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1

Variation in the ovarian and plasma progesterone and estradiol levels of the domestic hen during a pause in laying

100%
Proszkowiec M., Rzasa J.
Folia Biologica
|
2001
|
vol. 49
|
issue 3-4
285-289
EN
Little is known about the physiological events occurring in the chicken ovary during a pause in laying, therefore the aim of the present study was to examine changes in sex steroid concentration in the follicle wall and blood plasma during cessation of egg laying. The experiment was performed on laying Isa Brown hens. Control hens were fed ad libitum whereas the experimental ones were subjected to a pause in laying by complete food deprivation for 5 days and water deprivation on 3 day followed by feeding every second day up to 9 day and then ad libitum. Blood samples were taken from the wing vein each day. The hens were decapitated on day 3, 6, 9, and 16. The ovary was isolated and the following follicles were dissected: white (1-2; 2-4; 4-6; 6-8 mm) and yellow preovulatory ones (F1-F3). Progesterone and estradiol were measured in the follicle wall and blood plasma by RIA methods. The hens stopped egg laying on day 4 and began egg restoration on day 14 of the experiment. Cessation of egg laying was preceded by a decrease in estradiol and progesterone levels in the ovary as well as in the blood plasma. The plasma level of these steroids began to increase 7 days before the start of egg restoration. Autopsy of the ovary showed that the atrophy of the chicken yellow preovulatory follicles during the pause in laying was accompanied by a significant increase in the total number of white follicles.
2

Serotonin content in the wall of preovulatory and postovulatory follicles of the domestic hen

100%
Paczoska-Eliasiewicz H., Rzasa J.
Folia Biologica
|
1995
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vol. 43
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issue 1-2
75-79
EN
Serotonin (5-HT) level in the 4 largest preovulatory (F4-F1) and 2 postovulatory follicles (POF1-POF2) was determined spectrofluorometrically.During the final, most rapid phase of follicular development, 5-HT content in the preovulatory follicles wall increase gradually, reaching the highest level 0.5 before ovulation.After ovulation 5-HT content in postovulatory follicles rapidly decreased.The results suggest that 5-HT is involved in ovarian functions like folicular development and ovulaton in the domestic hen.
3

Presence of histamine and mast cells in chicken oviduct

81%
Hrabia A., Rzasa J., Paczoska-Eliasiewicz H., Slomczynska M.
Folia Biologica
|
2001
|
vol. 49
|
issue 3-4
265-271
EN
The purpose of the present study was: (1) to demonstrate immunocytochemically the localization of histamine in the wall of four chicken oviductal parts, i. e. infundibulum, magnum, isthmus, and shell gland, (2) to identify the presence of mast cells in chicken oviduct, and (3) to determine histamine concentration in oviductal tissue by the spectrofluorometric method. Experiments were carried out on Isa Brown laying hens decapitated just after oviposition. The specific immuno-reactivity for histamine and the presence of mast cells were found in the wall of all the examined oviductal parts. The immuno-reactive histamine was localized in epithelium, tubular glands, connective tissue layer, circular and longitudinal muscles, and endothelium and muscles of blood vessels. The intensity of immuno-positive reaction was as follows: infundibulum > shell gland > magnum = isthmus and correlated with quantitatively determined histamine level and tissue density of mast cells. It is suggested that mast cells are the main source of histamine in the chicken oviduct.
4

Expression of alpha and beta estrogen receptors in the chicken ovary

81%
Hrabia A., Wilk M., Rzasa J.
Folia Biologica
|
2008
|
vol. 56
|
issue 3-4
187-191
EN
The role of estrogens in hen reproduction is well established. However, the distribution of estrogen receptors in the chicken ovary is unknown. Therefore, the mRNA expression of alpha (ERalpha) and beta (ERbeta) estrogen receptors was examined within the ovaries of laying hens. Expression of ERs was determined by RT-PCR analysis. The presence of ERalpha and ERbeta mRNAs was found in the ovarian stroma and white, yellowish, small yellow and the largest preovulatory (F3-F1) follicles. ERalpha and ERbeta mRNAs were detected in the granulosa and theca layers of the walls of preovulatory follicles. The expression of ERalpha mRNA was markedly higher than ER? mRNA in all examined ovarian compartments. Within the ovary, the relative expression of both ER mRNAs depends on the follicular diameter and the layer of the follicular wall. The results demonstrate the expression of both ERalpha mRNA and ERbeta mRNA in all compartments of the chicken ovary, suggesting different pathways of estrogen action in the avian ovary. Much higher expression of ERalpha mRNA indicates that this form of estrogen receptor is predominant in the chicken ovary. The clarification of the mechanism of ER? and ER? participation in the ovarian functions of birds necessitates further experiments examining ERs at the protein level.
5

Simultaneous determination of plasma ovarian and thyroid hormones during sexual maturation of the hen (Gallus domesticus)

