Cell-specific localisation of apoptosis in the bovine ovary at different stages of the oestrous cycle

Apoptosis was localized in all ovarian cell types of 23 cows in various stages of the oestrous cycle, using the detection of active caspase-3, in situ end labelling (TUNEL) and DNA fluorescent staining (DAPI). Very few apoptotic cells were found in primordial, primary, secondary and vital tertiary follicles. In contrast, apoptosis in atretic tertiary follicles was much more frequent, and high apoptotic scores were recorded when using the TUNEL technique and lower scores with the caspase-3 assay. Cystic atretic follicles showed in general a higher apoptotic score than obliterative atretic follicles, with intermediate to high scores in granulosa cells and lower scores in theca cells. In corpora lutea, large and small lutein cells had intermediate to high scores using the caspase-3 assay, and intermediate to low scores using the TUNEL assay. Irrespective of the detection method, the scores were higher in lutein cells than in the capsular stroma cells. In all ovarian structures examined, variations in apoptotic scores were seen in the different cycle stages, suggesting a cycle-dependent influence on apoptosis, although correlations with plasma progesterone concentrations were low.     

Effect of cadmium chloride on the ovulation and structure of ovary in the inbred KP and CBA mice strains

A single dose of cadmium chloride (2.2 mumol/100 g of body weight) brought about in the sensitive KP strain alterations of the ovarian structure and disturbances in the ovarian cycle manifested by a prolongation of diestrus. Following cadmium administration and increase in the amount of atretic follicles, especially those showing stages 1I and 2II of degeneration, was observed in the ovaries of KP mice. The corpora lutea contained numerous degenerated cells and were infiltrated by abundant connective tissue cells. The used dose of cadmium chloride showed no influences upon progesterone level. The absence of changes in the ovarian morphology and in the duration of the oestrus cycle in CBA females suggest that this strain is resistant to cadmium chloride.     

Changes in ovarian follicles and in vitro sex hormone release in the lizard Podarcis sicula sicula

An in vitro superfusion method was used to test sex hormone release from different kinds of ovarian follicle (growing follicles, postovulatory follicles, and atretic follicles) in the lizard Podarcis sicula sicula. Sex hormone output changes with the stage of follicle evolution and sexual cycle. Previtellogenetic follicles prevail in early-spring quiescent ovaries and secrete mainly progesterone, which is probably utilized at that phase to delay ovarian resumption. In the active ovary, progesterone output from previtellogenetic follicles decreases, whereas vitellogenetic follicles produce a significant amount of 17β-estradiol, which is necessary for sustaining vitellogenin synthesis by the liver and oviduct growth. As follicles become ripe, progesterone production is resumed, and it increases in young postovulatory follicles. This is in line with the functions assigned to the hormone at that phase of the sexual cycle, i.e., the induction of oocyte maturation and the regulation of egg retention in the oviduct. Postovulatory follicles can also synthetize 17β-estradiol. After oviposition, this hormone, which is secreted by the old postovulatory follicles, can reinitiate vitellogenin synthesis, allowing the development of a new oocyte set. Our data confirm that active, although ephemeral, corpora lutea are also formed in oviparous species. A limited contribution to ovarian sex steroid production derives also from atretic follicles, at least at the early stages of the breeding cycle. © 1993 Wiley-Liss, Inc.     

Levels of messenger ribonucleic acid encoding cholesterol side-chain cleavage cytochrome P-450, 17 alpha-hydroxylase cytochrome P-450, adrenodoxin, and low density lipoprotein receptor in bovine follicles and corpora lutea throughout the ovarian cycle

