• Journal of Embryo Transfer
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• v.5 no.1
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• pp.1-20
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• 1990

Follicular atresia is a universal and characteristic phenomenon of both non-mammalian and mammalian vertebrates. Generally it is estimated that greater than 99% of follicles become atretic in higher domestic animals and human. The number of selected follicles developing to the preovulatory stage are thus fewer. Follicles can become atretic at any stage of development. The previous studies emphasized on descriptive and retrospect aspects of a limited population of the fully grown preovulatory follicle. The main efforts in ovarian physilogical researches are focused on follicular development culminating in ovulation but recent advances have resulted in a better understanding of atresia. Nowadays, recent studies are concentrated on the induction of atresia in a selected population of follicles and of the associated cellular, endocrine, biochemical and molecular changes. The factors initiating atresia and follicle selections are worthy of investigations. Another intriguing question is whether one can predict when a follicle will become atretic, i.e., what biochemical markers indicate that a follicle is destined for atresia. It is generally agreed that atretic process may vary even in antral follicles at different stages of their differentiations and among species. The dicisive factors are follicular responsiveness and the hormonal milieu. Some generalizations can be made on the basis of experimental induction of atresia. Alteration of the pattern of follicular steroid production is associated with the initiation stage of atretic process. Atresia appears to be a process unfolding gradually and affecting progressively in increasing number of functions and components of the follicle. The oocyte may be the latest to be afflicted in the atretic process. The high steroidogenic activity of atretic follicles lends support to the notion that atresia is not necessarily a degenerative process and that atretic follicles may play an essential role in ovarian physiology. The simultaneous occurence of growth and atretic processes may render the search for regulatory mechanisms involved in atresia difficult extremely. The questions such as how follicles are selected to undergo ovulation rather than atresia or what the mechanism of atresia is remain unanswered. However, the factors regulating or modifying ovarian hormonal milieu for the initiation of follicular growth and maturation or of atresia are being elucidated.

• Biomedical Science Letters
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• v.12 no.2
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• pp.105-112
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• 2006

This study was undertaken to investigate the morphological changes between normal and atretic follicle after gamma irradiation and treatment of follicle stimulating hormone (FSH). The ovaries of each group of treated immature mice were prepared the paraffin sections after 0, 6, 12, and 24 hours (hrs) of those treatment. Hematoxylin-eosin (HE) stain, reticulin stain, and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) immunohistochemical stain were performed on the each paraffin sections. As the results of HE staining, the condensed nuclei of oocytes were observed in the atretic primordial follicles, on the other hand the condensations of granulosa cell nuclei were prominent in the atretic primary, preantral, and antral follicles. Only the granulosa cells of atretic follicle were stained specifically with TUNEL staining but not stained in the theca cells, which suggested granulosa cells degenerated through apoptosis. In the reticulin staining, the basement membranes of atretic follicle which was stained weakly showed irregular structure and detachment from the follicles. The ratio of normal to atretic follicle in control and FSH treated group was about 33% but this ratio increased rapidly over 90% in the 6, 12, and 24 hrs group after the irradiation. It could be suggested that the gamma irradiation is the useful tool far the induction of follicle atresia and immunohistochemical staining methods are essential in the study of follicle atresia.

• Korean Journal of Veterinary Research
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• v.37 no.1
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• pp.79-86
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• 1997

