Journal of reproduction and fertility. Supplement (J Reprod Fertil Suppl )

Publisher: Society for Reproduction and Fertility


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    Reproduction (Cambridge, England)
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    Journal / Magazine / Newspaper

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Sperm preservation has become a routine procedure in dog breeding. In this study, the influence of prostatic fluid on sperm characteristics after preservation (either chilling or freezing) was investigated. The sperm-rich fractions of 20 ejaculates from five dogs were either extended without centrifugation or centrifuged and resuspended either directly in extender or in prostatic fluid before dilution with extender. Aliquots were processed for storage at 4 degrees C for 6 h or for freezing. Storage at 4 degrees C did not affect sperm motility, viability or acrosome integrity, irrespective of the dilution treatment. However, sperm motility and viability decreased significantly after freezing and thawing, particularly in the samples with additional prostatic fluid. In contrast, the acrosome morphology of viable spermatozoa was not affected by either the dilution method or by chilling or freezing and thawing. It is concluded that addition of prostatic fluid during semen processing adversely affects the motility and viability of frozen-thawed spermatozoa. However, prostatic fluid does not appear to affect the motility and viability of chilled spermatozoa or to alter acrosome integrity in either system of preservation.
    Journal of reproduction and fertility. Supplement 02/2001; 57:383-6.
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    ABSTRACT: This paper reviews some important links between nutrition and reproduction in a seasonal breeder, the mink (Mustela vison). The energetic costs of reproduction in mink are partly covered by mobilization of body fat reserves. A reduced food supply before the breeding season is detrimental to reproductive performance, and release of LH and ovulation may not occur in animals in extremely poor body condition. Nutritional flushing comprising a 2 week period of slightly restricted feeding, followed by ad libitum feeding for 4-5 days before the start of the mating season can influence reproductive performance positively. Reproductive endocrinology, ovulation and implantation rate, and early embryo development are affected by the modification of important metabolic signals including insulin, insulin-like growth factor I (IGF-I) and the thyroid hormones.
    Journal of reproduction and fertility. Supplement 02/2001; 57:97-101.
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    ABSTRACT: Highlighting the important aspects of canine reproductive physiology, this review documents developments made with in vitro culture of canine gametes, and indicates how these techniques can be further exploited. In vitro culture of gametes and embryos has been achieved in many mammalian species, allowing the development of reproductive technology. Despite numerous investigations in other species, only a small number have been performed in dogs. Further studies are required to establish the differences between canine reproductive physiology and that of other mammals. Ultimately, these studies may lead to the development of a gamete salvage technique incorporating oocyte, spermatozoa and embryo culture, and cryopreservation to allow genetically important material from Canidae to be saved. In dogs, the oocyte is ovulated when immature rather than mature, as in other species, and the survival rate of spermatozoa is greater within the female tract. By incorporating knowledge of canine reproductive physiology and work on in vitro culture in other mammals, some important achievements have been made. Sperm capacitation, induction of the acrosome reaction, maturation of canine oocytes and fertilization have all been achieved in vitro. Embryo culture has proven more difficult, with only two studies reporting success. Cryopreservation of spermatozoa has been perfected and is used routinely when transporting semen for artificial insemination. However, improvement in embryo culture techniques and development of oocyte and embryo freezing are required. This work in the domestic model may lead to development of a gamete-banking programme to safeguard the future of endangered canine species.
    Journal of reproduction and fertility. Supplement 02/2001; 57:111-25.
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    ABSTRACT: The aim of this study was to establish new methods for controlling reproduction in bears. Anti-progestins were used to interrupt pregnancies. In two consecutive years, the anti-progestin J956 was administered to 11 female bears (nine Ursus arctos, one Ursus tibethanus, one Tremarctos ornatus) living in zoos. The anti-progestin J956 was given orally (n = 4) or parenterally (n = 12). The anti-progestin was administered alone or in combination with ethinyloestradiol, and before or after embryo implantation. The effects of anti-progestin treatment were determined using ultrasonographic examination of the urogenital tract and by monitoring progesterone concentrations in the blood and faeces. Oral administration of anti-progestin was not successful (successful in 0 of 4); however, in contrast, none of the parenteral treated animals remained pregnant (successful in 12 of 12). Parenteral treatment with J956, with or without ethinyloestradiol, was effective in disrupting pregnancy before implantation (successful in 6 of 6) and after implantation (successful in 6 of 6), but administration one month after implantation (n = 2) resulted in incomplete resorption of the fetuses. In conclusion, the administration of anti-progestins may be a useful method for preventing embryo implantation in captive bears.
