The relationship of follicle atresia to follicle size, oocyte recovery rate on aspiration, and oocyte morphology in the mare

Oocytes were collected by aspiration of follicles from horse ovaries obtained at surgery or post-mortem. The oocytes were classified according to morphology of the ooplasm and cumulus. The size of the corresponding follicles was measured, and sections of the follicles were fixed and examined histologically to determine the stage of viability or atresia. In Part 1, 11 pairs of ovaries were examined and all follicles were sectioned; in Part 2, 9 pairs of ovaries were examined and only those follicles from which oocytes were recovered were sectioned. The number of follicles examined per pair of ovaries in Part 1 (average +/- SD) was 12.9 +/- 4.1. The proportion of follicles that were viable increased with increasing follicular size (P < 0.01); the percentage of viable follicles was 21, 42 and 83% for follicles < 10 mm, 10 to 19 mm, and >/= 20 mm in diameter, respectively. The overall oocyte recovery rate on aspiration of follicles was 46%. There was no significant difference in the oocyte recovery rate between viable and atretic follicles. A significantly higher proportion of oocytes recovered from viable follicles had granular ooplasm (64 vs 39%; (P < 0.05); whereas significantly more oocytes from atretic follicles had a misshapen or dense ooplasm (23 vs 6%; P < 0.05), or an expanded or pyknotic cumulus (24 vs 6%; P < 0.05). The most common cumulus morphology (63% of oocytes from viable follicles and 48% of oocytes from atretic follicles) was presence of only the corona radiata. Only 11% of oocytes from viable follicles and 9% of oocytes from atretic follicles had a complete cumulus present.     

The Role of DmCatD,a Cathepsin D-Like Peptidase,and Acid Phosphatase in the Process of Follicular Atresia in Dipetalogaster maxima (Hemiptera: Reduviidae), a Vector of Chagas' Disease

In this work, we have investigated the involvement of DmCatD, a cathepsin D-like peptidase, and acid phosphatase in the process of follicular atresia of Dipetalogaster maxima, a hematophagous insect vector of Chagas’ disease. For the studies, fat bodies, ovaries and hemolymph were sampled from anautogenous females at representative days of the reproductive cycle: pre-vitellogenesis, vitellogenesis as well as early and late atresia. Real time PCR (qPCR) and western blot assays showed that DmCatD was expressed in fat bodies and ovaries at all reproductive stages, being the expression of its active form significantly higher at the atretic stages. In hemolymph samples, only the immunoreactive band compatible with pro-DmCatD was observed by western blot. Acid phosphatase activity in ovarian tissues significantly increased during follicular atresia in comparison to pre-vitellogenesis and vitellogenesis. A further enzyme characterization with inhibitors showed that the high levels of acid phosphatase activity in atretic ovaries corresponded mainly to a tyrosine phosphatase. Immunofluorescence assays demonstrated that DmCatD and tyrosine phosphatase were associated with yolk bodies in vitellogenic follicles, while in atretic stages they displayed a different cellular distribution. DmCatD and tyrosine phosphatase partially co-localized with vitellin. Moreover, their interaction was supported by FRET analysis. In vitro assays using homogenates of atretic ovaries as the enzyme source and enzyme inhibitors demonstrated that DmCatD, together with a tyrosine phosphatase, were necessary to promote the degradation of vitellin. Taken together, the results strongly suggested that both acid hydrolases play a central role in early vitellin proteolysis during the process of follicular atresia.     

