Chapter 28 The Reproductive System BIO 211 Lab

Chapter 28: The Reproductive System BIO 211 Lab Instructor: Dr. Gollwitzer 1

• Today in class we will: – Identify the organs and anatomical structures of the male reproductive system • Testes – Spermatic cords – Inguinal canals • Reproductive tract – Seminiferous tubules – Spermatogenesis – Epididymis – Ductus deferens – Urethra • Accessory glands – Seminal vesicles – Prostate gland – Bulbourethral glands • External genitalia – Scrotum – Penis 2

What does it include? • Gonads: – Organs (testes and ovaries) that produce gametes (sperm and eggs) and hormones • Ducts: – Receive and transport gametes • Accessory glands: – Secrete fluids into ducts • External genitalia: – Perineal structures associated with reproductive system 3

Male Reproductive System Figure 28 -1, 7 th edition 4

Descent of the Testes • Testes form inside body cavity adjacent to kidneys • Move into lower abdominopelvic cavity • Then into scrotum between 7 months and birth Figure 28– 2 b, 7 th edition 5

Male Reproductive System: Spermatic Cords • Extend between abdominopelvic cavity and testis: – Consist of layers of fascia and muscle – Pass through inguinal canal – Descend into scrotum • Surround: – Ductus deferens – Blood vessels: • Testicular (gonadal) artery • Pampiniform plexus of testicular vein – Nerves – Lymphatic vessels 6

Male Reproductive System: Inguinal Canals • Passageways through abdominal musculature • Form during development as testes descend into scrotum • Inguinal hernia: – Presence of spermatic cord creates weak points in abdominal wall – May result in portion of intestine protruding into inguinal canal and/or scrotum 7

Figure 28 -3 8

Male Reproductive System: Scrotum (External Genitalia) • Pouch that encloses testis • Divided internally into 2 chambers • Raphe (seam) – partition between chambers marked by raised thickening on scrotal surface • Scrotal cavity – each testis lies in separate chamber; protects against spread of infection from one testis to another • Tunica vaginalis: – Serous membrane that lines scrotal cavity – Has parietal tunica vaginalis (lines scrotum) and visceral tunica vaginalis (covers testes) – scrotal cavity lies in between – Reduces friction between parietal and visceral surfaces • Scrotal skin – thin layer with underlying superficial fascia • Dartos muscle – smooth muscle within dermis; responsible for wrinkled scrotal surface with resting muscle tone • Cremaster muscle – skeletal muscle deep to dermis; contraction pulls testes closer to body during sexual arousal or temperature change (cold) 9

Male Reproductive System: Testes • Tunica albuginea: – Dense layer of CT with many collagen fibers – Deep to visceral tunica vaginalis covering testis – Fibers extend into substance of testis forming fibrous partitions (septa) • Septa - divide testis into lobules • Lobules – contain seminiferous tubules • Seminiferous tubules: – Slender, tightly coiled tubules (total ½ mile) – Site of sperm production • Rete testis – passageway/structure formed by looped seminiferous tubules • Efferent ductules – connect rete testis to epidiymus 10

Figure 28 -4 11

Male Reproductive System: Seminiferous Tubules • Delicate CT capsule surrounds each tubule • Within spaces between ST are blood vessels and large interstitial cells (Leydig cells) androgens (testosterone) • Within ST are sustentacular (Sertoli) cells: – “Nurse cells” – Are attached to tubular capsule and extend toward lumen between cells – Form blood-testis/sperm barrier – regulate transport to lumen of ST • Each ST contains cells undergoing spermatogenesis: – – = process of spermatozoa production Process begins at outermost layer of cells in ST Proceeds toward lumen At each step, cells move closer to lumen 12

Male Reproductive System: Spermatogenesis • Spermatogonia (stem cells) – divide by mitosis – 1 Primary spermatocyte and 1 spermatogonium • Primary spermatocyte: – Begins meiosis = reduction division ½ chromosome number in gametes – • Secondary spermatocytes • Spermatids: – Immature spermatozoa – Spermiogenesis • Spermatozoa: – Physically mature gametes, but functionally immature – Depend on other portions of reproductive tract for functional maturation 13

