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Comprehensive Overview of the
Reproductive System
Reproductive System
Functions of the Reproductive System
Produce sex cells/gametes (sperm cells in males and ova in females). Produce sex hormones (testosterone in males, estrogen and progesterone in females). (Male) Deliver sperm cells to the female reproductive tract. (Female) Retain, nurture, and protect the developing embryo or fetus.
Structure and Function of the Male Reproductive System
Seminiferous Tubules
Produce sperm.
Sertoli Cells
Support and regulate the cells that form sperm.
Leydig's Cells (Interstitial Cells)
Secrete testosterone.
Epididymis
Maturation and storage of sperm.
Vas Deferens
Carries sperm from the epididymis to the ejaculatory duct.
Urethra
Carries urine or sperm.
Seminal Vesicle
Produces a yellowish secretion (fructose, vitamin C) that nourishes and activates sperm.
Prostate Gland
Produces a milky fluid that activates sperm.
Bulbourethral Gland
Produces a secretion that: i. Cleanses the urethra from acidic urine. ii. Serves as a lubricant during sexual intercourse.
Pathway of Sperm
Seminiferous tubules → rete testis/vasa efferentia → epididymis → vas deferens/ductus deferens → seminal vesicle → ejaculatory duct → prostate gland → Cowper's gland/bulbourethral gland → urethra
Spermatogenesis
Spermatogonium undergoes mitosis to produce two daughter cells: type A (stem cell) and type B. Type B daughter cell moves towards the tubule lumen and grows into a primary spermatocyte. Primary spermatocyte undergoes meiosis I to produce two haploid secondary spermatocytes. Secondary spermatocyte continues meiosis II to produce four haploid spermatids. Spermatids undergo spermiogenesis to become mature sperm.
Structure and Function of the Female Reproductive System
Oogenesis
Before birth, oogonia undergo mitosis and grow into primary oocytes. Primary oocytes are surrounded by a layer of follicle cells to form primary follicles. During puberty to menopause, primary oocytes undergo meiosis I to form a haploid secondary oocyte and the first polar body. The secondary oocyte is found in the secondary follicle, which matures into a Graafian follicle. During ovulation, the Graafian follicle ruptures to release the secondary oocyte. When the secondary oocyte meets the sperm, it immediately undergoes meiosis II to produce an ovum and a second polar body. The ovum will fertilize with the sperm to form a zygote. The first polar body will undergo meiosis II to form two polar bodies.
Differences between Spermatogenesis and Oogenesis
| Spermatogenesis | Oogenesis | | --- | --- | | Produces sperm every day | Produces one ovum every 28 days | | Starts from puberty until death | Starts in the fetus and resumes from puberty until menopause | | One primary
Embryonic Development
Stages of Embryonic Development: Zygote → Morula → Blastocyst → Embryonic Disk → Gastrula → Neurula Processes in Embryonic Development: Cleavage/cell division, Morphogenesis, Differentiation, Growth Extraembryonic Membranes: Amnion, Yolk Sac, Allantois, Chorion
Fetal Development
First Trimester (0-12 weeks): Main period of organogenesis. Embryo's body structure begins to differentiate.
Heart begins beating at 4 weeks, and all organ systems are formed by the end of the 8th week.
Second Trimester (13-26 weeks):
Women become aware of fetal movements. Fetal heart rate can be detected.
Fetus opens its eyes and grows to about 30 cm in length.
Third Trimester (27-40 weeks):
Fetus's skin is wrinkled and covered with downy hair. Fetus turns in the uterus to assume a head-down position. Fetus experiences rapid growth.
Labor and Delivery
Initiation of Labor: Estrogen level rises, the placenta releases prostaglandins, and oxytocin is released by the posterior pituitary gland.
The combination of these hormones produces uterine contractions.
Stages of Labor:
Dilation Stage: Time from the appearance of true contractions until the cervix is fully dilated (about 10 cm). Expulsion Stage: Period from full dilation to delivery of the infant. Placental Stage: Delivery of the placenta.
Lactation
Prolactin (produced by the anterior pituitary gland) stimulates the production of milk in the mammary glands. Oxytocin (produced by the posterior pituitary gland) stimulates the release of milk from the mammary glands and causes uterine contractions during childbirth.