Gamma-radiation-induced follicular degeneration in the prepubertal mouse ovary

Prepubertal mice were whole-body irradiated with a mean lethal dose (LD50) of gamma-radiation using a 60Co source with a total dose of 7.2 Gy and a dose rate of 12.0 cGy/min. At day 0 before the irradiation and at day 1, 2, and 3 after the irradiation, the ovaries were collected and the morphological changes were assessed. The ratios (%) of atretic or polymorphonuclear leukocytes (neutrophil)-infiltrated follicles in the largest cross sections were calculated. In the early atretic follicle of the control mouse ovary, both apoptotic and mitotic cells were observed and occasionally neutrophils were infiltrated into the follicle cavity. However, in the atretic follicles 2 days post-irradiation, numerous cell fragments, apoptotic cells and bodies, and especially, a number of neutrophils were observed. In the non-irradiated control, the ratios of atretic follicles were 58.0+/-8.6 and 27.3+/-11.2 (mean+/-S.E.M.) in antral and preantral follicles, respectively. The ratios of the number of antral and preantral follicles with one or more neutrophils to the total number of atretic follicles were 29.3+/-12.0. At 2 days post-irradiation, the ratios of atretic follicles were increased to 94.0+/-3.4 and 86.9+/-7.6 in antral and preantral follicles, respectively. The ratios of neutrophil-containing follicles among the atretic one were increased to 65.9+/-11.5 and 57.8+/-15.4 at 2 and 3 days after the irradiation, respectively. Taken together, the present results show that gamma-radiation induces apoptotic and inflammatory degeneration of mouse ovarian follicles. Besides, neutrophils may be involved in the acute atretic degeneration in gamma-irradiated mouse ovarian follicles.     

IGF1 stimulates differentiation of primary follicles and their growth in ovarian explants of zebrafish (<Emphasis Type="Italic">Danio rerio)</Emphasis> cultured <Emphasis Type="Italic">in vitro</Emphasis>

The present study is an attempt to elucidate the involvement of insulin-like growth factor (IGF1) in the differentiation and growth of primary follicles in ovarian explant cultures of zebrafish. Ovaries from adult females were cultured in triplicate sets/treatment group for 15 days at 22°C in the laboratory. Culture medium was supplemented with either insulin (1 ng/mL) or IGF1 (1 ng/mL) or insulin + IGF1 (Experiment 1) or 0.1 or 1.0 or 10 ng/mL of IGF1 (Experiment 2). Ovaries cultured in medium alone served as controls and those fixed at the beginning of the culture as initial controls. Experiments were repeated. On the 16th day ovarian explants were fixed in Bouin’s fluid and processed for paraffin embedding, sections (3 µm) were cut and stained with hematoxylin-eosin. Follicles were classified into 6 stages and atretic follicles (AF). Previtellogenic, vitellogenic and total follicle number was calculated. At the start of the culture, ovaries contained all stages of growing and degenerating follicles. In in vitro cultured control ovaries, vitellogenic follicles underwent atresia, while, primary follicles remained unaffected. Insulin or insulin + IGF1 treated ovaries did not differ significantly while IGF1 exposed ovarian explants had greater (P < 0.05) number of primary follicles compared to controls. IGF1 also caused an increase in the number and growth of primary follicles in a dose dependent manner although; cultures were not supplemented with gonadotrophic hormones. Results suggest that locally derived intra-ovarian IGF1 may have a role in the differentiation and growth of primary follicles in zebrafish ovary.     

Quantitative determination of follicle size distribution in the guinea pig ovary after hemicastration and PMSG treatment

In order to investigate the action point of intraphysiological or supraphysiological elevation of FSH during the preovulatory period on follicular development, adult guinea pigs underwent unilateral ovariectomy on days 10, 12 and 14 of the estrous cycle (N = 6 each group). Thereafter, guinea pigs were injected twice daily with either vehicle or pregnant mare's serum gonadotropin (PMS). After 2 days, the remaining ovaries were removed. The resected ovaries were fixed, embedded in paraffin, serially sectioned (7 microns) and stained with Azan. All follicles greater than 70 microns were classified by size and atretic stage. The follicular size distribution was not affected by hemicastration at day 10, although the ratio of atretic follicles (greater than 400 microns) decreased from 51% to 32% (P less than 0.01). Hemicastration at day 12 increased the largest nonatretic population (70-99 microns group) from 17% to 26%, and the ratio of atretic follicles (greater than 400 microns) decreased from 35% to 23%. The peak size distribution of follicles was shifted from 70-99 microns to 200-299 microns by PMS, and follicles 600-899 microns in size contained an increased percentage of atresia, which resulted in the bimodal distribution of viable follicles greater than 400 microns. These data suggest that 2 day hemicastration promotes an influx of primordial follicles into growing follicles and suppresses the atretic process by a different mechanism depending on the date of hemicastration in the estrous cycle. Conversely, hemicastration + PMS accelerated viable follicle growth to increase the percentage of atresia.     

