Morphological and Endocrinological Studies on Follicular Development during the Human Menstrual Cycle*

Abstract

In order to clarify the morphological dynamics of follicular development and its correlation with ovarian endocrine activity, the present studies were performed in 45 regularly menstruating women who underwent gynecological surgery. Ovarian venous blood was collected from 35 women during the follicular phase. Thirteen of these 35 women were ovariectomized. In addition, 11 pairs of ovaries were obtained from women during the luteal phase. The ovaries were sectioned serially at 2.5 micron and every 13th stained slice was examined to assess the sizes and numbers of atretic and nonatretic follicles. The follicles were divided into five stages: 0.4 less than or equal to approximately less than 1.0 mm, 1.0 less than or equal to approximately less than 2.0 mm, 2.0 less than or equal to approximately less than 4.0 mm, 4.0 less than or equal to approximately less than 6.0 mm, and 6.0 mm less than or equal to approximately in follicular diameter. Estradiol concentrations in ovarian venous plasma were low on both sides on days 1 and 3 of the cycle, whereas a clear asymmetry was found on day 5 before morphological recognition of the dominant follicle. Thereafter, estradiol increased proportionally to the growth of the dominant follicle, followed by a sudden drop when ovulation was imminent. An asymmetrical rise of progesterone occurred on day 10 and later which was sustained up to ovulation. A dominant follicle was recognized in 8 of 11 women between days 6 and 14. All dominant follicles were invariably associated with higher estradiol concentrations in the ipsilateral ovarian blood. Seven of 8 dominant follicles were on the side contralateral to the preceding corpus luteum. The mean diameters of the largest nonatretic follicles were 5.4 +/- 0.3 (SE) mm during the luteal phase as a whole and 4.7 +/- 0.7 mm during the late luteal phase. The mean diameters of the largest nonatretic follicles were not significantly different between the groups with or without the corpus luteum in the luteal phase. In terms of number and atretic rate, follicles of less than 4.0 mm in diameter did not change throughout the cycle in the presence or absence of the corpus luteum. In contrast, cyclic changes of growth and atresia occurred in the larger antral follicles.(ABSTRACT TRUNCATED AT 400 WORDS)

The Follicle-Stimulating Hormone (FSH) Threshold/Window Concept Examined by Different Interventions with Exogenous FSH during the Follicular Phase of the Normal Menstrual Cycle: Duration, Rather Than Magnitude, of FSH Increase Affects Follicle Development

“…According to the FSH threshold concept, increasing FSH concentrations should surpass a distinct level to initiate the final gonadotropin-dependent phase of follicle growth. Some researchers suggest selection of a follicle destined to gain dominance to occur during this period (23,25,26), although direct evidence to support this idea is lacking. Moreover, it has been hypothesized that follicles exhibit different degrees of FSH sensitivity at the time of recruitment.…”

Manipulation of Human Ovarian Function: Physiological Concepts and Clinical Consequences

“…Intrafollicular E 2 concentrations were up to 40,000-fold higher than those in peripheral plasma, and 20-fold higher concentrations of E 2 have been observed in venous blood draining the ovary containing the dominant follicle as compared with the contralateral side (88,89). It has been demonstrated in IVF patients that a correlation exists between the E 2 /androgen ratio in follicle fluid and follicular health and fertility potential of oocytes (90).…”

“…At the end of the luteal phase, the largest healthy follicles observed by morphological criteria have been described to be between 2 to 5 mm in diameter (10,89,154), and the number of recruitable follicles present is believed to be between 10 and 20 for both ovaries. Granulosa cells obtained from follicles in the late luteal phase are significantly more sensitive to FSH stimulation (as assessed by FSH-induced estrogen production in vitro) (154), suggesting that these healthy follicles will be recruited for the next cycle.…”

Mitochondrial function and mitochondria-induced apoptosis in an overstimulated rat ovarian cycle

“…OVARIAN CYCLE AND FOLLICULAR DEVELOPMENT are controlled by circulatory feedback between the ovarian hormones and the hypothalamic-pituitary axis (12) and the hormonal predominance of a dominant follicle determines its morphological changes and growth (13) by increasing diameter and the number of granulosa cells (28) whereas nondominant follicles become atretic.…”