Figure 28 -5 14

Male Reproductive System: Reproductive Tract • Epididymis: – – Start of male reproductive tract Coiled tube (20+ ft!) bound to posterior border of testis Where sperm complete maturation Has 3 sections: • Head – superior, proximal to testis; receives spermatozoa from efferent ductules of testis • Body – extends along posterior margin of testis • Tail: – – Inferior portion Number of coils decrease Where spermatozoa are stored Recurves and ascends to connect with ductus deferens 15

Figure 28 -9 16

Male Reproductive System: Reproductive Tract • Ductus (vas) deferens: – Transports and stores sperm (for several months – in state of suspended animation with low metabolic rates) – Begins at tail of epididymus and ascends through inguinal canal into abdominal cavity – Ampulla – expanded portion just before seminal vesicles and prostate gland – Ejaculatory duct – short segment; from junction of ampulla with duct of seminal vesicle through prostate gland to urethra 17

Male Reproductive System: Reproductive Tract • Urethra: – From urinary bladder to tip of penis – Passageway used by urinary and reproductive systems – Divided into 3 regions: • Prostatic • Membranous • Spongy (penile) 18

Male Reproductive System: Accessory Glands • fluid component of semen • Seminal vesicles: – Paired glands that contribute 60% of semen volume – Secretions discharged into ejaculatory duct at emission (when peristaltic contractions occur in ductus deferens, seminal vesicles and prostate gland) • Prostate gland: – Small muscular gland that encircles urethra as it leaves bladder – Contributes 20 -30% of volume of semen – Secretions ejected into prostatic urethra • Bulbourethral glands (Cowper’s glands): – Very small, round glands at base of penis (in urogenital diaphragm/membrane) – Empty into urethra – Produce mucous secretion that lubricates tip of penis 19

Figure 28 -10 a 20

Male Reproductive System: Penis (External Genitalia) • Tubular, erectile organ through which urethra passes • Functions: – Conducts urine to exterior – Introduces semen into female’s vagina during sexual intercourse • Divided into three regions: – Root – fixed portion that attaches penis to body wall – Body (shaft) – tubular, movable portion – Glans – expanded distal end that surrounds external urethral meatus • Prepuce (foreskin) – fold of skin that surrounds tip of penis; surgical removal = circumcision 21

Male Reproductive System: Penis (External Genitalia) • Erectile tissue: – Makes up most of body of penis – Has vascular channels that become engorged with blood in response to stimuli erection – 3 cylindrical columns of tissue: • Corpora cavernosa (2) – erectile tissue that surrounds central arteries • Corpus spongiosum – surrounds penile urethra 22

Figure 28 -11 23

• Today in class we will: – Identify the organs and anatomical structures of the female reproductive system • Mesentery structures • Ovaries – Oogenesis • Ovarian structures after ovulation • Uterus – Uterine wall • External genitalia – – – Uterine tubes – Vagina Clitoris Prepuce Vestibular/Bartholin glands Labia majora Mons pubis • Mammary glands 24

Female Reproductive System Figure 28 -13, 7 th edition 25

Female Reproductive System: Mesentery Structures • Broad ligament: – Extensive mesentery that encloses ovaries, uterine tubes and uterus – Attaches to sides and floor of pelvic cavity, continuous with parietal peritoneum – Limits side to side movement and rotation • Mesovarium – thickened fold of mesentery that supports and stabilizes each ovary • Ovarian ligament – attaches ovary to uterus 26

Figure 28 -14 a, 7 th edition 27

Female Reproductive System: Ovaries • Small, paired organs near lateral walls of pelvic cavity • Position stabilized by: – Ovarian ligament – extends from uterus to ovary – Suspensory ligament – from ovary to pelvic wall; contains ovarian vein and artery (connected to ovary at ovarian hilum; where ovary attaches to mesovarium) • Appearance: – Pink or yellowish – Nodular consistency • Tissue layers: – Visceral peritoneum (germinal epithelium) – overlies … – Tunica albuginea – dense CT layer – Stroma – internal tissue; consists of: • Cortex - site of oogenesis = oocyte/gamete production • Medulla 28

Female Reproductive System: Oogenesis • Oogonia (stem cells): – Formed before birth – primary oocytes (daughter cells) between mo 3 -7 in utero • Ovarian follicles: – Specialized stuctures in cortex of ovaries – Where oocyte growth and meiosis I occur 29