Cessation of transition-phase follicle growth in the guinea pig by follicle-regulatory protein

The granulosa cell produces a protein inhibitor of aromatase activity (follicle-regulatory protein: FRP), which recently was purified to homogeneity. To determine the possible involvement of FRP in follicular maturation, we examined the size distribution of follicles and their morphological patterns as well as serum steroid levels after the systemic administration of FRP and/or gonadotropin to guinea pigs, which have 5-6 days between luteolysis and ovulation in a 16-day cycle. FRP was partially purified from porcine follicular fluid by ammonium sulfate precipitation (0-35%), Dye Matrex Orange A Chromatography, dialysis, and lyophylization. To investigate the effect of pregnant mare's serum (PMS) during the periovulatory period in follicular development, adult guinea pigs underwent unilateral ovariectomy on Days 10, 12, and 14 of the estrous cycle (N = 6 each). Guinea pigs were injected twice daily with vehicle or PMS (5 IU) and 2 days thereafter the remaining ovaries were removed. Another group of guinea pigs received, in addition, intraperitoneal injections of FRP (1 mg) each morning from Day 8 of estrus until they were killed. The resected ovaries were fixed, embedded in paraffin, serially sectioned (7 micron), and stained with Azan for comparative study via light microscopy. All follicles greater than 400 micron were classified by size, and the atretic pattern was determined by mural granulosa cell pyknosis and antral sloughing. The distribution of follicular size was not affected by hemicastration at Day 10, although the percentage of total atretic follicles decreased. In the PMS-treated group, there was a significant decrease in the number of viable follicles (700-899 micron) after hemicastration. Also pronounced in follicles of this size was the lack of mid-atretic follicles. After injections of FRP for 3 or 5 days, the overall number of follicles was almost doubled as compared to the number found in the normal ovary. Additionally, there was a significant increase in the percentage of follicles that were recently atretic, although the total percentage of atretic follicles was unchanged. After hemicastration at Day 10 followed by FRP treatment for 2 days, the total percentage of atretic follicles in the remaining ovary decreased to 18% compared with 35% in the normal ovary, 46% in the hemicastrated plus PMS-treated group, and 38% in the hemicastrated and PMS- and FRP-treated group (all p less than 0.01). Treating the hemicastrated animal with PMS increased the percentage of atretic follicles in all groups.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of high doses of retinol acetate on the 3-beta-ol-steroid dehydrogenase and alkaline phosphatase content in mouse ovaries

The author reports on the effects of different doses of retinol acetate on ovarian steroidogenesis. Two groups of CBA/C57BL mice with a mean body weight of 18-20 g received 3.44% oily retinol acetate per os in daily doses of 50 000 and 80 000 IU for 10 days. After completion of the experiments the quick-frozen sections of the ovaries were subjected to a histochemical assay for the content of 3-beta-ol-steroid dehydrogenase and alkaline phosphatase. Administration of 50 000 IU vitamin A was found to stimulate ovarian steroidogenesis. The effect of vitamin A was the most demonstrable in the interstitial tissue, atretic corpora, and, in the internal theca of the follicles. Administration of 80 000 IU retinol acetate inhibited ovarian steroidogenesis. The estrous cycle in animals ceased. Administration of vitamin A (80 000) primarily affected the follicular apparatus of the ovaries, namely the epithelium of the follicles and yellow bodies. At the same time secretory function of atretic corpora and interstitial tissue remained within normal, which was regarded as a compensatory-adaptive mechanism under toxic hypervitaminosis A.     

Development of the polycystic ovarian condition (PCO) in the estradiol valerate-treated rat

A wide range of experimental manipulations results in an anovulatory polycystic ovarian (PCO) condition in the rat. Although PCO has been studied in a number of these models, research has centered on the condition after it is well established rather than as it develops. Consequently, it is still not clear exactly what follicular cysts are or how and why they form. Therefore, we studied the development of PCO in rats treated with estradiol-valerate (EV). In this model, definitive cysts were present 8-9 wk after a single injection of EV. Animals were killed at 5, 11, 16, 21, 28 and 56 days after EV treatment. Serum was assayed for luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Ovaries were weighed and prepared for histologic examination. The ovaries were serially sectioned such that the number and size distribution of normal and atretic follicles could be assessed quantitatively. Oviducts were examined for the presence of ova. Immediately after EV treatment, ovulatory cycles ceased; by 16-20 days posttreatment, all animals exhibited persistent vaginal cornification. Basal concentrations of serum LH and FSH fell to a nadir at 11 days posttreatment, after which both gonadotropins exhibited a trend toward recovery. Within the first 28 days after treatment, ovarian weights declined significantly as did the total number of healthy follicles. Atretic follicles of all sizes were particularly numerous at 16 days. By 28 days, the decline in the number of healthy follicles reached a plateau. Numerous atretic, large secondary follicles were particularly prominent on the background of the decreasing number of normal follicles.(ABSTRACT TRUNCATED AT 250 WORDS)     