This study was designed to investigate the effects of superovulation on the growing and mature follicles following gonadotrophin treatments in mature rat by immunohistochemical methods. Eighteen mature rats (Sprague-Duwely, 190~230gm) were randomly alloted into 3 groups. One group was control group, another FSH-treated group was injected intramuscularly with 0.5 units of follicular stimulating hormone(FSH) / rat, and third PMS and HCG-treated group was injected intramuscularly with 20~25IU of pregnant mare serum(PMS) / rat and then at the 48 hrs later, with 20~25IU of human chorionic gonadotropin(HCG) / rat. Half the number of rats were administrated intraperitoneally with bromodeoxyuridine(Brdur, 0.2mg/gm BW once) at 2 hours before exanguination and the remainder of rats were sacrified without Brdur administration. The investigation by immunohistochemical methods using paraffin sections of ovaries was performed by using anti-Brdur antibody and PCNA(proliferating cell nuclear antigen) antibody for labeling proliferating cells in follicles. In immunohistochemical findings, follicles squeezed by peripheral corpus luteum or follicles large follicles with loosly and irregularly distributed granulosa cells and although with compacted granulosa cells, middle follicles with dilated round or oval follicular antrum were confirmed as atretic follicles. The proportions of atretic follicles in control group were 29.8%, 21.7% and 14.2% respectivley at large, middle and small follicles and mean proportions of these all 3 grade follicles were 26.7%. The proportions of atretic follicles in FSH-treated group were 35.4%, 24.9% and 10.4% respectively at large, middle and small follicles and mean proportions of these all 3 grade follicles were 28.1%. The proportions of atretic follicles in PMS and HCG-treated group were 44.7%, 24.0% and 12.7% respectively at large, middle and small follicles, and mean proportions of these all 3 grade follicles were 29.7%. The above findings reveal that the group with higher proportion of atretic follicles were ordered as large, middle and small follicles in size, and these proportions were increased in hormone treated two groups with more number of more growing and mature follicles when compared with control group.

• Korean Journal of Veterinary Research
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• v.17 no.2
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• pp.41-49
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• 1977

The present study was underve the histochemical nature of various follicles and interstitial tissues in the ovaries of Korean native goats and cattle as well as the histochemical changes of those in the ovaries of Korean native goats treated with dexamethasone. Much more lipid granules appeared in the granulosa and theca cells of atretic follicles compared with normal follicles in these ruminant ovaries. In the ovaries of Korean native goats the interstitial tissue derived from the theca interna of atretic follicles appeared the form of patches of cells and the interstitial tissue derived from stromal cells appeared the form of diffuse, obscure bounds. In the ovaries of Korean native cattle the interstitial tissue derived from theca interna of atretic follicles showed sparsely scattered form of pathes of cells. The histochemical components were described on the basis of lipids in the granulosa and theca cells of normal follicles, atretic follicles and interstitial tissue. In the ovaries of Korean natve goats treated with dexamethasone, the granulosa and theca cells of atretic foillicle contained plenty lipid granules that were increased in size and number, however, lipid granules were markedly decreased in the interstitial tissue.

• Nuclear Engineering and Technology
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• v.33 no.3
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• pp.255-260
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• 2001

In mammals, most of the follicles can not be ovulated, and instead, are degenerated throughout the entire reproductive period. However, the precise mechanism of follicle atresia is unknown. Three weeks old female mice (ICR strain) were ${\gamma}$-irradiated with a dose of LD$^{50}$ . Before irradiation (day 0) and at day 1, 2, and 3 after irradiation, the normal and atretic preantral and antral follicles of the left ovaries were morphologically observed. Atretic follicles at 2 days after irradiation had numerous cell debris, apoptotic cells and bodies, and polymorphonuclear leukocytes in the antral cavity. In severely atretic follicles, numerous polymorphonuclear leukocytes infiltrated into the follicle. The frequencies of atretic antral (58.0 $\pm$8.6) and preantral follicles (27.3$\pm$11.2) induced by ${\gamma}$-radiation increased to 94.0$\pm$3.4 and 86.9$\pm$7.6, respectively at 2 days after irradiation (p<0.05). The number of follicles with one or more neutrophils in the largest cross sections at 2 and 3 days after irradiation significantly increased (p<0.05). It can be concluded that ${\gamma}$-radiation triggers the recruitment of neutrophils into the follicles during degeneration. The ovarian follicles can make a role of informative biological end-point useful for disaster-prevention.

• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.555-561
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• 2003

Incidence of estrum or abortions in pregnant cows may be affected by large follicles developed together with corpus luteum in pair ovaries of pregnant cows. But the follicles of pregnant phase were not assessed about histological findings. Determination of the healthy and atretic follicles by presence of proliferative cells or apoptotic cells and histological compositions of follicles would be used as important data on measurements of ovarian functions. This study was focussed mainly to investigate macroscopical, histological and immunohistochemical findings of ovarian follicles of pregnant Korean native cows and dairy cows (Holstein). In immunohistochemical methods, assessments of proliferative cells using PCNA antibody and apoptotic cells using TUNEL methods were performed. The follicles were observed on all 24 pregnant cows (17 Korean native cows and 7 Holstein cows). Follicles of greater than 10 mm in daimeter were developed in 37.5% (9/24 heads) of these pregnant cows. largest follicles from in these cows were $16.0{\times}15.0mm$ in diameter in a Korean native cow(l20 days of gestation), $13.4{\times}10.1mm$ in a Korean native cow(50 days of gestation), $12.9{\times}11.5mm$ in a Holstein cow (120 days of gestation). 40.5% among all follicles having diameter of greater than 1.0 mm in pregnant cows were assessed as atretic follicles and in addition, healthy follicles also showed less in number and smaller in size and thinner in wall layer compared with those of cyclic phase ovaries. In immunohistochemical findings, also proliferative positive cells and apoptotic positive cells on the granulosa cell layers in the healthy follicles of pregnant cows appeared less than on those of cyclic follicles. So these follicles were assessed as weakly active follicles. In large follicles, above positive cells were not nearly appeared but granulosa cell debris were more appeared among the granulosa cells. So these large follicles were assessed as inactvie or atretic follicles. The above findings suggest that small follicles of pregnant phase were weakly active or atretic and large follicles were inactive or atretic.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1647-1651
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• 2004

The follicles (1.8 to 7.8 mm in diameter) were recovered from the ovaries in marketed pigs and the number of granulosa cells, the diameter of oocytes obtained from different development stages of the follicles and follicular fluid levels were determined. Correlations between size measurements and cell counts as well as the diameter of antral follicles and oocytes were also investigated. The results indicated that, while expanding in size, follicle numbers decreased with a greater atretic proportion. Granulosa cells increased in numbers continuously and remained unchanged beyond the size of 200 ${mm}^3$ in non-atretic follicles, whereas a sudden drop of granulosa counts was observed in atretic follicles. Follicular fluid, on the other hand, linearly increased its volume with follicle size and differed little between those of non-atretic and atretic follicles. Diameters of oocytes in non-atretic follicles increased to its maximum when follicles expanded to 150 ${mm}^3$ and maintained its size during later follicular expansion. It is concluded that, for in vitro culture, the optimal size of porcine follicle should be between 150 to 180 ${mm}^3$if they are collected from pre-pubertal gilts of marketing size slaughtered in an abattoir.

• Clinical and Experimental Reproductive Medicine
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• v.13 no.1
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• pp.29-38
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• 1986

In order to study the mechanism of follicular atresia, follicles were classified into the normal groups and the atretic ones, according to the criteria with or without corpus luteum, size of follicles, vascularization, status of granulose cells and the hypertrophy of theca layers in the porcine ovary. To estimate the binding capacity of human chorionic gonadotropin (hCG) receptor on the granulosa cells during atresia, hCG were iodinated by the chloramine-T method and then purified through the column chromatography. The concentration" of hCG receptor in each group were measured by the hCG receptor binding assay. Binding capacity in large normal follicles were 1.16%, but atretic ones were 0.45%. But in medium and small follicles (below 6mm in diameter), the binding capacity in normal follicles were 0.09%, but atretic ones were 0.05%, which was lower than those of large follicles. The present ( ) that the concentrations of hCG receptors on granulosa cells is decreased when the follicles become atretic and be used as a sort of creteria for the identification of follicles atresia.