    Journal of reproduction and fertility. Supplement 02/2001; 57:249-54.
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    ABSTRACT: Our understanding of molecular mechanisms of fertilization in mammals has lagged behind the rapid development of reproductive technology over the last decade. Significant advances in knowledge have resulted mainly from studies in laboratory animals in vitro. However, this situation has changed in the last few years as targeted mutagenesis in mice has provided important new information about genes and proteins involved in basic aspects of sperm-egg interactions in vivo. In this brief review the current knowledge about the generic aspects of mammalian fertilization is summarized, together with particular features of reproductive physiology related to cats and dogs.
    Journal of reproduction and fertility. Supplement 02/2001; 57:105-10.
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    ABSTRACT: Taurine and hypotaurine have been found in spermatozoa and seminal plasma of numerous species and are known to have beneficial effects on sperm characteristics in mammals. Taurine is considered an essential dietary constituent in cats. Dietary deficiency has been associated with a range of serious clinical disorders. Quantification of taurine and hypotaurine in the genital tracts of male cats has not been reported. In this study, the concentrations of taurine and its precursors were measured in serum, spermatozoa, epididymal fluid and seminal plasma from cats. The concentrations of taurine measured in serum samples confirmed that the cats were not deficient in taurine. Significant amounts of taurine and hypotaurine were found in spermatozoa, seminal plasma and epididymal flushing fluid. Hypotaurine was not detected in serum samples. These results indicate that hypotaurine may be synthesized in cat testes or epididymides. Cysteamine was not detected in any of the samples.
    Journal of reproduction and fertility. Supplement 02/2001; 57:93-5.
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    ABSTRACT: Prepubertal gonadectomy, often referred to as early-age neutering, has increased in popularity in the United States. The procedure is often used at animal care and control facilities, where puppies and kittens are neutered as early as 7 weeks of age or before adoption. Although the anaesthetic and surgical procedures appear to be safe, studies continue to evaluate the long-term effects on health and behaviour. Early-age neutering is one technique that is used to combat pet overpopulation, a problem whereby millions of unwanted healthy dogs and cats are euthanased each year. Although neutering animals is helpful in controlling pet overpopulation, other factors must be considered. In addition, many animals are relinquished to shelters when they show inappropriate behaviours, because owners and veterinarians are unable to modify animal behaviour. This review discusses early-age neutering in the United States, and includes the review of scientific studies that have evaluated this procedure in puppies and kittens. Early-age neutering does not stunt growth in dogs or cats (a once-held belief), but may alter metabolic rates in cats. The anaesthetic and surgical procedures are apparently safe for young puppies and kittens; morbidity is lower and recovery is faster than in adult animals. To date, adverse side effects are apparently no greater in animals neutered at early ages (7 weeks) than in those neutered at the conventional age (7 months).
    Journal of reproduction and fertility. Supplement 02/2001; 57:223-32.
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    ABSTRACT: Our laboratory has experienced four phases in understanding how the reproductive sciences contribute to genuine conservation of biodiversity. The first is the 'quick fix phase' in which the erroneous assumption is made that extant knowledge and techniques are readily adaptable to an unstudied wild animal to produce offspring rapidly. The second is the 'species-specificity phase' in which it is recognized that every species has evolved unique reproductive mechanisms that must be mastered before propagation can be enhanced. The third is the 'applicability phase' in which one grasps that all the new knowledge and technology are of minimal relevance without the cooperation of wildlife managers. The final phase is 'integration', the realization that reproduction is only one component in an abundantly complex conservation puzzle that requires interweaving many scientific disciplines with elaborate biopolitical, economic and habitat variables. These phases are illustrated using 20 years of experience with wildlife species, including the cheetah, black-footed ferret and giant panda. We conclude that the foremost value of the reproductive sciences for conserving endangered species is the discipline's powerful laboratory tools for understanding species-specific reproductive mechanisms. Such scholarly information, when applied holistically, can be used to improve management by natural or, occasionally, assisted breeding. Genuine conservation is achieved only when the reproductive knowledge and technologies are integrated into multidisciplinary programmes that preserve species integrity ex situ and preferably in situ.