Culture and Co-Culture of Mouse Ovaries and Ovarian Follicles

The mammalian ovary is composed of ovarian follicles, each follicle consisting of a single oocyte surrounded by somatic granulosa cells, enclosed together within a basement membrane. A finite pool of follicles is laid down during embryonic development, when oocytes in meiotic arrest form a close association with flattened granulosa cells, forming primordial follicles. By or shortly after birth, mammalian ovaries contain their lifetime’s supply of primordial follicles, from which point onwards there is a steady release of follicles into the growing follicular pool.The ovary is particularly amenable to development in vitro, with follicles growing in a highly physiological manner in culture. This work describes the culture of whole neonatal ovaries containing primordial follicles, and the culture of individual ovarian follicles, a method which can support the development of follicles from an immature through to the preovulatory stage, after which their oocytes are able to undergo fertilization in vitro. The work outlined here uses culture systems to determine how the ovary is affected by exposure to external compounds. We also describe a co-culture system, which allows investigation of the interactions that occur between growing follicles and the non-growing pool of primordial follicles.     

The structure of the spiny mouse (Acomys cahirinus) ovary during development

The study presents the structure of the ovaries of the spiny mouse (Acomys cahirinus) during the first months of life. The ovaries in neonate females exhibit a large number of primordial and primary follicles, sometimes clustered in nests. The growing follicles were also observed within the ovary at that period. The first, early antral follicles appeared in the ovary during the second week of life. In the group of 60-day old females, the structure of the ovaries was characterized by a significant increase in the connective tissue elements. Moreover, ovarian follicles at various stages of development were observed, except for the antral ones with cumulus oophorus. The first mature follicles were identified in 3-month old females. In the ovarian follicles, apoptosis occurs at all stages of follicle development, especially in the early antral follicles. In the atretic follicles, apoptotic cells were identified in the layer of granulosa cells.     

Effect of turmeric on the viability,ovarian folliculogenesis,fecundity, ovarian hormones and response to luteinizing hormone of rabbits

The present study investigated whether dietary turmeric (Curcuma longa L.) can improve rabbit reproduction, ovarian function, growth, or viability. Female New Zealand White rabbits were either fed a standard diet (n=15) or a diet enriched with 5 g (group E1) or 20 g (group E2) turmeric powder per 100 kg feed mixture (n=16 or 15, respectively). After 295 days, weight gain, conception and kindling rates, pup and mother viability, ovarian macro- and micro-morphometric indices, release of leptin in response to the addition LH, and the release of progesterone, testosterone and leptin by isolated ovarian fragments were analyzed. Dietary turmeric failed to affect ovarian length and weight but did increase the number of primary follicles (E2: 32.5% greater than control group), as well as the diameter of primary (E1: +19.4%, E2: +21.1%), secondary (E2: +41.4%), and tertiary (E1: +97.1%, E2: +205.1%) follicles. Turmeric also increased the number of liveborn (E1: +21.0%) and weaned (E1: +25.0%) pups and decreased the number of stillborn pups (E2: −87.5%) but did not affect weight gain, conception, or kindling rate. Furthermore, dietary turmeric decreased doe mortality during the first reproductive cycle (13.3% in control; 0% in E1; and 6.7% in E2) but not during the second cycle. In vitro, the ovaries of the turmeric-treated rabbits released more progesterone (E1: +85.7%, E2: +90.0%) and less testosterone (E2: −87.0%) and leptin (E2: −29.0%) than the ovaries of control rabbits. Moreover, LH decreased the leptin output of control rabbits but increased that of experimental rabbits. Therefore, it is likely that dietary turmeric improves pup viability and that it could promote rabbit fecundity by either (1) promoting the production of primary ovarian follicles or (2) stimulating the growth of follicles at all stages of folliculogenesis.     

