Transcript Lecture 12
Pelvis and Contents Reproductive Organs Bones of the Pelvis •Pelvic / hip girdle –Function: •Attaches the lower limbs to spine •Supports the viscera of the pelvis •Transmits the weight of the upper body –Contents: •Paired hip bones (coxal bone) –Unite with each other anteriorly and with the sacrum posteriorly –Bony pelvis: •Os coxae, sacrum and coccyx pg 408 Use lab work to learn bony landmarks of pelvis Os Coxae •Each pelvic bone during childhood: –Ilium •Superior region –Ishium •Posteroinferior region –Pubis •Anterior region pg 408, 423 pg 422 True and False Pelves •Separated by the pelvic brim •False Pelvis –Superior to the pelvic brim –Iliac blades –contains abdominal organs –attachment for muscles and ligaments to body wall •True Pelvis –Inferior to the pelvic brim –Space contains pg 408 •part colon •rectum •bladder •uterus/ovaries (females) •Pelvic Diaphragm –levator ani and coccygeus muscles –Supports pelvic organs –Seals inferior opening of bony pelvis –Lifts to help release feces during defecation pg 434 Sexual Dimorphism •Females –Tilted forward –Cavity is broad, shallow –Pelvic inlet oval and outlet round –Bones are lighter, thinner –Pubic angle larger –Ischial tuberosities shorter, more everted –Coccyx more moveable, straighter •Males –Cavity is narrow, deep –Smaller inlet and outlet –Bones heavier, thicker –Pubic angle more acute –Ischial tuberosities longer, face more medially –Coccyx less moveable, more curved pg 429 Perineum •Anus and external genitalia •Diamond shaped –Pubic symphysis anteriorly –Ischial tuberosities laterally –Coccyx posteriorly •Females: –External genitalia –Anus •Males: –Scrotum –Root of penis –Anus pg 487-488 Embryonic Development of the Sex Organs • Begin at week 5 as masses of gonadal ridges – Develop into the gonads • Sexually indifferent! • Both ducts are present in embryo, but only one develops: – Male • Mesonephric (Wolffian) ducts • Vas deferens, epididymis – Female • Paramesonephric (Müllerian) ducts • Uterus, oviduct, vagina External genitalia develops from same structures • Embryonic structure – Labioscrotal swelling – Urethral folds – Genital tubercle Male Scrotum Penile Urethra Penis Female Labia major Labia minor Clitoris www.bionalogy.com Descent of the Gonads •Male Development: –Testes partially descend at 3 months, finish at 7 months •Enter the scrotum –Vaginal process •Outpocketing of the peritoneal cavity •Eventually closes off •Forms tunica vaginalis –Gubernaculum •Fibrous cord •Extends from the testis to floor of scrotal sac –Final teste descent: •Shortening of gubernaculum •Increase in intra-abdominal pressure •Testosterone stimulation Page 283 Descent of the Gonads • Female Development – Descend only into the pelvis • Broad ligament blocks further descent – Gubernaculum • Guides ovaries • Attached to labia major • Becomes: – Round ligament of the uterus (inferior portion) – Ovarian ligament (superior portion) – Vaginal process • Outpocketing of peritoneum guides descent Puberty • Between ages 10 and 15 • Reproductive organs grow to their adult size – Reproduction becomes possible • Changes occur due to the increase in reproductive hormones in each individual – Testosterone in males – Estrogens in females Dimporhism at Puberty •Males •Females –Age 13 –Enlargement of the testes and scrotum –Secondary sex characteristics •Appearance of pubic, axillary, and facial hair •Enlargement of larynx •Oily skin –Increase in body size and musculature –Age 11 –Budding of breasts –Secondary sex characteristics •Increase in subcutaneous fat (hips and breasts) •Widening and lightening of the bones •Oily skin •Hair in pubic and axillary region –Menarche •Menstruation •Happens 1-2 years later Reproductive System •Overall function is to produce offspring •Genitalia = sex organs –Primary = Gonads •Ovaries, testes •Produce the sex cells / gametes –Eggs, sperm •Secrete sex hormones –Secondary = Accessory •Glands, ducts, external genitalia •Nourish and transport of gametes Male Reproductive System •Primary sex organ –Gonads = testes •Lie in the scrotum •Sperm-producing •Secondary sex organs –External Genitalia •Penis •Scrotum –Ducts •Epididymis –Efferent ductules –Duct of epididymis •Vas deferens –Ejaculatory duct •Urethra –Glands pg 407 •Seminal vesicle •Prostate •Bulbourethral Scrotum •Sac of skin and fascia •Hangs at the root of the penis •Contains the testes •Septum in midline divides right and left halves •Muscles: –Dartos •Inside skin of scrotum •Smooth muscle •Responsible for wrinkling of scrotal skin (warms) –Cremaster •Extends into scrotum from spermatic cord –Fibers from internal oblique •Skeletal muscle •Responsible for elevating and lowering the testes (warming and cooling) pg 417 Testes •Lie within the