    Journal of reproduction and fertility. Supplement 02/2001; 57:295-307.
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    ABSTRACT: The present study describes the use of a zona pellucida binding assay for the evaluation of canine spermatozoa. A zona pellucida binding assay is a sperm evaluation test that is practical to perform and provides potentially useful information on the damage caused to spermatozoa by new methods of sperm storage. The addition of the detergent Equex STM paste to the cryopreservation extender has a positive effect on the zona pellucida binding capacity of cryopreserved spermatozoa. A large number of sperm-oocyte complexes need to be evaluated because of the variability in sperm binding capacity among oocytes. However, this does not constitute a major problem as canine oocytes can be stored before use in a zona pellucida binding assay and sperm-oocyte complexes can be fixed and stored until evaluation.
    Journal of reproduction and fertility. Supplement 02/2001; 57:137-40.
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    ABSTRACT: Transrectal ultrasonography, electroejaculation and cryopreservation of spermatozoa were applied to the African wild dog (Lycaon pictus) to establish non-invasive protocols for assessing the reproductive health of one of the most endangered African canids. Transrectal ultrasonography was performed on immobilized male (n = 2) and female (n = 5) captive wild dogs. The testes and epididymides of the male dogs were imaged transcutaneously, followed by electrostimulation and cryopreservation of spermatozoa. The sonomorphology of the female and male urogenital tracts was characterized. In females, the vagina, cervix, non-pregnant uterus and ovary were imaged and the reproductive health of each female was evaluated. The sonographic assessment helped to identify one pyometra and extensive abdominal fat deposits in two other individuals in which pyometra had been suspected. Images of the adrenal glands showed differences in size among individuals of the same breeding group. Whether these differences were related to the dominance hierarchy remains to be determined. In males, visualization of the prostate gland, testis and epididymis indicated sexual maturity. Three ejaculatory fractions (1.0, 1.5 and 0.5 ml, with 50, 95 and 95% motility, respectively; 1.125 x 10(8) spermatozoa per ejaculate) were collected from one male. The motility of each of these fractions after thawing was 0, 30 and 40%, respectively. Electrostimulation of the second male, in which a cystic structure in a testis had been identified by sonography, resulted in an aspermic ejaculate (0.5 and 1.0 ml). These technologies provided basic data on reproduction in female and male African wild dogs and were an efficient way to evaluate reproductive health.
    Journal of reproduction and fertility. Supplement 02/2001; 57:315-21.
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    ABSTRACT: The aim of this study was to evaluate the possibility of inducing fertile oestrus in queens by administering hCG in combination with Ca(2+)-naloxone. It is well established that an increase in endogenous opioids leads to a decrease in LH. The administration of naloxone, an opioid antagonist, inhibits endogenous opioidergic tone and induces the onset of pro-oestrus. The opioidergic block is related to the increase in binding of beta-endorphins to specific receptors, which determines calcium channel blockage. Pretreatment with hCG results in a rapid increase in the number of LH receptors and Ca(2+)-naloxone induces G protein activity. Twenty-one anoestrous queens were divided into four groups: (i) group 1, nine queens were treated with a single s.c. injection of hCG (1000 iu) and daily for 4 days with 0.1 ml kg-1 body weight i.m. of a solution containing 0.4 mg naloxone ml-1 dissolved in 20% calcium gluconate; (ii) group 2, four animals were treated with a single s.c. injection of hCG (1000 iu); (iii) group 3, four queens were treated with Ca(2+)-naloxone (0.1 ml body weight kg-1 i.m.) daily for 4 days; and (iv) group 4, four queens received no treatment (controls). Queens were monitored using vaginal cytology and blood progesterone concentrations, and pregnancy was detected using ultrasonography. In groups 2, 3 and 4 clinical signs of oestrus were not observed. In group 1, 88.8% of treated queens were mated (8 of 9) and ovulated on the basis of an increase in progesterone, and 75% (6 of 8) of these queens became pregnant. In conclusion, pretreatment with hCG increased the number of LH receptors and Ca(2+)-naloxone antagonized the hypothalamic GnRH opioid block thus inducing the pulsatility of LH leading to fertile oestrus in queens.