Di (2-ethylhexyl) Phthalate Exposure Impairs Growth of Antral Follicle in Mice

Di (2-ethylhexyl) phthalate (DEHP) is a widely used plastic additive. As an environmental endocrine disruptor, it has been shown to be harmful to the mammalian reproductive system. Previous studies indicated that DEHP inhibited the development of mouse ovarian follicles. However, the mechanisms by which DEHP affects ovarian antral follicle development during the pre-puberty stage are poorly understand. Thus, we investigated the effects of direct DEHP exposure on antral follicle growth in pre-pubescent mice by use of intraperitoneal injection. Our results demonstrated that the percentage of large antral follicles was significantly reduced when mice were exposed to 20 or 40 μg/kg DEHP every 5 days from postnatal day 0 (0 dpp) to 15 dpp. In 20 dpp, we performed microarray of these ovaries. The microarray results indicated that mRNA levels of apoptosis related genes were increased. The mRNA levels of the apoptosis and cell proliferation (negative) related genes Apoe, Agt, Glo1 and Grina were increased after DEHP exposure. DEHP induced the differential gene expression of Hsp90ab1, Rhoa, Grina and Xdh which may play an important role in this process. In addition, TUNEL staining and immunofluorescence showed that DEHP exposure significantly increased the number of TUNEL, Caspase3 and γH2AX positive ovarian somatic cells within the mouse ovaries. Flow cytometer analyses of redox-sensitive probes showed that DEHP caused the accumulation of reactive oxygen species. Moreover, the mRNA expression of ovarian somatic cell antioxidative enzymes was down-regulated both in vivo and in vitro. In conclusion, our data here demonstrated that DEHP exposure induced oxidative stress and ovarian somatic cell apoptosis, and thus may impact antral follicle enlargement during the pre-pubertal stage in mice.     

Androgen receptor in early apoptotic follicles in the porcine ovary at pregnancy

Localization of androgen receptor (AR) was investigated in ovarian follicles developing and undergoing atresia during pregnancy in the pig. Immunohistochemical staining was conducted on ovarian antral follicles isolated on different days of gestation: 10, 18, 32, 50, 70, and 90. Paraffin sections were also subjected to in situ DNA labeling. TUNEL staining revealed the presence of positive follicles on all days of pregnancy but the amount of atretic follicles increased with time. However, even on day 90 of gestation many follicles were normal, with no signs of atresia. In atretic follicles, apoptotic cells were localized predominantly in the granulosa while theca was much less affected. Atretic follicles with many apoptotic cells were negative for AR. Nuclear immunostaining for AR was positive in follicles with limited amount of apoptotic cells. The same relationship was observed in ovarian follicles isolated at various days of pregnancy.     

Buserelin overcomes the effect of the corpus luteum on ovarian follicular development in postpartum cycling cows

Follicular development after treatment with a gonadotropin-releasing hormone agonist (buserelin) was compared in ovaries of postpartum cows bearing (CLO) or not bearing (NCLO) a corpus luteum (CL). In the first experiment, 16 cows on day 7 of the estrous cycle (day 0 of treatment) were treated either with saline or 8 μg of buserelin. Both ovaries were collected on day 3 or day 6 (n = 4 per group per day) and follicles over 1.57 mm in diameter were observed histologically. Compared with day 3 in the saline group, there was a greater decrease in the percentage of Class I total (1.57–3.67 mm; P < 0.08) and Class 1 atretic follicles (P < 0.04) but a greater increase in that of Class 2 total (3.68–8.57 mm; P < 0.06), Class 2 atretic (P < 0.04) and early atretic (P < 0.05) follicles on day 6 in the CLO than in the NCLO. In the buserelin group however, all follicular responses (except for Classes 1 and 2 nonatretic follicles, P < 0.08) were similar (P > 0.1) between CLO and NCLO within 3 days after treatment. In the second experiment, follicular responses in CLO and NCLO were compared by daily ultrasonography in cows that had (n = 6) or did not have (n = 4) a buserelin-induced ovulation. After buserelin treatment, the numbers of medium (5–10 mm) and large (over 10 mm) follicles were not different (P > 0.1) between the CLO and the NCLO whether ovulation occurred or not. Results indicate that treatment with buserelin overcame most of the local effects of the CL on the growth and atresia of ovarian follicles in postpartum cycling cows within a 6 day period and this occurred whether ovulation was induced or not.     