Female Reproductive System: Oogenesis • Oogonia primary occyte • Primordial follicle surrounds primary oocyte (grouped in egg nests) • Primary follicle formed: – Follicle cells around primary oocyte become granulosa cells – Surrounded by thecal cells • Secondary follicle formed: – Primary oocyte still present – Follicle accumulates follicular fluid • Tertiary follicle formed: – Has an antrum (expanded central chamber) surrounded by granulosa cells – Primary oocyte secondary oocyte just before ovulation – At ovulation tertiary follicle releases secondary oocyte 30

Female Reproductive System: Ovarian Structures After Ovulation • Corpus hemorrhagicum: – Formed when empty tertiary follicle collapses, ruptured vessels bleed into antrum • Corpus luteum (CL): – Remaining granulosa cells divide and form a “yellow body” – Remains if pregnancy occurs – Degenerates approx 12 days after ovulation if no pregnancy • Corpus albicans: – Fibroblasts invade nonfunctional CL pale scar tissue (“white body” – = end of ovarian cycle 31

© 2012 Pearson Education, Inc. Figure 28 -16 -5 32

Female Reproductive System: Uterine Tubes • aka fallopian tubes, oviducts • Hollow, muscular tubes • Divided into three segments: – Infundibulum: • End closest to ovary • Funnel-shaped with finger-like projections (fimbriae) that extend into the pelvic cavity – Ampulla – middle segment – Isthmus - short segment connected to uterus – NOTE: fertilization usually occurs in region between ampulla and isthmus 33

Figure 28 -17 a, 7 th edition 34

Female Reproductive System: Uterus • Small, pear-shaped organ • Stabilized by suspensory ligaments • Regions: – Body (corpus): • Largest portion of uterus • Ends at isthmus (constricted region) • Fundus – rounded portion superior to attachment of uterine tubes – Cervix: • Inferior portion that extends from isthmus to vagina • Cervical os: – External orifice of uterus that leads into the cervical canal • Cervical canal: – Passageway opening to uterine cavity 35

Female Reproductive System: Uterine Wall • Myometrium: – Thick, outer muscular layer – Makes up 90% of uterus • Endometrium: – Thin, inner mucosa with glands and blood vessels – Sloughed during menses (periods) • Perimetrium: – Incomplete serous membrane covering fundus and posterior surface – Continuous with peritoneal lining 36

Figure 28 -18 37

Female Reproductive System: Vagina • Elastic, muscular tube • Between cervix and vestibule (= space bounded by female genitalia) • Rugae – folds on epithelial surface • Fornix – shallow recess that surrounds cervical protrusion into vaginal canal • Hymen – elastic epithelial fold that partially/ completely blocks entrance to vagina before onset of sexual intercourse • Vestibular bulbs – masses of erectile tissue on either side of vaginal entrance; same embryological origin as corpus spongiosum of penis 38

Female Reproductive System: Vulva • Vagina opens into central space (vestibule) bounded by small folds, the labia minora • Clitoris – anterior to vaginal opening; small rounded tissue projection equivalent to penis; contains erectile tissue • Prepuce – extensions of labia minora that surround clitoris • Vestibular (Bartholin) glands – same embryological origin as bulbourethral glands in males; lubricates vaginal area • Labia majora – larger folds that encircle labia minora • Mons pubis – adipose tissue deep to skin anterior to the pubic symphysis 39

Figure 28 -22 40

Analogous Reproductive Organs/Tissues Males Females Testes Ovaries Penis Clitoris Corpora cavernosa Erectile tissue Corpus spongiosum Vestibular bulbs Proximal shaft Labia minora Penile urethra Vestibule Bulbourethral glands Greater vestibular glands Scrotum Labia majora 41

Mammary Glands • Specialized organs (exocrine glands) of the integumentary system • Controlled by hormones of the reproductive system and placenta • Lie in subcutaneous tissue of pectoral fat pad • Structures: – Nipple – where mammary ducts open to surface – Areola – reddish brown skin around nipple; contains large sebaceous glands – Lobes – make up glandular tissue – Lactiferous ducts – formed by converging ducts from several lobes; 15 -20/ nipple – Lactiferous sinus – expanded chamber formed by enlargement of lactiferous duct near nipple 42

Figure 28 -23 a 43