    Journal of reproduction and fertility. Supplement 02/2001; 57:335-7.
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    ABSTRACT: The aims of the present study were to develop a device for vaginal and transcervical catheterization in domestic cats, and to study cervical patency during the various stages of the oestrous cycle. Seventeen queens submitted for routine spaying were included in the study. A vaginal catheter was designed from a urinary catheter for dogs, to fit into the ventral vaginal fornix, and a 3.5 French tomcat catheter was used as an inner transcervical catheter. Cervical patency was studied by infusing 0.5 ml Urografin into the cranial vagina and taking X-rays of the queens after 5 min. The Urografin did not enter the uterus, even in the oestrous queens. Transcervical catheterization was then attempted. The correct placement of the intrauterine catheter was confirmed by injecting green food colour mixed with penicillin G and observing the presence of stain in the uterine horns during surgery. Catheterization was successful in 13 of 17 queens: six of nine in interoestrus, three of three in oestrus, one of two in metoestrus and three of three in the postpartum period. Transcervical catheterization is a non-invasive technique that is likely to improve the success rate of assisted feline reproduction, and is potentially a useful non-surgical technique for diagnosis and therapy of uterine diseases.
    Journal of reproduction and fertility. Supplement 02/2001; 57:353-6.
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    ABSTRACT: The aim of this study was to determine whether the canine endometrium could be examined by hysteroscopy. Eight German shepherd bitches were used. Two bitches were in dioestrus, five were in anoestrus and one was about 8 weeks post partum. The uterus was exposed through a ventral celiotomy. A 3 mm straight laparoscope or a 4 mm laparoscope with a 30 degrees angle, and a catheter for inflation of the uterus were used. After hysteroscopy the bitches were spayed and the uterus of each bitch was examined macroscopically and histologically. Endometrium and uterotubal junctions were visible in all bitches. The cervix and caudal uterine body could not be visualized in three bitches as two bitches had uterine discharge and air escaped through the cervix in the other bitch. In the post-partum bitch, dark-brown sites of implantation were observed. Four bitches (aged 9, 22, 25 and 31 months) had endometrial cysts (0.5-2.0 mm in diameter). Hysteroscopy caused petechiae and ecchymosis in the endometrium of four bitches. Traumatization of the endometrium affected only the epithelium and the most superficial part of the lamina propria. In conclusion, hysteroscopy appears to be a very sensitive tool for evaluation of the canine endometrium. Further research is necessary to determine the effects of hysteroscopy on subsequent fertility.
    Journal of reproduction and fertility. Supplement 02/2001; 57:415-7.
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    ABSTRACT: The aims of the present study were: (i) to validate the accuracy of flow cytometry for assessment of viability and acrosomal status of canine spermatozoa; and (ii) to evaluate the cryopreservation protocols currently used for dog spermatozoa using flow cytometry. Data obtained by flow cytometry analysis of fresh dog spermatozoa stained with carboxyfluorescein diacetate (CFDA) and propidium iodide, or with fluorescein isothiocyanate (FITC)-conjugated Pisum sativum agglutinin (PSA) and propidium iodide, were compared with those obtained by microscopic evaluation. The results demonstrated that flow cytometry is a precise method for evaluating the viability and acrosomal status of fresh samples of dog semen. A new triple staining procedure, using carboxy-SNARF-1, propidium iodide and FITC-PSA, was developed and was an efficient method for evaluating the following aspects of cryopreservation protocols for dog spermatozoa: (i) addition of 0.5% (v/v) Equex STM paste to a Tris-egg yolk-based extender; (ii) dilution of the semen in one or two steps; (iii) freezing semen by placing 0.5 ml straws horizontally above liquid nitrogen in a styrofoam box or lowering them vertically into a liquid nitrogen tank; (iv) thawing semen at two different rates; (v) packaging semen at different sperm concentrations; and (vi) diluting semen at different rates after thawing. The highest sperm survival and longevity was obtained when Equex was present in the semen extender, the semen dilution was performed in two steps to obtain a concentration of 2.0 x 10(8) spermatozoa ml-1, the freezing was carried out using the styrofoam box, the straws were thawed at 70 degrees C for 8 s and the semen was diluted 1:4 after thawing.