Unilaminar follicular cells transiently express galectin-3 during ovarian folliculogenesis in pigs

The localization of galectin-3, a β-galactoside-binding animal lectin, was immunohistochemically studied in the ovaries of pigs to determine its expression in ovarian folliculogenesis. Various stages of ovarian follicles were identified in the ovaries of adult pigs. Galectin-3 was immunostained in the squamous follicular cells surrounding oocytes in primordial follicles and in the unilaminar granulosa cells of primary follicles, but not in oocytes of multilaminar follicles (including primary, secondary, and tertiary Graafian follicles). As in adult ovaries, galectin-3 immunoreactivity was prominent in the unilaminar follicles in neonatal ovaries. Galectin-3 was also immunolocalized in the luteal cells in the corpus luteum and granulosa cells of atretic follicles as well as in interstitial macrophages in porcine ovaries. Collectively, these results suggest that galectin-3 is transiently expressed in follicular cells in the unilaminar ovarian follicles (primordial and primary) but not in multilaminar ovarian follicles (primary to tertiary), implying that galectin-3 is embryologically involved in ovum generation.     

Influence of vitrification techniques and solutions on the morphology and survival of preantral follicles after in vitro culture of caprine ovarian tissue

The objective was to compare the efficiency of various vitrification techniques and solutions for preserving morphology and viability of preantral caprine follicles enclosed in ovarian tissue. Fragments of ovarian cortex were cryopreserved by conventional vitrification (CV) in French straws, vitrification in macrotubes (MTV), or solid-surface vitrification (SSV). Six solutions containing 6 M ethylene glycol, with or without sucrose (SUC; 0.25 or 0.50 M) and/or 10% fetal calf serum (FCS) were tested (Experiment I). After 1 wk, samples were warmed and preantral follicles were examined histologically. To evaluate follicular viability (Experiment II), ovarian fragments were vitrified with the three techniques listed above, in a solution containing 0.25 M SUC and 10% FCS. After warming, follicles were assessed by the trypan blue dye exclusion test. In Experiment III, preantral follicles enclosed in ovarian tissue were vitrified using the protocol which yielded the highest percentage of viable preantral follicles (SSV with 0.25 M SUC and 10% SFB). After warming, the preantral follicles enclosed in ovarian tissue were cultured in vitro and then, were analyzed by histology and fluorescence microscopy (calcein-AM and ethidium homodimer-1). Every vitrification protocol significantly reduced the percentages of morphologically normal follicles relative to the control (88.0%); however, the addition of 0.25 M SUC and 10% FCS to the vitrification solution improved preservation of follicular morphology (67.4, 67.4, and 72.0% for CV, MTV, and SSV, respectively). Although follicular viability after SSV (80.7%) did not differ from that in fresh (non-vitrified) ovarian tissues (88.0%), after in vitro culture, percentages of viable follicles were significantly reduced (70.0%). Percentages of morphologically normal follicles after in vitro culture of vitrified ovarian tissue were similar (76.0%) to those in ovarian cortex fragments cultured without previous vitrification (83.2%). In conclusion, SSV using a solution containing 0.25 M SUC and 10% FCS, was the most efficient method for vitrifying caprine ovarian tissue.     

Ovarian Toxicity in Female Rats after Oral Administration of Melamine or Melamine and Cyanuric Acid

Although the toxicity of melamine to the kidneys and testes is well known, few studies have investigated the effects of melamine on female reproductive organs. Therefore, this study explores the effects of oral administration melamine or melamine and cyanuric acid for 28 days on the ovaries of female rats. Rats that were exposed to the mixture exhibited reduced ovarian and uterine weights, a shorter estrous cycle, and reduced serum estrogen and progesterone levels compared to rats that were exposed to melamine and control rats. Furthermore, morphological analysis revealed pathological changes in the ovaries of rats exposed to melamine or the mixture, such as more atretic follicles and necrosis of oocytes and granulosa cells. TUNEL staining revealed that the exposed groups had a higher proportion of TUNEL-positive granulosa cells than the control group, and the mRNA expressions of SOD1, GPX1, GPX2, P450scc, 17β-HSD I, and 17β-HSD II were reduced in the exposure groups compared with the control group. These results indicated that exposure to melamine alone or to the melamine-cyanuric acid mixture could damage the ovaries in rats.     

