Follicular phase

The female menstrual cycle is divided into four functional phases follicular, ovulatory, luteal, and menstrual.6 The follicular phase starts the cycle, and ovulation generally occurs on day 14. The luteal phase then begins and continues until menstruation occurs.6 The menstrual cycle is regulated by a negative-feedback hormone loop between the hypothalamus, anterior pituitary gland, and ovaries6 (Fig. 45-1). 

The median length of the menstrual cycle is 28 days (range 21 to 40). The first day of menses is day 1 of the follicular phase. Ovulation usually occurs on day 14 of the menstrual cycle. After ovulation, the luteal phase lasts until the beginning of the next cycle. 

As women age, circulating FSH progressively rises and ovarian inhibin declines. When ovarian function has ceased, serum FSH concentrations are greater than 40 international units/L. Menopause is characterized by a 10- to 15-fold increase in circulating FSH concentrations compared with concentrations of FSH in the follicular phase, a four- to fivefold increase in luteinizing hormone, and a greater than 90% decrease in circulating estradiol concentrations. 

Metabolic clearance of caffeine is altered according to menstrual phase and hormonal status in women (Lane et al. 1992). Clearance is slower during the late luteal phase compared to the follicular phase, prior to the onset of menstruation. However, the size of the effect and significance in everyday activity remains in question. 

The results 68% of the women treated with extracts from the follicular phase of the menstrual cycle shortened their own current cycle by an average of 1.7 days. A different 68% of the women treated with extracts from the ovarian phase of the menstrual cycle lengthened their own current cycle by an average of 1.4 days. Finally, underarm extracts taken following ovulation, in the luteal phase, had no effect on the... 

The follicular phase covers the development of the follicle, which involves an increase in its size due to an increase in follicular fluid, growth of the ovum (i.e. an increase in the contents of RNA and protein) and an increase in the number of cells that surround the ovum. These cells are of two types, the granulosa and the thecal cells. The role of these cells is to synthesise and secrete the steroid hormones oestrogens (mainly oestradiol). The precursor molecule for their synthesis is cholesterol. There is a division of labour between these cells the thecal cells convert cholesterol into the male sex hormones androstenedione and testosterone, which are released into the blood to be taken up by the granulosa cells where they are converted to the oestrogens (Figure 19.8). For details of pathways, see Appendix 19.1. 

Figure 19.12 Representation of changes in hormone levels during the menstrual cycle. Note that LH peaks about one day before ovulation. Oestrogen has two peaks one in the Luteal phase prior to LH surge and a smaller one in the follicular phase. Progesterone peaks in the follicular phase to stimulate development of endometrium.

In a later experiment, two pheromones from axillary odor of young women influenced the estrus cycle of other women (Stern and McClintock, 1998). Armpit secretion that appears odorless to humans was applied daily between the upper lip and nose of healthy young women and had two opposite effects depending on the menstrual phase of the odor donors. Secretion from nine donor women, collected on pads in their armpits during the follicular phase of their cycles... 

Daily heifers, after being brought into their follicular phase by injection of prostaglandin F20, were treated with cervical mucus or urine placed on... 

During the follicular phase of the menstrual cycle, one or more follicles are prepared for ovulation. FSH and estrogens are the most important hormones for this developmental process. Complete follicular maturation cannot occur in the absence of LH. Rupture of a mature follicle follows the midcycle peak of LH and FSH by about 24 hours. In humans, usually one mature ovum is released per cycle. During the luteal phase of the menstrual cycle and under the influence of LH, the ovarian granulosa cells of the corpus luteum become vacuolated and accumulate a yellow pigment called lutein. 

Administration during follicular phase suppresses the preovulation LH and prevents ovulation. 

Furthermore, these symptoms have a significant impact on a woman s interpersonal relations and general lifestyle and usually require the help of a mental health professional. Typically, at least five symptoms have been present in most menstrual cycles within the previous year, usually during the last week of the luteal phase, begin to remit within a few days after the onset of the follicular phase, and are absent during the week after menses ( 20). 

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