To investigate the molecular basis for the pattern of ovarian steroid production during the bovine estrous cycle, the relative levels of mRNA specific for cholesterol side-chain cleavage cytochrome P-450, 17 alpha-hydroxylase cytochrome P-450, adrenodoxin, and low density lipoprotein receptor were determined in ovarian antral follicles of differing size (less than 3-18 mm) and corpora lutea from the early, early-mid, late-mid, and regressionary stages. Total and poly(A)+ RNA was size-fractionated on agarose-formaldehyde gels, transferred to nylon filters and hybridized to specific 32P-labeled probes. The levels of mRNAs for the rate-limiting enzymes in the conversion of cholesterol into progesterone, namely cholesterol side-chain cleavage cytochrome P-450 and its electron donor, adrenodoxin, were higher in corpora lutea than in follicles. Conversely the levels of mRNA specific for the key regulatory enzyme in the conversion of pregnenolone or progesterone to androgen, namely 17 alpha-hydroxylase cytochrome P-450, were high in all antral follicles examined but were low in young corpora lutea and undetectable in more mature corpora lutea. Low density lipoprotein receptor mRNA was detectable in antral follicles and corpora lutea but the levels were greater in corpora lutea. These results suggest that the pattern of changes in steroid hormone biosynthesis during the bovine estrous cycle and in the ovarian content of steroidogenic enzymes is related to and probably dependent upon the pattern of change in levels of mRNAs for steroidogenic enzymes and related proteins.     

Localization of an activin/activin receptor system in the porcine ovary.

The aim of this study was to locate a possible activin/activin receptor system within porcine ovaries containing functional corpora lutea. In situ hybridization was used to assess the gene expression of beta(A)- and beta(B)-activin subunits, and immunohistochemical studies were done to detect activin-A protein and activin receptor type II. mRNA expression of the beta(A)- and beta(B)-activin subunits was found in the granulosa from the unilaminar follicle stage onward, in the developing thecal layer of multilaminar and small antral follicles, in the theca interna of mid-sized antral follicles, in corpora lutea, and in the ovarian surface epithelium. Immunoreactive activin A protein could be detected at the same ovarian sites, but in thecal tissue of small antral follicles only. This protein was also demonstrated at the peripheral zone of oocytes from multilaminar and antral follicles. A positive immunoreaction for activin receptor was found in granulosa cells from multilaminar and older follicles and in oocytes from the earliest stages of follicular development onward. In late multilaminar follicles and in antral follicles, the oolemma was stained. Except for small antral follicles, a positive activin receptor immunoreaction was absent in the follicular theca. Activin receptor immunoreaction was furthermore present in corpora lutea and in the ovarian surface epithelium. It is concluded that, within porcine ovaries containing functional corpora lutea, an activin/activin receptor system is present in all intact follicles, the corpora lutea and the surface epithelium. Within follicles, granulosa and theca cells are the main sites of activin synthesis, while oocytes and granulosa cells are the main activin binding sites.     

Expression of follicle stimulating hormone and luteinizing hormone receptors during follicular growth in the domestic cat ovary

In order to better understand the pituitary regulation of follicular growth in the domestic cat, follicle stimulating hormone (FSH) and luteinizing hormone (LH) receptors (R) were localized and quantified in relation to follicle diameter and atresia using in situ ligand binding on ovarian sections. Expression of FSHR was homogeneous and restricted to follicle granulosa cells from the early antral stage onwards, whereas expression of LHR was heterogeneous on theca cells of all follicles from the early antral stage onward, and homogeneous on granulosa cells of healthy follicles larger than 800 microm in diameter and in corpora lutea. LHR were also widely expressed as heterogeneous aggregates in the ovarian interstitial tissue. Atretic follicles exhibited significantly reduced levels of both FSHR and LHR on granulosa cells, compared with healthy follicles whatever the follicular diameter, whereas levels of LHR on theca cells were lower only for atretic follicles larger than 1,600 microm in diameter. In healthy follicles, levels of FSHR and LHR in all follicular compartments increased significantly with diameter. Although generally comparable to that observed in other mammals, the expression pattern of gonadotropin receptors in the cat ovary is characterized by an early acquisition of LHR on granulosa cells of growing follicles and islets of LH binding sites in the ovarian interstitial tissue.     

中国大鲵闭锁卵泡的显微和超微结构观察

用光镜和电镜观察了中国大鲵卵泡闭锁过程和闭锁小体的显微和超微结构。结果显示 ,大鲵闭锁小体是卵泡细胞侵噬卵母细胞并增殖形成细胞团 ,膜细胞未参与。在大部分卵泡处于缓慢生长期时 ,未发现卵泡闭锁现象 ;在 5、 6月份 ,卵巢内大部分卵母细胞进入卵黄形成前期 ,部分卵泡闭锁 ,但闭锁小体细胞的类固醇激素分泌结构特征不明显 ;在 7、 8月份 ,大多数卵母细胞处于卵黄形成期 ,闭锁小体细胞具有管泡状嵴线粒体、丰富的滑面内质网和脂滴、发达的高尔基体等。这些细胞学特征表明闭锁小体可分泌类固醇激素 ,以调节正常卵子的成熟。在大鲵中观察到的闭锁小体属于排卵前黄体     