81%
Sechman A., Rzasa J., Paczoska-Eliasiewicz H., Hrabia A.
Folia Biologica
|
2000
|
vol. 48
|
issue 1-2
7-12
EN
The concentrations of ovarian steroids (estradiol ? E2, progesterone ? P4 and testosterone ? T) and thyroid hormones (thyroxine ? T4 and triiodothyronine ? T3) were determined in blood plasma of the domestic hen during sexual maturation and the initial period of egg lay. Blood samples were collected from Hy-Line pullets at 3 day intervals from days 87 to 144 day of life, i.e. 42 days before and 14 days after the onset of egg lay (OEL). Ovarian and thyroid hormones were measured by RIA methods. During sexual maturation an increase in ovarian steroids in the blood plasma was observed. The maximum E2 and P4 levels were recorded on day 6 and day 3 prior to OEL, respectively. In the case of plasma T level, an increase from 42 to 18 days before OEL followed by a decrease and a renewed increase from day 9 till OEL was observed. The relatively unchanged plasma level of T4 until day 9 before OEL decreased significantly just before the first oviposition while the T3 level gradually decreased between day 42 and day 9 before OEL, and then increased and again decreased from day 3 before till day 3 after OEL. During sexual maturation the following statistically significant coefficients of correlation between ovarian steroids and T3 were found: E2 vs. T3 ? r = -0.551 and P4 vs. T3 ? r = -0.373. There was no significant correlation between T and T3 or between the examined steroids and T4. The data obtained indicate that during sexual maturation of the domestic hen there is a negative relationship between the ovary and the thyroid gland.
6

mRNA expression and immunocytochemical localization of leptin receptor in the oviduct of the laying hen (Gallus domesticus)

81%
Grzegorzewska A., Paczoska-Eliasiewicz H. E., Rzasa J.
Folia Biologica
|
2008
|
vol. 56
|
issue 3-4
179-185
EN
The role of leptin in female reproduction is fairly well established in mammals, whereas reports concerning leptin action in birds are scarce. The aim of the present study was to detect leptin receptor (LEP-R) mRNA and to localize the leptin receptor protein in the oviduct of laying hens 2h after ovulation by the RT-PCR method and immunocytochemical staining. The RT-PCR reaction demonstrated expression of the long form of leptin receptor mRNA in all examined oviductal parts (infundibulum,magnum, isthmus and shell gland) and theweakest level was found in the isthmus. The expression of the short isoform was lower than the long formin all examined tissue samples and no differences between oviductal parts were observed. Immunostaining specific for leptin receptor was found in the walls of all examined oviductal parts. The intensity of the immunopositive reaction was the strongest in the epithelium of all examined parts of the oviduct and in the endothelium and muscles of blood vessels. The weakest immunopositive reaction was observed in tubular glands, the connective tissue layer and in circular and longitudinal muscles. The results obtained in this experiment suggest that the oviductmay be a target tissue for leptin,where this polypeptide hormonmay participate in egg formation and/or its transport through the oviduct of the domestic hen.
7

Effect of 9-cis retinoic acid (RA) on sex hormone secretion and RA receptor expression in chicken ovarian follicles

71%
Pawlowska K., Sechman A., Suchanek I., Grzegorzewska A., Rzasa J.
Folia Biologica
|
2008
|
vol. 56
|
issue 1-2
65-72
EN
Several lines of evidence indicate that retinoids, derivates of vitamin A, affect reproductive function in birds, however, the mechanism of their action in the ovary is still unknown. Therefore, the present study was designed (i) to show whether in the domestic hen 9-cis retinoic acid (9-cis RA), one of the retinoids, influences steroid secretion in vitro by white and yellow chicken ovarian follicles, and (ii) to detect expression of retinoic acid RXR receptor mRNA in these follicles. The white follicles (small: 1-4 mm, medium: 4-6 mm and large 6-8 mm in diameter) and the three largest yellow preovulatory follicles (F3-F1; 25-37 mm) were isolated from the ovary 3 h before ovulation. The granulosa layer was separated from the theca layer in the preovulatory follicles, which were subsequently divided into 4 equal pieces. The isolated whole white follicles or parts of the granulosa or theca layers were incubated for 24 h at 38oC in Eagle's medium in the following 4 groups: control, ovine LH (oLH; 10 ng/ml), 9-cis RA (100 ng/ml) and 9-cis RA + oLH. After incubation, the medium was collected for estradiol (E2) and progesterone (P4) determination while tissues were saved for protein assay. It was found that 9-cis RA affects steroid secretion from chicken ovarian follicles. It decreased E2 secretion from white follicles and from the theca layer of the two largest (F2 and F1) preovulatory follicles. 9-cis RA had no effect on oLH-stimulated E2 secretion by the white follicles and yellow F2 and F1 follicles, but it diminished E2 secretion by F3 follicles. As regards P4, the effect of 9-cis RA was opposite; it increased P4 secretion from the granulosa layer of all preovulatory follicles. 9-cis RA did not change oLH-stimulated P4 secretion by granulosa layers of F3 and F2 follicles, however, it inhibited oLH-enhanced P4 secretion from the F1 granulosa layer. In a separate experiment, the presence of mRNA encoding RXR was found in the stroma and all follicles of the chicken ovary by means of the RT-PCR technique. The results indicate that retinoids, acting by specific nuclear receptors, are modulators of follicular steroidogenesis in the chicken ovary.
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