    Journal of reproduction and fertility. Supplement 02/2001; 57:371-6.
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    ABSTRACT: The aim of this study was to validate a model in ovariectomized bitches for the study of uterine function. Mature bitches (n = 21) were ovariectomized and treated with oestradiol benzoate (0.6-4.8 micrograms kg-1, i.m. twice each day) and then with progestagen (megestrol acetate, 2 mg kg-1, p.o. once a day) and were necropsied at stages simulating pro-oestrus (n = 2), oestrus (n = 2) and dioestrus (n = 2). Other bitches received oestradiol benzoate and then megestrol acetate and were necropsied 3 weeks (midanoestrous group, n = 2) and 9 weeks (late anoestrous group, n = 2) after treatment. Untreated bitches (n = 1 per group) served as controls. The treatments induced oestrous behaviour, vulvar swelling, vulval discharge, vaginal smears, plasma oestradiol concentrations and uterine histology similar to that reported in intact bitches at each stage of the oestrous cycle. Marked endometrial degeneration and increased numbers of endometrial leucocytes were observed in the mid-anoestrous group. The endometrium was repaired in the late anoestrous group. A suture was placed in the lumen of the uterus of another six bitches at ovariectomy. Four of these bitches were treated with oestradiol benzoate and then megestrol acetate. Two bitches with a suture but not treated with hormones served as controls. In the hormone-treated bitches the suture resulted in cystic endometrial hyperplasia in two bitches and in cystic endometrial hyperplasia with pyometra in two bitches. The control bitches showed no cystic endometrial hyperplasia or pyometra. We have established in the ovariectomized bitch a model simulating the normal oestrous cycle that will facilitate studies of uterine function. This model will be used to study further the mechanisms of the endometrial degeneration and the pathogenesis of cystic endometrial hyperplasia.
    Journal of reproduction and fertility. Supplement 02/2001; 57:45-54.
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    ABSTRACT: The aim of this study was to investigate the secretion patterns of FSH: (i) during the canine oestrous cycle with particular attention to the luteal period; and (ii) during 24 h in male and female dogs. Plasma FSH concentrations were measured by a highly specific homologous canine immunoradiometrical (IRMA) assay using monoclonal antibodies specific for canine FSH. In the first study, FSH concentrations were measured daily from +/- 15 days before until 150 days after the LH surge in groups of pregnant (n = 5) and nonpregnant (n = 5) Beagle bitches. Day 0 of the cycle was the day of the preovulatory LH peak as measured by LH radioimmunoassay. In the second study, FSH concentrations were measured at 1 h intervals for 24 h in five bitches at day 120 after the LH surge and in five males. From day 35 to day 40 after the LH peak, FSH concentrations were higher in pregnant than in nonpregnant luteal phases. A significant and abrupt decrease in FSH concentrations was observed at about the time of parturition (day 65) and was followed by lower FSH concentrations during lactation compared with nonpregnant bitches. FSH concentrations in nonpregnant animals were fairly constant from the end of oestrus to mid-anoestrus. In both post-lactation and anoestrous bitches, plasma concentrations of FSH increased consistently as anoestrus progressed. No significant differences in the mean hour-to-hour patterns of FSH secretion were observed over 24 h and no differences were detected between male and female dogs. However, a clear pulsatile pattern of secretion was observed in all individuals, both males and females, with an apparent 4.8 h interval between peaks. The results of this study demonstrate major differences in FSH secretion between pregnant and nonpregnant bitches. This finding indicates that there are differences in the regulation of the hypothalamo-pituitary-ovarian axis during pregnancy, possibly related to changes in activity of the corpus luteum. The results of this study also demonstrate a pulsatile pattern of FSH secretion in both male and female bitches, with a 4.8 h interval between peaks, and confirms the progressive increase in plasma FSH concentrations observed during anoestrus.