Pituitary control of ovarian activity in the lizard, Agama agama

The principal ovarian structures in Agama agama are non-yolky and yolky follicles, corpora lutea and atretic follicles. Hypophysectomy affects all stages of vitellogenesis and follicular atresia results. Atresia involves resorption and digestion of yolk by the granulosa cells, which eventually undergo a fatty degeneration. Immature follicles and corpora lutea are not affected by hypophysectomy.
Injections of 0.2 mg FSH (NIH-FSH-S3 ovine) on alternate days for 14 days not only maintain vitellogenesis in hypophysectomized animals, but also tend to overstimulate the small follicles to synthesize yolk. A similar dose of LH(NIH-LH-SII ovine) fails to maintain vitellogenesis in hypophysectomized animals, while a higher dose of 0.4 mg LH tends to overstimulate the small follicles. An unusual rupture of yolky follicles in FSH injected lizards is reported and a possible development of such follicles into corpora lutea is discussed.     

Interleukin-1 alpha increases thecal progesterone production of preovulatory follicles in cyclic hamsters

Adult cyclic hamsters were used to study the effects of interleukin-1 alpha (IL-1 alpha) on in vitro steroidogenesis in preovulatory follicles. IL-1 alpha increased progesterone secretion by preovulatory follicles during a 24-h incubation in RPMI-1640 medium containing hCG (100 mIU/ml) (progesterone levels: 17.5 +/- 2.2 vs. 10.6 +/- 1.9 ng/follicle/ml, p less than 0.05). IL-1 alpha alone had no effect on follicular steroidogenesis. The source of increased progesterone secretion was the thecae (9.8 +/- 1.0 vs. 5.8 +/- 0.4 ng/2 thecae/ml, p less than 0.01) and not the granulosa cells (6.6 +/- 0.2 vs. 6.8 +/- 0.5 ng/20,000 viable granulosa cells/ml). IL-1 alpha also stimulated production of testosterone in thecae of preovulatory follicles. The follicular progesterone increase was dependent on the time of incubation and dose of IL-1 alpha. IL-1 alpha at 5-50 U/ml maximally stimulated progesterone production in the preovulatory follicles, and no significant effect of IL-1 alpha was observed until the 12th hour of incubation. The effects of IL-1 alpha on in vitro steroidogenesis in preantral follicles, experimentally induced atretic preovulatory follicles, and newly formed corpora lutea were examined. IL-1 alpha in the presence of hCG also significantly increased progesterone secretion by atretic preovulatory follicles. In the incubation of preantral follicles or newly formed corpora lutea, however, IL-1 alpha did not alter steroidogenesis. These results indicate that IL-1 alpha stimulates progesterone secretion by preovulatory follicles and that the target tissue for this effect is the thecal layer.(ABSTRACT TRUNCATED AT 250 WORDS)     

Syndecan-4 expression is associated with follicular atresia in mouse ovary

Ovarian granulosa cells synthesize heparan sulfate proteoglycans (HSPGs), that have anticoagulant properties. Moreover, HSPGs greatly increase in the granulosa cells during follicular atresia. However, the species of ovarian HSPGs have not yet been identified. Syndecan-4 (ryudocan, amphiglycan) is a membrane-spanning HSPG and a member of the syndecan family. Herein, we demonstrate that syndecan-4 is expressed in the granulosa cells of type 4-5b follicles and, most intensely, in those of the atretic follicles in the mouse ovary, as revealed by in situ hybridization. There is no relationship between syndecan-4 expression and age or sexual cycle stage. Compared with syndecan-4 expression, syndecan-1 and -3 are expressed more abundantly in postovulatory follicles and the corpora lutea, but less in the type 4-5b follicles and much less in the atretic follicles. Immunohistochemistry also demonstrates syndecan-4 expression in atretic follicles with apoptosis. The present study has revealed the distinct modes of expression of the syndecan family members, and the association of syndecan-4 expression and apoptosis in ovarian atretic follicles.     