Prevention of ovarian damage induced by cyclophosphamide in adult female mice by hormonal manipulations

Doses of 10 or 20 mg cyclophosphamide/kg body weight were administered daily to mice for up to 20 days. This caused significant reductions in the incidence of prenatal (developing) follicles and significant increases in atretic (degenerating) follicles within the ovaries. Attempts to prevent cyclophosphamide-induced damage by simultaneous treatment with oestrogen alone, oestrogen plus progesterone, or danazol (a synthetic androgen) demonstrated that danazol effectively prevented the ovarian damage. The efficacy of danazol was considered to be due to its ability to inhibit LH/FSH secretion and, indirectly, the development of new ovarian follicles.     

Effects of diets containing gossypol on ovarian histology, function and fertility in prepubertal beef heifers

Forty-five crossbred beef heifers (weight = 268.3 +/- 5.7 kg) were used to determine the effects of dietary gossypol on ovarian morphology, erythrocyte fragility and fertility. Heifers were randomly assigned to 1 of 3 isonitrogenous dietary treatments. The diet consisted of rice mill feed and milo supplemented with soybean meal (n = 13; control), cottonseed meal (n = 16; low supplementation) which supplied 6.1 g free gossypol animal(-1) day(-1), or whole cottonseed (n = 16; high supplementation) which supplied 13.7 g free gossypol animal(-1) day(-1). The heifers were group-fed each diet for 64 days and were maintained on similar but separate fescue pastures overseeded with wheat. After 64 days, 4 heifers from each diet were confined and fed their respective diets. On Day 10 following estrus, each animal was unilaterally ovariectomized, and the ovary containing the corpus luteum was removed. The remaining ovary was removed 6 to 12 hours after detection of estrus in the next cycle. Erythrocyte fragility increased (P < 0.02) in heifers receiving gossypol compared with that of the controls. Cyclicity in the heifers was 81.3, 68.8 and 38.4% for high, low and control diets, respectively, at the end of the 64-day treatment period. First service conception rate, as determined by palpation per rectum, was similar among treatments (58.3, 33.3, 33.3% for high, low and control groups, respectively). Weight gain increased (P < 0.03) in control heifers compared with that of heifers receiving gossypol. Gross ovarian morphology and histology were similar for all heifers. Although gossypol produced mild toxicosis in heifers, no adverse reproductive effects could be detected from gossypol intake.     

Studies on morphological features of foetal and adult ovaries in Kano brown goats

In this work we studied the structures of 51 foetal and 14 adult ovaries obtained from slaughtered Kano brown does in Nsukka abattoir. The ages of the adult does were determined by dentition and foetuses by crown rump length method. The foetal and adult ovaries were divided into five different groups using specific age intervals as Gestation day (GD) 50–65, 66–95, 96–125 and 126–145 and adults. For histological studies the ovaries were fixed, processed and routinely stained with H&E. The ovarian follicles were classified into 5 types according to granulosa cell layers surrounding the oocytes. The number of ovarian follicles per microscopic field, number of granulosa cells surrounding type 1 and 1A follicles and diameter of the ovarian follicles were determined for each group at 400× magnification. Grossly the foetal ovaries were like pin head, oval in shape, uniformly smooth and creamy in colour. The adult ovaries had follicles with different sizes. The adult mean ovarian weights were significantly higher (P < 0.01) than those of the foetuses. Microscopically, the GD 50–65 ovaries had no distinct cortex and medulla. Oogonia were numerous among other stromal cells toward the periphery of the ovary. By GD 66–95 the ovaries contained types 1, 1a, 2 and 3 follicles. GD 96–125 ovaries contained type 4 follicles with early antrum formation and those of GD 126–145 comprised type 5 among other follicles. The adult ovaries comprised all the ovarian follicle types. The number of type 1 follicles increased significantly (P < 0.01) with foetal age. It was least in the adults. The diameter of adult follicles was significantly higher (P < 0.01) than those of the foetuses. This result provides baseline information on the morphological development of ovaries in Kano brown goats.