[A girl looking pregnant].

The menstrual cycle includes a critical component known as the ovarian cycle, which undergoes two main phases each month—the follicular phase and the luteal phase. The follicular phase is variable and averaging around 14 days. Ovulation, triggered by a surge in luteinizing hormone (LH), marks the transition between the two phases. The second phase, the luteal phase, is relatively consistent, lasting approximately 14 days, and is marked by the activity of the corpus luteum. While a cycle...

Puberty is a critical phase, typically beginning between the ages of 8 and 13 in girls and 9 and 14 in boys, though timing can vary based on genetics, environmental factors, and overall health. This period is characterized by the development of secondary sexual characteristics and the attainment of reproductive potential. Endocrine changes underpin puberty, with hormonal surges of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) instigated by Gonadotropin-Releasing Hormone (GnRH)...

The secretory phase of the menstrual cycle, spanning from day 14 to 28 in a typical 28-day cycle, is a period of significant physiological changes in the female reproductive system. This phase commences immediately after ovulation and is characterized by the preparation of the endometrium for potential embryo implantation.
Following ovulation, the corpus luteum, a temporary endocrine structure, produces progesterone and estrogens. These hormones stimulate the growth and coiling of endometrial...

Female infertility is defined as the inability to conceive after a year of regular, unprotected intercourse and affects about 10–15% of couples worldwide. The primary cause of female infertility is ovulatory disorders, which hinder the release of eggs. These disorders can be classified as hypothalamic amenorrhea, polycystic ovarian syndrome (PCOS), premature ovarian failure, and hyperprolactinemic anovulation disorders.
Endometriosis, a condition characterized by abnormal growth of...

The proliferative phase typically occurs after menstruation and lasts between 6 to 13 days in a standard 28-day cycle. This phase involves the reconstruction of the endometrium, guided by estrogen produced by the developing ovarian follicle.
Notably, the stratum basale, the basal layer of the endometrium, including the basal parts of the uterine glands, remains unaffected by menstruation. Stem cells in this layer undergo mitosis, regenerating the stratum functionalis and thickening the...

The uterine cycle begins with the menstrual phase, which is considered day one of the cycle and typically lasts about five days. This phase is characterized by the degeneration and shedding of the stratum functionalis, the functional layer of the endometrium.
When fertilization does not occur, the corpus luteum deteriorates, causing a significant drop in the levels of estrogen and progesterone in the body. This hormonal decrease triggers the release of prostaglandins, which cause the uterine...