• Korean Journal of Animal Reproduction
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• v.21 no.3
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• pp.265-274
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• 1997

The purpose of this study was attempted to investigate the a, pp.arences of healthy or artretic follicles in ovaries following repeats of pregnant mare serum gonadotropin(PMSG) treatments for superovulation in nulliparous rats. Thirty two rats(Sprague-Dawely, about 200-250 gm) were randomized into 4 groups. Control group rats were sacrified at estrus phase confirmed by vaginal smear. PMSG-treated group 1 rats, PMSG-treated group 2 rats and PMSG-treated group 3 rats were sacrified at 48 hrs after injection once with PMSG 25 IU, after 2 repeated injection by a week interval, and 3 repeated injection, respectively. The ovaires of rats were removed and then sections by paraffin embedding were stained with H-E or immunohistochemical staining using proliferating cell nuclear antigen monoclonal antibody (PCNA m Ab) and apoptotic kit. The criteria of follicle classification was based as small follicles with preantral follicles with 2~4 layers of granulosa cells surrounding the oocyte, as secondary follicles with more than 5 layers of granulosa cells and early signs of antral cavity or with small clefts on either side of the oocytes, and as tirtiary follicles with a single medium sized antral cavity or large well-formed antral cavity, respectively. The proportions of atretic follicles from small and middle follicles in immunohistochemical staining using PCNA m Ab were 17.9% and 21.3% in control group, 15.5% and 23.5% in PMSG-treated group 1, 24.3% and 26.7% in PMSG-treated group 2, 18.1% and 30.2% in PMSG-treated group 3, respectively. Groups with atretic follicles of higher proportion were ordered as PMSG-treated group 3, PMSG-treated group 2, PMSG-treated group 1 and control group. The proportions of positive cells in small, middle and large follicles were 31.1%, 33.5% and 28.5% respectively. The follicles with positive cells of higher proportion were ordered middle, small and large follicles. In immunohischemical staining using apoptotic kits, small follicles in all 4 groups did not contain positive cells, and proportions of atretic follicles from middle and large follicles were 24.9, 30.7, 33.8 and 40.1% in control, PMSG-treated gruop 1, PMSG-treated group 2 and PMSG-treated group 3, respectively. These results suggested that repeats of PMSG treatment increased proportion of atretic follicles in ovaries, and middle follicles are more quickly developing than small or large follicles.

• The Korean Journal of Zoology
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• v.32 no.3
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• pp.281-289
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• 1989

The present study was disigned to determine the concentration of bioavailable steroid hormones in the atretic follicular fluid (FF). The concentradons of progesterone (P), testosterone (T), estradiol (E), androstenedione (A), and 5-$\alpha$ dihydrotestosterone (DIlT) were determined by the established methods of luminescent immunoassay (LIA) or radioimmunoassay (RIA). Concentrations of T, A and Diff in human FF from smail (< 6 mm). medium (8-15 mm), and large (> 15 mm) atretic follicles were significandy higher than those of normal ones (p < 0.01). However, the levels of T, A and DHT in smail atretic foflicle were significandy lower than those found in normal one. The concentrations of P in atretic FF from porcine small (< 3 mm), medium (4-6 mm), and large (> 7 mm) follicles were not different from that of normal ones. However, the concentration of E in atretic forncles of each group was significantly lower than that of normal group (p < 0.001 in each group). On the other hand, the percentages of bioavailable T (BI) in human FF were significandy (p <0.001) higher than those in normal groups. The BT in normal or atretic FF was more than 90 % of total T. The present result demonstrates that the bioavailable androgen, but not E levels in atretic follicles is higher than that of normal one, and that the atretic mechanism might be dependent on the ovarian forncle size in the developmental stage and on the animal model system. Moreover, the present study suggests that the steroids found in the FF are the bioavailable forms and the concentration of BT in FF could be used as one of the valuable criteria classifying the ovarian atretic follicle.