Effect of nutritionally induced liveweight differences on ovulation rates and the population of ovarian follicles in ewes

Differential feeding prior to the onset of the breeding season resulted in mean liveweight differences of 12 kg in two groups of Romney ewes. This difference was maintained while ovulation rates and the population of externally visible ovarian follicles were measured. The ovulation rate at first oestrus was significantly higher in the high liveweight group but there was no difference between groups thereafter. High liveweight ewes had consistently higher mean follicle scores at all stages of the oestrous cycle. Mean follicle score was lower following the third oestrus than following first oestrus (P < 0.01).     

Ovarian histology of the placentotrophic Mabuya mabouya (Squamata, Scincidae)

Ovarian structure and folliculogenesis of females at different reproductive stages are described for the viviparous placentotrophic lizard Mabuya mabouya. The small ovaries have a thin wall formed by the ovarian epithelium and a thin tunica albuginea. One to two germinal beds that contain numerous oogonia and developing primordial follicles are derived from the ovarian epithelium and are next to the ovarian hilum. The ovarian cortex contains follicles at different stages of development, corpora lutea, and atretic follicles. The yolk nucleus and Balbiani complex were not evident in the ooplasm of previtellogenic follicles. The follicular epithelium of these follicles is polymorphic, as in other species of Squamata, but the larger cells are spherical and monolayered rather than pyriform. The zona radiata of the preovulatory follicles is less developed than in lecithotrophic species. These features suggest a decrease in metabolic and absorptive processes during follicular growth. In preovulatory follicles (1.5-1.8 mm diameter), primordial yolk vacuoles and small cortical granules are deposited in the ooplasm instead of fatty yolk platelets, so that only one stage of vitellogenesis is observed. Polyovular atretic follicles occur in some females. Follicular atresia is minimal for preovulatory follicles, but is more frequent in follicles with polymorphic epithelia. In the corpus luteum, the luteal tissue is formed from granulosa cells and luteolysis occurs during the late gastrula -- late neurula embryonic stages. Thus, the maintenance of gestation from the pharyngula to preparturition stages seems to be related to secretion of extraluteal progesterone, possibly of placental origin. These observed ovarian features are related to the high degree of placental complexity of this species and show that the evolution of advanced placentotrophy in species of this lineage has been accompanied by concomitant changes in ovarian function.     

The maternal recognition of pregnancy in mammals

Progesterone secreted by the corpora lutea stimulates uterine secretion of nutrients required for embryonic growth. But progesterone also blocks maturation of ovarian follicles and oestrous behaviour. When conception fails, therefore, the corpora lutea must lyse, in order to allow a second ovulation and oestrus, while in pregnancy the corpora lutea must be maintained. A number of different endocrine mechanisms exist to ensure the corpora lutea are controlled appropriately depending on pregnancy status; among the best studied of these are the secretion by the developing conceptus of interferons (in ungulates) or chorionic gonadotropins (in primates). These and other mechanisms are reviewed.     

A review on the morphology of ovarian follicles in elasmobranchs: A case study in Rhizoprionodon taylori

The identification of the elasmobranch secondary ovarian follicles and their function can be challenging and the inconsistent use of terminology derived from other taxa is a matter of ongoing debate. In this study, the available information on the histology of the elasmobranch secondary ovarian follicles derived from atresia (preovulatory follicles) or ovulation (postovulatory follicles) is reviewed highlighting their morphology and steroidogenic capacity. Based on this literature review, the ovarian follicles of the Australian sharpnose shark Rhizoprionodon taylori were classified according to their preovulatory or postovulatory origin. Two types of secondary follicles originating from atresia of developing follicles (atretic previtellogenic follicles) and ripe follicles (atretic vitellogenic follicles), and one type of postovulatory follicle were identified throughout the reproductive year of this species. Morphological similarities of the elasmobranch secondary ovarian follicles and their variations in different species denote the difficulty to classify them. Given the multiple origins of ovarian follicles, their poorly understood functions and capacity to supply steroids, visual identification of these structures and the use of terminology derived from mammalian and other vertebrate studies (with the exception of the corpora lutea as a temporary endocrine gland) is not advisable. J. Morphol. 278:486–499, 2017. © 2017 Wiley Periodicals, Inc.     

