Follicular Development and Hibernation in European Ground Squirrels

In seasonally breeding mammals, in particular hibernators, reproduction underlies severe energetic and temporal constraints to enable the allocation of sufficient body fat reserves before winter. Thus, the timing of conception in spring can be crucial in terms of reproductive success. This study investigates follicular development in European ground squirrels (Spermophilus citellus) in three phases of the annual cycle: at vernal emergence, after weaning the offspring and shortly before hibernation. The animals were kept in outdoor enclosures within the natural habitat of the species. They were captured in weekly intervals, weighed and reproductive status was determined. Unilateral ovariectomy was scheduled such that the three periods were sampled. Numbers and diameters of tertiary follicles (TF) and corpora lutea (CL) in each ovary were determined, and plasma oestradiol and progesterone levels were analysed. The highest numbers of TF, including Graafian follicles, were found in ovaries at vernal emergence. During post-lactation, the number of TF was lower and active CL appeared in the investigated ovaries. Shortly before hibernation, active CL were present, but luteolysis had started in some individuals. Both oestradiol and progesterone secretion peaked after the termination of lactation and decreased before hibernation. The results demonstrate a second oestrus cycle in European ground squirrels after weaning, including an active luteal phase. This non-reproductive oestrus cycle with its endocrine output is an intriguing phenomenon. It may positively affect both prehibernatory fattening and reproduction in the subsequent season.

Download Full-text

Morphological Changes in the Rat Granulosa Cell Surface During Differentiation Induced by Estradiol and Gonadotropins

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079851 ◽

1977 ◽

Vol 35 ◽

pp. 484-485

Author(s):

P. Bagavandoss ◽

JoAnne S. Richards ◽

A. Rees Midgley

Keyword(s):

Cell Surface ◽

Granulosa Cell ◽

Morphological Changes ◽

Follicular Development ◽

Female Rats ◽

Functional Changes ◽

Group 4 ◽

Group 3 ◽

Group 5 ◽

Group 2

During follicular development in the mammalian ovary, several functional changes occur in the granulosa cells in response to steroid hormones and gonadotropins (1,2). In particular, marked changes in the content of membrane-associated receptors for the gonadotropins have been observed (1).We report here scanning electron microscope observations of morphological changes that occur on the granulosa cell surface in response to the administration of estradiol, human follicle stimulating hormone (hFSH), and human chorionic gonadotropin (hCG).Immature female rats that were hypophysectcmized on day 24 of age were treated in the following manner. Group 1: control groups were injected once a day with 0.1 ml phosphate buffered saline (PBS) for 3 days; group 2: estradiol (1.5 mg/0.2 ml propylene glycol) once a day for 3 days; group 3: estradiol for 3 days followed by 2 days of hFSH (1 μg/0.1 ml) twice daily, group 4: same as in group 3; group 5: same as in group 3 with a final injection of hCG (5 IU/0.1 ml) on the fifth day.

Download Full-text

Increased recruitment of intraepithelial lymphocytes into small intestinal mucosa during metabolic depression in ground squirrels

Gastroenterology ◽

10.1016/s0016-5085(01)81586-9 ◽

2001 ◽

Vol 120 (5) ◽

pp. A319-A319

Author(s):

H CAREY ◽

C FLECK

Keyword(s):

Intestinal Mucosa ◽

Intraepithelial Lymphocytes ◽

Ground Squirrels ◽

Small Intestinal Mucosa ◽

Metabolic Depression ◽

Small Intestinal

Download Full-text

Mono-follicular development is mediated via inhihin B pulses

Journal of the Society for Gynecologic Investigation ◽

10.1016/s1071-5576(97)86347-2 ◽

1998 ◽

Vol 5 (1) ◽

pp. 106A-106A

Author(s):

G LOCKWOOD ◽

S MUTTUKRISHNA ◽

N GROOME ◽

W LEDGER

Keyword(s):

Follicular Development

Download Full-text

FSH AND LH LEVELS IN THE INTACT AND UNILATERALLY OVARIECTOMIZED CYCLING RAT

Acta Endocrinologica ◽

10.1530/acta.0.0690267 ◽

1972 ◽

Vol 69 (2) ◽

pp. 267-280 ◽

Cited By ~ 7

Author(s):

Richard D. Peppler

Keyword(s):

