In this cute video, we explore the female sexual cycle in detail, from the follicular phase to the luteal phase. Learn about hormonal regulation and how it affects the menstrual cycle. Don't forget to subscribe for more educational content on embryology and women's health.
⌚Time stamps:
Introduction 00:00
Hormonal regulation of the cycle 00:39
Division of the female sexual cycle 1:43
Ovarian Cycle 2:12
Uterine Cycle 5:00
If Fertilization occurs 6:37
If fertilization does not occur 7:25
What is the Female Sexual Cycle?
The female sexual cycle is a set of cyclic changes that occur in the ovaries and uterus, preparing the woman's body for a possible pregnancy. This cycle has an average duration of 28 days, although it can vary between 21 and 35 days. Each cycle begins on the first day of menstruation and extends until the beginning of the next menstruation.
The ovarian cycle is divided into three main phases:
1. Follicular Phase:
The follicular phase begins on the first day of menstruation and lasts until ovulation.
During this phase, folliclestimulating hormone (FSH) stimulates the growth of several ovarian follicles. Each follicle contains an immature oocyte surrounded by follicular cells. Of the several follicles that begin to develop, only one becomes the dominant follicle.
This follicle grows larger than the others and begins to produce large amounts of estrogen, which has effects on the uterus and pituitary gland.
Estrogens produced by the dominant follicle have multiple functions, including proliferation of the endometrium and regulation of the hypothalamicpituitary axis through negative and positive feedback, culminating in an LH surge.
2. Ovulation:
Approximately halfway through the cycle, a sudden increase in the level of LH (luteinizing hormone) triggers ovulation.
The Graafian follicle ruptures and releases the secondary oocyte into the fallopian tube. This event usually occurs around day 14 of a 28day cycle.
Ovulation is crucial for fertility, since it is the moment when the oocyte is available to be fertilized by a sperm.
3. Luteal Phase:
The luteal phase begins immediately after ovulation and extends until the start of the next menstruation, generally lasting between 12 to 16 days.
After ovulation, the remaining cells of the ruptured follicle transform into the corpus luteum, a glandular structure that secretes progesterone and estrogen.
These hormones keep the endometrium in a receptive state for the possible implantation of an embryo.
If fertilization does not occur, the corpus luteum degenerates and becomes the corpus albicans, which causes a decrease in progesterone and estrogen levels, thus initiating a new menstrual cycle.
The uterine cycle consists of several phases that coincide with the phases of the ovarian cycle:
1. Menstrual Phase:
The menstrual phase marks the beginning of the uterine cycle and is characterized by the shedding of the functional layer of the endometrium, which manifests as menstrual bleeding. This occurs due to the drop in progesterone and estrogen levels.
Duration: This phase typically lasts 3 to 5 days, although it can vary.
2. Proliferative Phase:
Under the influence of estrogen produced by the dominant follicle, the endometrium regenerates and thickens. This phase extends from the end of menstruation until ovulation.
The main objective of this phase is to prepare the endometrium for the possible implantation of an embryo.
3. Secretory Phase:
After ovulation, progesterone secreted by the corpus luteum transforms the endometrium into a secretory structure, rich in nutrients and blood vessels, ideal for embryo implantation.
Duration: This phase lasts from ovulation to the start of the next menstruation, approximately 14 days in a typical 28day cycle.