Localization of androgen receptor in the follicle and corpus luteum of the primate ovary during the menstrual cycle

Ovarian androgens may act locally to modulate follicular and luteal function in various species. This study examined the distribution of androgen receptors within the primate ovary throughout the menstrual cycle. Ovaries were collected from rhesus and cynomolgus monkeys during the early, mid-, and late (n = 3-5 per stage) follicular and luteal phases of the cycle. The tissues were processed for indirect immunocytochemical localization of androgen receptors with a specific monoclonal antibody against human androgen receptor (AN1-15). In addition, ovaries (n = 3) were collected from rhesus monkeys for biochemical detection of androgen receptor using 3H-androgen and AN1-15. Specific immunocytochemical staining, as determined by comparing adjacent tissue sections incubated with either AN1-15 or a nonspecific control antibody, was exclusively nuclear. Androgen receptor was detected in the germinal epithelium and ovarian stroma at all stages of the cycle. The thecal and granulosa cells of growing follicles, and of many but not all atretic follicles, contained androgen receptors. Luteinizing granulosa cells of the periovulatory follicle and luteal cells from the early and midluteal phase stained intensely for androgen receptor. Regressing corpora lutea of the late luteal phase also stained for androgen receptor; however, fully regressed corpora lutea in the early follicular phase of the next cycle did not exhibit receptor staining. Luteal cells that were androgen receptor-positive also stained histochemically for the presence of 3 beta-hydroxysteroid dehydrogenase. Sucrose gradient analysis with radiolabeled androgen demonstrated a shift in the androgen receptor peak in monkey ovarian tissue upon addition of AN1-15, confirming the presence of androgen receptor.(ABSTRACT TRUNCATED AT 250 WORDS)     

Coexpression of adrenomedullin and its receptors in the reproductive system of the rat: effects on steroid secretion in rat ovary

The present study demonstrates the expression of adrenomedullin (ADM) in the reproductive system of the female rat and its effect on the secretion of estradiol and progesterone. Ovarian ADM and Adm mRNA levels were decreased at estrus, whereas oviductal Adm mRNA levels were low at proestrus. Both tissues were shown to coexpress mRNAs encoding the calcitonin receptor-like receptor and receptor activity-modifying protein 1 (Ramp1), Ramp2, and Ramp3. Gel filtration chromatography of ovarian extracts showed two peaks, with the predominant one eluting at the position of authentic rat ADM (1-50) at estrus and at the position of ADM precursor at diestrus. Positive ADM immunostaining was localized in the granulosa and theca cells of the follicle and corpora lutea of the ovary. Adrenomedullin inhibited FSH-induced estradiol secretion in 2-day-old follicles and also suppressed eCG-stimulated progesterone release in corpora lutea. The inhibitory effect of ADM on the follicles and the corpora lutea was abolished by calcitonin gene-related peptide (8-37) and ADM (22-52), respectively. The presence of ADM and the gene expression of ADM and its receptor components in the female reproductive system suggest a paracrine effect of ADM on ovarian steroidogenesis.     

The endothelin system in human and monkey ovaries: in situ gene expression of the different components

The endothelin system is composed of three endothelin isoforms (ET-1, ET-2, and ET-3), the endothelin receptors ETA and ETB, and the endothelin-converting enzyme (ECE). Besides having a major vasoactive role, endothelins have roles in different cell types at a local level. We investigated the presence of the different components of the endothelin system in primate ovaries. Human ovaries and gonadotropin-stimulated monkey ovaries were studied using immunohistochemistry for endothelin, and in situ hybridization with probes for ET-1, ET-2, ET-3, ETA and ETB receptors, and ECE. ET-1 and ETA receptors were detected in endothelial cells and vascular smooth muscle cells, respectively, in stromal vessels adjacent to follicles and corpora lutea. ETB receptors and ET-1 were found in the endothelial cells of capillaries of corpora lutea. ECE was present in internal theca cells of secondary, de Graaf, atretic follicles, and in luteinized granulosa cells of the corpora lutea. The endothelin system components are present in or around the follicles of human and monkey ovaries. Although the components are not expressed in the same cell types, they are synthesized, mainly in follicles, by cells that are in close proximity. Thus, the endothelin system could act in a paracrine manner. ECE expression in steroid-producing cells changes its compartmentalization during follicle maturation.