases activities in luteal phase uterine secretions have been studied. Gel filtration chromatography analysis revealed a protein peak in void volume of the column, the intensity of which was more in all the luteal phase samples than follicular phase samples. Alkaline phosphatase was also found eluted in the void volume. The other three uterus-specific peaks (Peaks V–VII) were detected below 13.7 kd molecular weight. There were at least five peaks of acid phosphatases activity in chromatogram. Silver staining of SDS-PAGE gel detected as many as 40 protein bands in the uterine fluid of which nine proteins were glycoproteins. Molecular weight (MW) comparison revealed the major protein band at 66 kd which could be serum albumin. Comparison of uterine proteins with serum protein bands revealed a 93.5 kd glycoprotein in buffalo serum that did not appear in uterine fluid and at least 11 uterus-specific protein bands (506, 470, 241, 114, 49, 38, 33, 26, 19.2, 16, and 14.3 kd). The 38 and 19.2 kd bands were luteal-stage specific. Intense periodic acid Schiff's (PAS) stained bands in uterine proteins compared to serum indicated glycosylation process in endometrial epithelial cells. The study suggested that buffalo uterine secretion contained mainly serum and several uterus-specific proteins of which few were luteal phase specific. Further study on characterizing the unique or most abundant proteins and defining their role in uterine functions would help to address the cause of low reproduction rate in buffaloes.

Plasma Concentrations of Ir-inhibin, Inhibin A, Inhibin pro-αC, FSH, and Estradiol-17β During Estrous Cycle in Mares and Their Relationship with Follicular Growth

The relationship among plasma levels of immunoreactive (ir)-inhibin, inhibin A, inhibin pro-alphaC, FSH, estradiol-17beta and follicular growth were investigated during the normal estrous cycle in mares. Seven mares were used for two successive normal estrous cycles. Follicular diameters and ovulation were obtained by transrectal ultrasonography, and blood samples were collected daily by jugular venipuncture for hormonal assay. The results showed that inhibin A was inversely correlated (r = -0.59, p < 0.0001) with FSH indicating its contribution to negative feedback control of FSH secretions from the pituitary gland. Estradiol-17beta increased during the follicular phase reaching a peak (37.9 +/- 3.8 pg/mL) 2 d before ovulation. Estradiol-17beta was positively correlated (r = 0.78, p < 0.0001) with inhibin A. The high levels of inhibin A and estradiol-17beta were associated with the growth of the preovulatory dominant follicle and inversely correlated with FSH suggesting that both hormones are products of the large dominant follicles and were responsible for the decline in FSH secretion during the follicular phase of estrous cycle. In conclusion, an inverse relationship between inhibin A and FSH was clearly demonstrated indicating that inhibin A has a key role in the negative feedback control of FSH from the pituitary gland. In addition, inhibin A and estra-diol-17beta secretions were associated with the growth of the preovulatory dominant follicle and were positively correlated.

Follicular atresia and LH concentrations during the follicular phase of the estrous cycle in the goat (Capra hircus).

The objective of the study was to identify the effects of LH on the final follicle maturation process as well as the incidence of atresia during the follicular phase of the goat's estrous cycle. In Experiment 1, concentrations of the LH were measured during the follicular phase of a synchronized cycle in 8 Canary goats. In Experiment 2, the same animals were synchronized again. On each day of a 4-day experimental period (day 0 = day of sponges withdrawal), 2 of the goats were bilaterally ovariectomized. Follicles with a diameter > 1 mm were dissected out to obtain qualitative histological data in normal, early atretic I, early atretic II, advanced atretic I and advanced atretic II follicles. The total interval from sponge withdrawal to LH peak was 77.5 +/- 9.8 h. LH peak concentration averaged 44 +/- 5.3 ng/ml and the mean length of the preovulatory surge (amounts over 10 ng/ml) was 8.9 +/- 0.9 h. During the total follicular phase, there were more atretic follicles than normal follicles (58 vs. 30, P < 0.05). The number of early and advanced atretic follicles was similar. There were more early atresia I than early atresia II follicles (23 vs. 6, P < 0.05). On day 2, the number of advanced atretic follicles was greater than early atretic follicles (10 vs. 4, P < 0.05). There was an increase in the number of early atretic follicles from day 2 to day 4 (4 vs. 9, P < 0.05), which was consistent with the effects of the preovulatory LH surge.

A role for estradiol in enhancing luteinizing hormone pulse frequency during the follicular phase of the estrous cycle of sheep.

Experiments were conducted to test the hypothesis that the increased frequency of LH pulses during the follicular phase of the sheep estrous cycle can be explained by the withdrawal of progesterone. This steroid imposes a profound inhibition of LH pulse frequency in the luteal phase. Experimental ewes were ovariectomized in the late luteal phase of the estrous cycle and divided into three groups: 1) no estradiol provided; 2) basal estradiol maintained at 1-2 pg/ml by small sc Silastic estradiol implants; and 3) peak estradiol of 5-6 pg/ml provided by larger estradiol implants. Control ewes had intact ovaries; their follicular phases were synchronized by insertion and subsequent removal of progesterone implants. LH pulses were monitored beginning 24 h after ovariectomy of experimental ewes or progesterone implant removal from intact control ewes. In the follicular phase controls, LH pulse frequency increased 3- to 4-fold after progesterone withdrawal, reaching up to two pulses per h. When estradiol was not provided after ovariectomy of experimental ewes, LH pulse frequency also increased, but not to the extent seen in the follicular phase control. This high frequency was achieved, however, in experimental ewes treated with either basal or peak estradiol. Both estradiol treatments also reduced LH pulse amplitude. These results fail to support the hypothesis that the high frequency of LH pulses in the follicular phase is solely a consequence of progesterone withdrawal at luteolysis. Rather, they suggest that estradiol (but not necessarily rising estradiol) also contributes to the high frequency pulses of LH that occur in the ewe at this time.