    Journal of reproduction and fertility. Supplement 02/2001; 57:15-21.
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    ABSTRACT: The aim of this study was to identify and characterize populations of trophoblast cells in canine placenta during different stages of fetal development using lectin histochemistry. Dogs have endotheliochorial placentation and trophoblast cell invasion continues after chorioallantois villous penetration early in pregnancy, leading to formation of a labyrinth. Specialized subpopulations of cells differentiate, such as syncytial trophoblast that invades the maternal epithelium early in placentation and surrounds and forms intimate cuffs around maternal blood vessels. Marginal haematomata, which are lined by specialized phagocytic cytotrophoblast cells, form by mid-gestation. Invasive 'extravillous' cells advance into and remodel maternal endometrial tissues further. Placentas and attached uterine tissues were collected and sampled from six bitches at mid-gestation (days 31-33 of gestation) and 12 females in late gestation (day 42-term) for characterization of these tissues and identification of other populations of trophoblast cells. Uterine tissues from nonpregnant bitches were also collected at oestrus (n = 2) and during the luteal phase (n = 1). In histochemical studies, two of six biotinylated lectins that were tested stained cytotrophoblast and syncytial trophoblast cell populations differentially. Arachis hypogaea agglutinin (PNA) was specific for cytotrophoblasts in placental tissue lining villi and cytotrophoblastic cells with phagocytic or absorptive phenotypes in the necrotic zone at mid-gestation. In late gestation, cytotrophoblast cells with an absorptive phenotype at the interface between the labyrinth and lacunar glandular chambers were stained with PNA. Staining of other cells was minimal, with the exception of deep endometrial glands. Lectin binding using Maclura pomifera agglutinin (MPL) specifically stained the same cells as PNA and the population of invasive syncytial trophoblast cells remodelling maternal blood vessels and small maternal vessels at the materno-fetal interface, as well as trophoblast cells within necrotic zones at mid-gestation. Both lectins were positive for phagocytic cytotrophoblast cells lining the haematophagus organs. The results of this study demonstrate that lectin histochemistry is a useful tool for staining subpopulations of cytotrophoblast and syncytial trophoblast cells.
    Journal of reproduction and fertility. Supplement 02/2001; 57:199-206.
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    ABSTRACT: The application of zona pellucida proteins for contraception of wildlife and feral animals, including stray cats, has been promoted since it was demonstrated to be effective for free-roaming feral mares. Active immunization with zona pellucida proteins leads to either reversible or irreversible infertility. Therefore, knowledge of the timing and location of zona pellucida synthesis during oogenesis in cats is a key aspect of designing an immunocontraceptive for felids. Domestic cat ovaries obtained after ovariohysterectomy were used to produce a specific rabbit antibody against feline zonae pellucidae. Ultrathin sections (70 nm) of cat ovaries were treated with the anti-zona antibody followed by incubation with gold-labelled anti-rabbit IgG for ultrastructural investigation. The gold label was related to the ultrastructure of oocytes and granulosa cells. Cat follicles at different stages of development were examined. The antibody reacted very specifically with zona pellucida proteins in fully grown oocytes with a compact zona pellucida. In secondary follicles, gold labels were found on the zona pellucida and inside granulosa cells in the vicinity of oocytes. Primary follicles were labelled inside their cubic granulosa cells and on fragments of zona pellucida in the cleft between granulosa cells and the oocyte. Some primordial follicles were characterized by labelling of the granulosa cells. In conclusion, these results indicate that cat zona pellucida is produced exclusively by granulosa cells and not by oocytes. Synthesis of zona pellucida takes place at every stage of follicular development.
    Journal of reproduction and fertility. Supplement 02/2001; 57:23-9.

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