Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 2000-2004
  • 1970-1974  (7)
  • Life and Medical Sciences  (7)
Source
Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Quantitative aspects of follicular development in the untreated and PMS-treated cyclic hamster (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 178 (1974), S. 139-143 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Hamsters injected at 0900 on day 1 of the cycle (metestrus) with either 0, 5 or 15 IU pregnant mare's serum (PMS) were killed at 1500 of days 1 to 4 of the cycle and the ovaries prepared for light microscopy and for a quantitative evaluation of follicular development. In the untreated cyclic hamster, the maximal number of preantral follicles with eight or more layers of granulosa cells occurred between the afternoon of day 4 (proestrus) and day 1, coinciding with the highest blood levels of FSH and LH. It is concluded that the elevated preovulatory levels of gonadotropins not only induce the ovulation of the mature antral follicles but at the same time recruit the next set of follicles for development during the new cycle.By the afternoon of day 1, treatment with either 5 or 15 IU PMS recruited more follicles into large preantral and incipient antral stages than in the untreated hamsters. However, by day 2 the pattern of follicular distribution was similar between the 5 IU PMS and untreated group whereas considerably more antral follicles had differentiated in the animals given 15 IU PMS. The ability of 15 IU PMS to elicit superovulation therefore depends on the levels being initially high enough to mature more follicles at critical stages of their development; the prolonged biological half life of PMS then sustains these follicles throughout the cycle.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091780112
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Follicular histology and physiological correlates in the preovulatory hamster (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 173 (1972), S. 95-107 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The surge in plasma luteinizing hormone (LH) in the proestrous hamster begins at 1430 (Turgeon and Greenwald, '72) and this is followed by a sharp increase in follicular and interstitially derived progesterone at 1500 (Norman and Greenwald, '71). The purpose of the present study was to relate various histologic events in the ovary of the preovulatory hamster to these physiological changes, dating from the LH increase between 1430 and 1500. The earliest maturational changes in the oocyte occurred at 1600 as the nuclear membrane began to disappear, correlating with an increase in the number of pycnotic nuclei in the surrounding cumulus cells and an abrupt reduction in mitotic activity in the membrana granulosa. It is possible that the latter event is related to increased progesterone secretion by the follicle at 1500. The most rapid increase in follicular diameter occurred between 2000 and 2200 - five to seven hours after the LH surge and was accompanied by a pronounced stromal edema especially of the medullary portion of the ovary. During this same time period, meiosis proceeded to the metaphase stage and the cumulus cells began to disperse to form the corona radiata. Of the eight hours required for the first meiotic division, four to six hours are spent in metaphase. The majority of animals (75%) ovulated by 0100 and all animals ovulated by 0200. Therefore, ovulation occurred 10 to 11 hours after the LH surge at 1500.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091730108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Effects of unilateral ovariectomy of the pregnant hamster on the remaining ovary (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 171 (1971), S. 221-225 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Unilateral ovariectomy of hamsters on day 1 of pregnancy resulted in an increase in weight of the remaining ovary by day 4, primarily by increasing the number of antral follicles. The ovulability of these follicles was tested by injecting 20 IU human chorionic gonadotropin (HCG) on day 12 of pregnancy. Following this treatment, the unilaterally ovariectomized animals ovulated 29.4 eggs whereas intact animals ovulated 16.6 eggs per ovary. In both instances, the number of antral follicles ovulated by HCG was between 40% and 50% of the number present. Luteal weight was unaltered by semispaying, indicating that the regulation of corpus luteum growth does not fit a negative feedback system.The ability of exogenous steroids to prevent ovarian compensation was assessed by injecting either progesterone (2 mg) or estradiol cyclopentylpropionate (1 μg) daily from days 8 to 11 of pregnancy. Either steroid injected into the semispayed hamsters prevented the expected increase in the remaining ovary in weight, follicular development and the ovulatory response to HCG. The same hormonal treatment of intact, pregnant animals slightly increased mean ovarian weight but did not affect follicular development.These results suggest that unilateral ovariectomy of the pregnant hamster, by decreasing peripheral level of ovarian steroids, partially reduces the inhibition of gonadotropin secretion and therefore leads to ovarian compensation.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091710202
