Reproductive Hormones

Reproductive Hormones Sex hormones are synthesized from cholesterol (a fatty acid) and secreted throughout a person's lifetime at different levels. Male gonads (testes) produce sperm. Female gonads (ovaries) produce egg. Fusion of egg and sperm occur via fertilization to produce a zygote. The zygote undergoes division to become an embryo, which eventually becomes a fetus.

Male Reproductive System

Male Reproductive System Sex hormones: androsterone and testosterone. Functions of Testosterone: Testosterone is a male hormone which is produced by the testes.once a boy reaches puberty. It triggers the changes in a boy's body which turn him from a boy to a man. * Functions of androsterone: The function of the androsterone receptor protein is to stimulate transcription of certain genes in response to a hormone signal.

Male Reproductive System Hypothalamus and pituitary gland control production of sperm and sex hormones in the testes. Anterior pituitary produces and stores: The anterior pituitary produces six major hormones, and the posterior pituitary stores two hormones originating in the hypothalamus. The pituitary's target endocrine glands are the thyroid, adrenal gland, and the gonads. Through these glands it Controls on the development of sexual organs and Physical properties that distinguish men from women sound and body shape and size.

Male Reproductive System At puberty, hypothalamus secretes gonadotropin-releasing hormone (GnRH). GnRH activates anterior pituitary to release Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH). LH stimulates the development of the testes. FSH activates the testes' sperm-forming cells"

Once high levels of testosterone are detected by the hypothalamus, a negative feedback system is activated. Testosterone inhibits LH production by the pituitary by deactivating the hypothalamus.

Male Reproductive System Negative Feedback for FSH and LH.

Female Reproductive System

Female Reproductive System Sex hormones: Estrogen Progesterone

Female Reproductive System Oogenesis and Ovulation Ovaries contain fibrous CT and groups of cells called follicles. Follicles: Primary oocyte (undergoes meiosis to form ovum) and granulosa cells (provides nutrition for oocyte). Each ovary contains 400 000 follicles at puberty…many develop during each cycle, but only one reaches maturity.

Female Reproductive System

Female Reproductive System FSH & LH released. FSH stimulates growth of an ovarian body LH also promotes growth of the corpus luteum (a yellow, progesterone-secreting mass of cells that forms from an ovarian follicle after the release of a mature egg) as the ovary prepares to release the egg into the uterus. Granulosa cells divide. Primary oocyte undergoes meiosis I to form a secondary oocyte and polar body. As granulosa cells grow around the secondary oocyte, a fluid-filled cavity forms (antrum). Secondary oocyte presses against and eventually ruptures the ovarian wall.

Female Reproductive System Secondary oocyte released from ovary and enters fallopian tubes. Remaining follicle cells form the corpus luteum. If pregnancy does not occur within 10 days, the corpus luteum degenerates and leaves a scar (corpus albicans).

Female Reproductive System After ovulation, the secondary oocyte begins meiosis II. Unequal division occurs to form an egg (ovum) and a polar body. Overall…one primary oocyte becomes 1 ovum and 3 polar bodies (discarded).

Female Reproductive System

Female Reproductive System Menstrual Cycle 28 days. 4 phases: menstruation follicular ovulation luteal

Female Reproductive System Flow Phase (days 1 to 5) Shedding of endometrium (menstruation). Used to mark beginning of menstrual cycle.

Female Reproductive System Follicular Phase (days 6 to 13) Development of follicles in ovary. Estrogen secreted. Triggers thickening of endometrium.

Female Reproductive System Ovulatory Phase (day 14) Secondary oocyte released from ovary. Corpus luteum develops.

Female Reproductive System Luteal Phase (days 15 to 28) Corpus luteum secretes estrogen and progesterone. Progesterone continues to stimulate growth of endometrium and prepares uterus for an embryo.

Female Reproductive System If fertilization of ovum does not occur, concentration of estrogen and progesterone decreases. Weak uterine contractions cause endometrium to pull away from uterine wall. The shedding of the endometrium marks the beginning of the next cycle.

Female Reproductive System

Female Reproductive System FSH & LH regulate control of estrogen and progesterone. Estrogen and progesterone control the FSH & LH.

*Males and females both have male and female sex hormones, but in varying levels.

عمل الطلاب: محمد احمد مهاجري ماجد الاسمري هاني الغامدي مشاري الحربي فيصل المالكي تحت اشراف: د. عبدالرحمن العجلان