REPRODUCTIVE SYSTEM Female Reproductive Organs Female Reproductive System

REPRODUCTIVE SYSTEM

Female Reproductive Organs

Female Reproductive System �Gonads = organs where gametes are formed �Gametes = sex cells �Ovaries – female gonads that produce eggs

Oogenesis �Formation of eggs by meiosis �Begins before birth with formation of primary oocytes �Process halts at birth �Begins again at puberty with maturation into secondary oocytes �One egg released (ovulated) every ~28 days until menopause

Ovulation �Released egg swept into fallopian/ uterine tube �Moves slowly towards uterus �Fertilization usually occurs in uterine tube

Male Reproductive System

Male Reproductive System �Male gonads – testes �Male gametes – sperm �Testes – located outside of the body to help maintain ideal temperature for sperm development • Descend from the abdominal cavity into the scrotum shortly before birth

Spermatogenesis �Formation of sperm through meiosis �Begins at puberty & continues until death �Occurs in seminiferous tubules of testes

The Journey of a Sperm �Epididymis – takes sperm from testes to ductus deferens • Diameter of pencil lead but 20 feet long • Coiled & bundled into C shape on posterior of testicle • Sperm do not have tails so movement by peristalsis

Epididymis

Ductus Deferens �Part of spermatic cord (bundle of artery, vein, nerve, muscle, & vas deferens) �Takes sperm from epididymis to ejaculatory duct �Ejaculatory duct connects to urethra

Vasectomy �Ductus deferens separated from spermatic cord, severed, & sealed

Accessory glands �Secretions mix with sperm to form semen �Seminal vesicles – secretion has sugar to nourish sperm �Prostate gland – secretion is alkaline to neutralize acidity of vagina �Bulbourethral gland - lubrication

Accessory Organs

Physiology of Reproduction �Erection – Dilation of arteries fills empty spaces in erectile tissue with blood, compressing veins �Emission – movement of sperm through the epididymis to ejaculatory duct �Ejaculation – exit of seminal fluid from urethra

Prenatal Development

Germinal Stage �First 2 weeks after fertilization �Egg + sperm = zygote �Cell Division starts within 24 -36 hours �Differentiation of cells – now called blastocyst �Implantation into uterus wall after ~ 7 days

Germinal Stage

Embryonic Stage �Weeks 3 through 8 �Development of body form • Head & tail cavities head, buds • Umbilical cord �Organogenesis (4 -5 wks) • Heart by ~Day 21 • Most formed by end of 7 th week • Embryo is 1 g and 1 inch long

Development of Placenta �Starts to develop in Week 4 �Placental blood barrier �Connected to baby by umbilical cord

Fetal Stage �Bone ossification �LOTS of cell division and growth �Full term at Week 38

Fetal Stage

PARTURITION �Oxytocin triggers labor • Positive Feedback Loop �First stage - amnion ruptures; fetus against cervix �Second stage – maximal cervical dilation to exit of fetus �Third stage – delivery of placenta