Sexual Development Overview

A biological process starting at conception, shaping reproductive ability and sexual identity through various life stages.

The initial process where the sex chromosomes (XX or XY) determine an individual’s biological sex at conception.

The chromosomes (X and Y) that primarily determine biological sex.

The chromosome combination typically associated with a female.

The chromosome combination typically associated with a male.

The moment when a sperm fertilizes an egg, marking the start of a new life and early sexual development.

The typical number of chromosomes in a human cell.

Genetic, hormonal, and environmental factors affect sexual development and differentiation.

In male embryos, testosterone stimulates the Wolffian ducts to develop into male internal genitalia (epididymis, vas deferens, and seminal vesicles).

In male embryos, the Müllerian ducts (which would otherwise develop into female internal genitalia) regress, or break down.

In the absence of testosterone, the Müllerian ducts develop into the fallopian tubes, uterus, and vagina.

Initial identical structures in male and female embryos differentiate hormonally between weeks 9-12 to form the external genitalia.

Testosterone secreted by the testes is responsible for elongating the genital tubercle into a penis and fusing the urethral folds to form the penis's urethra.

Absence of substantial testosterone in female embryos causes the genital tubercle to become the clitoris and urethral folds to become the labia minora.

Testosterone influences the descent of the testes into the scrotum.

Puberty is the onset of sexual maturation, triggered by the hypothalamic-pituitary-gonadal (HPG) axis, around ages 8-16, influencing the production of sex hormones and secondary sexual characteristics.

A person's internal sense of being male, female, or another gender, which may or may not align with their assigned sex at birth.

Describes individuals whose gender identity does not align with the sex assigned at birth.

A person's romantic or sexual attraction to others.

Conditions where a person's sexual development does not follow the typical path due to chromosomal, hormonal, or genetic factors.

A condition in XY individuals where the body doesn't respond to male hormones, leading to the development of external genitalia that appear female, despite having male chromosomes and internal testes.

A genetic disorder causing the overproduction of male hormones (androgens) by the adrenal glands, which can lead to ambiguous genitalia in females.

Determined by chromosomes and hormones, it's the biological factors that classify a person as male or female.

The process of developing biological sex characteristics.

Changes in hormone levels (estrogen and testosterone) during puberty can cause mood swings, irritability, and heightened emotions in adolescents.

Puberty is a time when adolescents begin to explore their identity, including their sexual orientation, gender identity, and personal values. They become more aware of themselves as individuals.

During puberty, adolescents experience increased social pressures from peers. They try to fit in and find their place within their social groups.

Puberty marks a significant shift in cognitive abilities. Adolescents transition from concrete thinking to more abstract reasoning, allowing them to think critically, consider multiple perspectives, and make informed decisions.

As adolescents mature physically and mentally, they naturally desire more independence from their parents and guardians. They strive for autonomy and seek greater control over their lives.

Peer relationships become more important during puberty, as adolescents form close friendships, navigate social hierarchies, and learn about social dynamics.

Puberty can be a time when body image concerns arise, as adolescents compare themselves to others and may feel pressured by societal beauty standards.

Puberty is a period of rapid physical growth and development, including changes in height, weight, and sexual characteristics.

The first phase of the menstrual cycle, lasting around 5 days, where the uterine lining sheds and is expelled through menstruation. This happens due to a drop in estrogen and progesterone levels.

The second phase of the menstrual cycle, lasting around 13 days, where follicles in the ovaries mature under the influence of FSH, leading to the preparation of an egg for release.

The release of a mature egg from the dominant follicle in the ovary. This occurs around day 14 of a 28-day cycle, marking the most fertile period.

The fourth phase of the menstrual cycle, lasting around 14 days, where the ruptured follicle transforms into the corpus luteum, producing progesterone to thicken the uterine lining and prepare for implantation.

If the egg released during ovulation isn't fertilized, the hormone levels drop, causing the endometrium to break down and be expelled as menstruation.

Follicles in the ovaries mature under the influence of FSH, preparing an egg for release. The uterus rebuilds its lining in preparation for potential pregnancy.

Luteinizing Hormone (LH) is triggered by high estrogen levels and causes ovulation, releasing the egg from the follicle.

The corpus luteum is formed after ovulation from the ruptured follicle. It produces progesterone, thickening the uterine lining to prepare for implantation.

The menstrual cycle is controlled by a network of hormones and a feedback loop involving the hypothalamus, pituitary gland, ovaries, and uterus.

The hypothalamus releases GnRH, which triggers the pituitary gland to release FSH and LH.

The pituitary gland secretes FSH, stimulating follicle development in the ovaries, and LH, triggering ovulation.

The ovaries produce estrogen and progesterone in response to FSH and LH.

The uterine lining (endometrium) thickens in anticipation of pregnancy and sheds if no pregnancy occurs, responding to hormonal signals.

Hormonal regulation in the menstrual cycle operates through a negative feedback loop. For example, rising estrogen levels trigger LH release, which leads to ovulation. After ovulation, estrogen and progesterone levels rise, causing the uterine lining to thicken. If no pregnancy occurs, these hormone levels drop, causing menstruation.

Amenorrhea refers to the lack of menstruation, and it can be caused by factors such as pregnancy, hormonal imbalances, excessive exercise, or eating disorders.

Irregular menstrual cycles can be a sign of underlying health issues. Common irregularities include amenorrhea, irregular bleeding, excessive bleeding, and pain.