Plasma Concentrations ◽

Follicular Development ◽

Slight Modification ◽

Oestrous Cycle ◽

Successive Cycle ◽

Unilateral Ovariectomy ◽

Subsequent Cycle ◽

Intact Rats

ABSTRACT Intact 5-day cycling rats were killed between 8–10 a. m. on each day of the oestrous cycle; experimental rats were unilaterally ovariectomized (ULO) at 9 a. m. on day 1 (oestrus) and killed between 8 and 10 a. m. on days 2, 3, 4 or 1 of the subsequent cycle. Pituitary and plasma concentrations of FSH and LH were measured in both groups of rats. Pituitary FSH concentration was measured by the Steelman-Pohley method with slight modification; plasma FSH by the Igarashi-McCann assay and pituitary and plasma LH concentration by the OAAD method. In intact rats, pituitary FSH values remained constant for the first three days of the cycle, increased on day 4 and reverted to early cycle values by day 5. Plasma FSH increased between days 2 and 3 and days 5 and 1. Pituitary LH concentration remained the same for days 1 and 2; increased two-fold on days 3 and 4, and increased further by day 5. Plasma LH increased between days 2 and 3; other differences between successive cycle days were not apparent. Following ULO on day 1, pituitary FSH increased steadily, but not significantly, for the remaining cycle. Plasma FSH did not change from day 2 through day 1 of the subsequent cycle. Pituitary LH remained low on day 2, increased sharply by day 3 and decreased (50 %) by day 4. Plasma LH also increased between days 2 and 3. Other differences between successive days following unilateral ovariectomy on day 1 were not apparent. Correlation of gonadotrophin activity with follicular development suggests that the mechanism of compensatory ovulation in the rat may be one of an increase in time of exposure to a constant gonadotrophic level for the duration of the oestrous cycle rather than to increased levels of the gonadotrophin.

Download Full-text

Magnetic resonance image attributes of the bovine ovarian follicle antrum during development and regression

Reproduction ◽

10.1530/reprod/120.2.311 ◽

2000 ◽

pp. 311-323 ◽

Cited By ~ 3

Author(s):

JL Hilton ◽

GE Sarty ◽

GP Adams ◽

RA Pierson

Keyword(s):

Magnetic Resonance ◽

Relaxation Rate ◽

Follicular Fluid ◽

Magnetic Resonance Image ◽

Follicular Development ◽

Physiological Status ◽

Proton Density ◽

Dominant Follicle ◽

Rate Heterogeneity ◽

Pixel Value

The magnetic resonance images and maps of bovine ovaries acquired at defined phases of follicular development and regression were studied to determine whether magnetic resonance image attributes of the follicular antrum reflect the physiological status of dominant and subordinate ovarian follicles. Ovariectomies were performed at day 3 of wave one, day 6 of wave one, day 1 of wave two and at >/= day 17 after ovulation. The timings of ovariectomies were selected to acquire growing, early static, late static and regressing follicles of the first wave and preovulatory follicles of the ovulatory wave. Pre-selection and subordinate follicles were also available for analysis. Serum samples were taken on the day of ovariectomy and follicular fluid samples were taken after imaging. Numerical pixel value and pixel heterogeneity in a spot representing approximately 95% of the follicular antrum were quantified in T(1)- and T(2)-weighted images. T(1) and T(2) relaxation rates (T(1) and T(2)), proton density, apparent diffusion coefficients and their heterogeneities were determined from the computed magnetic resonance maps. The antra of early atretic dominant follicles showed higher T(2)-weighted mean pixel value (P < 0.008) and heterogeneity (P < 0. 01) and lower T(2) heterogeneity (P < 0.008) than growing follicles. Subordinate follicles in the presence of a preovulatory dominant follicle had higher T(1), T(1) heterogeneity, proton density, proton density heterogeneity, and lower mean pixel value in T(1)-weighted images than subordinate follicles of the anovulatory wave (P < 0.04). T(1) relaxation rate heterogeneity and proton density heterogeneity were positively correlated with follicular fluid oestradiol concentration (r = 0.4 and 0.3; P < 0.04). T(2) relaxation rate heterogeneity was positively correlated with follicular fluid progesterone concentration (r = 0.4; P < 0.008). Quantitative differences in magnetic resonance image attributes of the antrum observed among phases of follicular development and regression coincided with changes in the ability of the dominant follicle to produce steroid hormones and ovulate, and thus were indicative of physiological status and follicular health.

Download Full-text

Evaluation of the hormonal and biochemical changes in obese and non-obese PCOS Iraqi women before and after vitamin D supplementation

International Journal of Drug Delivery Technology ◽

10.25258/ijddt.v9i3.2 ◽

2019 ◽

Vol 9 (o3) ◽

Author(s):

Suaad Muhssen Ghazi ◽

Fatin Shallal Farhan

Keyword(s):

Vitamin D ◽

Serum Vitamin ◽

Follicular Development ◽

High Body Mass Index ◽

Vitamin D Supplementation ◽

The Body ◽

Obese People ◽

Serum Vitamin D ◽

Before And After ◽

Granulose Cells

Vitamin D deficiency is common in women with polycystic ovarian syndrome. Vitamin D plays an important physiologic role in reproductive functions of ovarian follicular development and luteinization through altering anti-müllerian hormone signaling, follicular stimulating hormone activity and progesterone production in human granulose cells. Vitamin D is precipitated in adipose fat tissues, making it notable to be used for the body as a result; obese people with high body mass index are already highly expected to have low levels of serum vitamin D.

Download Full-text