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Effects of unilateral ovariectomy on ovulation and cycle length in 4- and 5-day cycling rats (1970)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 127 (1970), S. 1-7 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cyclic rats were unilaterally ovariectomized on each day of the estrous cycle and the ovulation rate of the remaining ovary was determined at the next expected ovulation by counting tubal ova.Holtzman rats, followed for three successive estrous cycles, were classified as 4- or 5-day cyclic animals. Control (i.e., intact) 4-day animals ovulated (2 ovaries) an average of 9.6 ± 0.6 eggs and 5-day rats ovulated 10.2 ± 0.2 ova. Estrus was designated as day 1 of the cycle. Unilateral ovariectomy on the morning of days 1 to 3 resulted in doubling the number of ovulations (complete compensatory ovulation) by the next estrus in all rats: an average of 10.5 eggs (N = 78 animals). Four-day animals did not compensate when semi-spayed after 8 PM of day 3, whereas, 5-day aniamls continued to double the number of ovulations until 2 AM of day 4.Unilateral ovariectomy of rats with previous 5-day cycles between 8 and 12 AM on day 1 shortened the expected cycle length by one day (60/73 rats). In contrast, only 19.4% of intact 5-day rats, spontaneously shortened their fourth cycle to four days. This effect of unilateral ovariectomy was only apparent in the cycle in which the operation was performed and was preventable by administration of 0.5 to 2.0 mg of progesterone on day 2. This suggests that unilateral ovariectomy on day 1 may have reduced the level of circulating progesterone enough to facilitate the release of LH one day earlier in the estrous cycle.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001270102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Of eggs and follicles (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 135 (1972), S. 1-3 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001350102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Effect of hypophysectomy and gonadotropin treatment on follicular development and ovulation in the hamster (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 139 (1974), S. 37-48 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In hamsters hypophysectomized on day 1 of the cycle (morning of ovulation) on days 1-28 post-hypophysectomy 99% of follicular development is limited to small and medium sized follicles with no more than five layers of granulosal cells. Since the largest preantral follicles on day 1 of the cycle have 10-12 layers of granulosal cells, it is evident that follicles become dependent on gonadotropins at an early stage of their maturation.The daily injection of 200 μg ovine follicle stimulating hormone (FSH) on days 8-11 post-hypophysectomy results in large antral follicles; when 10 μg ovine luteinizing hormone (LH) is then injected the animals ovulate 32 eggs. When 200 μg FSH on day 8 post-hypophysectomy is followed by 50 μg FSH on days 9-11, injecting LH results in the ovulation of nine eggs  -  comparable to the ovulation rate of intact hamsters. These experiments indicate that superovulation depends on sustained high levels of FSH whereas the ovulation of a normal number of eggs requires an initially high level of FSH and then much lower maintenance levels.When replacement therapy with 200 μg FSH for four days is started on the day of hypophysectomy (day 1) or day 2, follicles fail to develop past the six-seven granulosal layer stage. However, deferring the initial injection of FSH until day 3 results in antral follicles that are ovulated by LH (ovulation = 36 eggs). This suggests that functional corpora lutea inhibit the effects of FSH on follicular growth. Progesterone administered to hypophysectomized hamsters (days 8-11 post-hypophysectomy) increases the percentage of medium follicles at the expense of smaller stages. Progesterone injected daily along with FSH also prevents follicular development past the six-seven granulosal layer stage in 14 of 24 hypophysectomized animals.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001390103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Influence of unilateral ovariectomy on follicular development in cycling rats (1970)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 127 (1970), S. 9-14 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Ovarian follicular development was analyzed in intact and unilaterally ovariectomized cyclic rats. Holtzman rats, followed for three successive cycles, were classified as 4- or 5-day animals, with estrus designated as day 1. Intact 4- and 5-day animals were killed on each day of the estrous cycle and one ovary from each animal was saved for histology and examined for normal follicles larger than 352 μ. Cycling rats were unilaterally ovariectomized on day 1 and killed on each of the remaining days of the immediate estrous cycle and day 1 of the next cycle. The follicular population (normal follicles larger than 352 μ) was studied in the remaining ovary.During the estrous cycle of intact rats, there was a gradual increase in the number of follicles with a diameter of 518 to 571 μ and greater; however, the total number of follicles ranging in size from 352 to 571 μ and larger remained relatively constant. At day 5, in the 5-day cycling rat, the ovaries were depleted of follicles measuring from 395 to 570 μ.Following unilateral ovariectomy on day 1, there was a temporary decrease in the number of follicles larger than 448 μ. This agreed with the finding that animals semi-spayed on day 1 and injected with 20 I.U. human chorionic gonadotropin on day 2 (PM) did not ovulate, whereas intact animals ovulated an average of seven eggs after the same treatment. The remaining ovary of animals unilaterally ovariectomized on day 1 showed a significant increase by the next estrus in the number of follicles larger than 448 μ.The method of compensatory ovulation in the rat involved doubling the number of large follicles which ultimately matured during the estrous cycle. This resulted from increased proliferation of smaller follicles in the course of the cycle rather than from decreased follicular atresia.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001270103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...