scrotum •Tunica vaginalis –Light sac partly covering each testes •Tunica albuginea –Fibrous capsule of the testes –Deep to tunica vaginalis –Divides testes into lobules •Lobules contain seminiferous tubules pg 450 Reproductive Duct System •Seminiferous tubules –“sperm factories” –Location of spermatogenesis –Converge into……. •Tubulus rectus –Straight tube that conveys sperm into…. •Rete testis –Lead to the…… •Efferent ductules –Lead to epididymis …. pg 450 Reproductive Duct System • Epididymis – Site of sperm maturation – Smooth muscle layer leads to ejaculation – Contains: • Head – Contain the efferent ductules » tube from rete testes to duct of epididymis – Ciliated simple columnar epithelium • Body and Tail – Duct of epididymis » Highly coiled » Leads into the vas deferens – Pseudostratified columnar epithelium with stereocilia » Resorb testicular fliud » Transfer nutrients and secretions to sperm stored in the epididymis Reproductive Duct System • Vas Deferens (Ductus Deferens) – Stores and transports sperm during ejaculation – Runs from epididymis to ejaculatory duct • ED then runs within the prostate gland and empties into the prostatic urethra – Layers: • • • • Pseudostratified epithelium Lamina propria Thick muscularis Adventitia – Vasectomy • Cut vas deferens, close off ends • Sperm STILL produced, but cannot exit the body • Reversible sometimes! pg 261 Reproductive System •Spermatic Cord –Collective name for structures associated with the scrotum –Passes through inguinal canal –Includes •Vas Deferens •Testicular arteries and veins (pampiniform plexus) •Lymphatic vessels •Cremaster muscle fibers •Nerves Cell Division • Mitosis – Events in which replicated DNA of original cell is divided into 2 new cells – Cell division with chromosome duplication and division 2 daughter cells = parent • Have Diploid = 2n number of chromosomes • Occurs in body (somatic) cells • Meiosis = Reductional division – Events that reduce the number of chromosomes (1/2 of the parent) • Have Haploid = n number of chromosomes • Occurs in sex cells Spermatogenesis • Production of sperm • Stages: – Stem cells = Spermatogonia (2n) – Mitosis • Formation of 2 daughter cells – Type A become precursor cells (2n) – Type B become primary spermatocytes (2n) – Meiosis • Primary spermatocytes undergo Meiosis I – 2 secondary spermatocytes (n) • Secondary spermatocytes undergo Meiosis II – 4 spermatids (n) – Spermiogenesis • Spermatids differentiate into sperm • Sperm cell (spermatozoan) – Head (acrosome), tail and midpiece – Controlled by FSH (pituitary gland) and testosterone (testes) Within Seminiferous Tubules • Sustentacular cells (Sertoli cells) – – – – – – – Surround the spermatogenic cells in the lumen Provide nutrients to spermatogenic cells Move cells toward tubule lumen Secrete testicular fluid Phagocytize cytoplasm shed by developing spermatids Secrete Androgen-binding protein (concentrates testosterone) Secrete Inhibin (hormone slows rate of sperm production) • Blood-testis barrier – In tight junctions between the sustentacular cells – Prevent escape of membrane antigens from sperm into the bloodstream Within Seminiferous Tubules • Myoid cells – Layers of smooth muscle cells – Contract to squeeze sperm thru tubules and out of testis • Interstitial cells (Leydig cells) – Make and secrete male sex hormone (androgens) – In CT between tubules Accessory Glands •Seminal Vesicles (2) –Lie on posterior surface of the bladder –Joins the vas deferens to form an ejaculatory duct –Contracts during ejaculation to empty –Secretion contains: •Fructose to nourish sperm •Prostaglandins to stimulate contraction of the uterus •Suppress immune response in females •Sperm motility enhancers •Enzymes that clot ejaculated semen in vagina, then liquefy it so sperm can swim out pg 407 Accessory Glands •Prostate gland –Inferior to bladder, anterior to rectum –Encircles the first part of the urethra –Contracts during ejaculation –Secretion contains: •Substances that enhance sperm motility •Enzymes that liquefy ejaculated sperm •Bulbourethral gland (2) –Inferior to prostate gland –Within urogenital diaphragm –Empties into spongy urethra –Produce a mucus •Neutralize urine in urethra •Lubricate semen for passage pg 407 Penis •Male external genitalia •Delivers sperm into the female reproductive tract •Anatomy: –Root •Attached end •Crura –Anchored to pubic arch, covered by ischiocavernosus muscle •Bulb –Secured to urogenital diaphragm –Body / Shaft •Free; not attached –Glans penis •Enlarged tip –Prepuce / Foreskin •Loose cuff around glans –Spongy urethra •Tube within penis pg 484 Penis •Erectile bodies –3 cylindrical bodies around the spongy urethra –Thick tube covered by DCT •Filled with smooth muscle, CT, and vascular spaces –Corpus spongiosum •Midventral erectile body •Distally forms the glans penis •Proximally forms the bulb of the penis –Corpora cavernosa •Paired, dorsal erectile bodies •Proximal ends are the crura of the penis (crus) –Covered by ischiocavernosus muscle •Make up most of the mass of the penis pg 484 Penis Innervation and Vasculature •Arterial supply –Branches of internal pudendal •Innervation –Branches of pudendal from sacral plexus provides sensory innervation •Parasympathetic –Engorgement of blood in erectile bodies = erection •Sympathetic –Contraction of smooth muscle in ducts and glands and bulbospongiosum muscle = ejaculation •Autonomic from inferior hypogastric plexus pg 491 pg 493 Female Reproductive System •Primary Sex Organs –Ovaries = gonads •Secondary Sex Organs –External Genitalia = vulva •Labia major + minor •Mons pubis •Clitoris –Ducts •Uterine tube = oviducts •Vagina –Glands pg 407 •Greater vestibular gland Anatomy •Ovaries (2) –Produce and store ova (eggs) –Produce estrogen –Tunica albuginea •Fibrous capsule that surrounds the ovary –Germinal epithelium •Covers the tunica albuginea •Mesothelium pg 407 Anatomy •Ovaries –Held in place by mesentery and ligaments made of peritoneum •Ligaments –Broad ligament •Supports uterus and oviducts –Suspensory ligament •Attaches ovaries to lateral pelvic wall –Ovarian ligament •Anchors the ovary to the uterus medially –Round ligament •Part of broad ligament •Attaches uterus to labia majorum pg 407 Oogenesis: production of eggs (ova) •Stem cells = oogonia undergo Mitosis –All of female’s oogonia produced while fetus –Oogonia become oocytes •Oogonia begin Meiosis I are called primary oocytes (2n) –Meiosis I is stalled before birth and until ovulation •During ovulation, Meiosis I completed and Meiosis II begins –Once Meiosis II begins, primary oocytes now called secondary oocytes (n) •Meiosis II is completed when sperm penetrates plasma membrane of the egg –When Meiosis II is completed, secondary oocyte is now called ovum (egg) •Meiosis II results in 4 daughter cells –1 ovum and 3 polar bodies (degenerate) Uterine Tubes • Also called oviducts, fallopian tubes •Begins laterally near ovary and ends medially at uterus •3 parts: –Infundibulum •Lateral, funnel shaped portion •Fimbrae on edges –Ampulla •Medial to infundibulum •Expanded portion •Site where fertilization occurs –Isthmus •Medial part of the tube •Layers –Visceral Peritoneum –Smooth Muscle –Ciliated simple columnar epithelium pg 456 Movement of Ova •Through the oviduct –Receives oocyte after ovulation –Peristaltic waves –Cilia lining tube –Contains cells to nourish ova •Ectopic pregnancy –Implantation of embryo outside of the uterus Uterus •Function: –Receive, retain, nourish fertilized egg (=zygote) •3 layers of wall: –Perimetrium (outer) –Myometrium (middle) –Endometrium (inner) •Portions: –Body –Fundus –Isthmus •Location: –Anterior to rectum –Posterosuperior to bladder pg 456 Cervix •Location: –Below the isthmus of the uterus –Considered the narrow neck of the uterus –Projects into the vagina •Function: –Keeps uterus closed and fetus within it during pregnancy (collagen) pg 456 • Location: Vagina –Inferior to the uterus –Anterior to the rectum –Posterior to the urethra and bladder •Birth canal •3 layers: –Adventitia –Muscularis –Mucosa •Rugae •Vaginal orifice •Hymen –Extension of mucosa –Incomplete wall / diaphragm pg 456 Female External Genitalia = “Vulva” •Mons pubis –Rounded pad over the pubic symphysis •Labia –Major •Fatty skin folds with hair –Minor •Smaller, hairless folds inside major •3 parts: –Vestibule »created by labia minor »opening for urethra and vagina –Central tendon –Fourchette »Junction of labia minor pg 488, 484 Female External Genitalia = “Vulva” •Clitoris –Superior to vestibule –Composed of erectile tissue –Homologous to the penis –Components: •Crura •Prepuce •Corpus cavernosa •No corpus spongiosum •Bulbs of vestibule –Engorge with blood to help grip the penis •Greater vestibular glands –Either side of vaginal opening –Secrete mucus to make intercourse possible pg 488, 484 Vasculature and Innervation •Vasculature –Uterine arteries from internal iliac and arcuate branches =uterus –Ovarian arteries from abdominal aorta and ovarian branches of uterine arteries = ovaries •Innervation –Branches of Pudendal nerve (hypogastric plexus & pelvic splanchnic nerves) pg 420 pg 454 Fertilization: sperm meets egg Path of sperm: Seminiferous tubulestubulus rectus rete testisefferent ductules duct of epididymis vas deferens ejaculatory duct urethrafemale’s vagina uterusoviduct Path of egg: ovaryperitoneal cavityinfundibulum (oviduct) oviduct The meeting: Sperm + egg meet in uterine tube sperm penetrates egg = fertilization Zygoteuterus for implantation in uterine wall