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Chapter 26

Chapter 26. Male reproductive system. Primary & secondary sex organs. Testes are the primary sex organ of the male reproductive system. They manufacture and store spermatozoa for fertilization of ova and reproduction of the species. Produce the sex cells or gametes = spermatozoa in males

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Chapter 26

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  1. Chapter 26 Male reproductive system

  2. Primary & secondary sex organs • Testes are the primary sex organ of the male reproductive system. They manufacture and store spermatozoa for fertilization of ova and reproduction of the species. • Produce the sex cells or gametes = spermatozoa in males • Produce testosterone • Secondary or accessory sex organs include: • The scrotum, epididymis, ductus (vas) deferens, urethra, ejaculatory duct, prostate gland, bulbourethral gland, seminal vesicles, and penis.

  3. Male reproductive organs

  4. Scrotum • Divided pouch of skin that contains the testes and is suspended outside of the body where it keeps the temp ~ 3.5 degrees cooler and prevents the sperm from dying. • Covered with stratified squamous epithelium and sparse pubic hairs it is divided in the middle by a septum that separates the two testicles. Externally the septum is marked by a seam the perineal raphe which extends from the inferior surface of the penis, around the scrotum to the margin of the anus. • In cold weather the scrotum can retract by contraction of the cremaster muscle (sk.m.) to bring the testicles up closer to the body for warmth. The cremaster muscle is an extension of the ext. oblique muscles. The dartos muscle, a thin layer of smooth muscle in the superficial fascia, causes the scrotum to wrinkle and thicken the skin in order to preserve heat in the cold, as well.

  5. Scrotum • The scrotum is richly supplied by many sensory and motor nerve fibers • It is also highly vascularized by the testicular artery to provide nourishment and oxygen to the spermatogenic apparatus necessary for production of sperm. • The pampiniform plexus is a network of veins that surround the testicular artery and serve as a heat exchanger to cool the blood in the testicular artery and allow for production of live sperm.

  6. Testes

  7. Testes • Location: • Contained within the scrotum inferior and outside of the abdominal cavity at the root of and posterior to the penis. • Structure: Enclosed in a serous sac tunica vaginalis from peritoneum • tunica albuginea “white coat”, fibrous outer capsule of the testes. Septal extensions of the t. albuginea form 200-300 lobules. • lobules – compartments; contain 1-4 seminiferous tubules • seminiferous tubules – tightly coiled “sperm factories” lined with germinal epithelium and sustentacular or Sertoli cells. The “S” cells protect the germinal epithelium and form a blood-testes-barrier to prevent the immune system antibodies from attacking the sperm • septum – divides testis into numerous wedge shaped compartments that arise from tunica albuginea. • Interstitial cells (Cells of Leydig)– produce androgenic hormones (testosterone, etc.); sourround seminiferous tubules and secrete fluid into surrounding interstitial fluid.

  8. Testes

  9. SEM of seminiferous tubules

  10. Spermatic ducts • Consists of those ducts that carry sperm from the seminiferous tubules in testes → urethra. • Includes the rete testis, efferent ductules, epididymis, ductus (vas) deferens and ejaculatory duct. • Rete testes network of vessels off of seminifeous tubules and lead into head of epididymis. • Efferent ductules are 12 small ducts that carry sperm from the seminiferous tubules to the epididymis. They are lined with clusters of ciliated cells that help the sperm move along.

  11. Epididymis • Coiled tube ~ 20 feet long on posterior surface of testicles. • Serve as storage sites and place of maturation of the sperm produced in the seminiferous tubules. • Has a head, body and tail and is lined with pseudostratified columnar epithelium covered with stereocilia. • Upon entering the epididymis it may take up to 20 days for sperm to mature and become motile and capable of fertilizing an ova. • Sperm are stored in the epididymis for 20 days before they are phagocytized and destroyed by surrounding epithelial cells. • At the time of ejaculation, the sperm are expelled from the tail of the epididymis into the ductus deferens. • Sperm do not begin swimming until ejaculated into the vagina. They are expelled from the sperm ducts by intense peristaltic contractions.

  12. Ductus (vas) deferens • Thick muscular tube that extends from tail of epididymis to the ejaculatory duct. • ~ 45 cm long and 2.5 mm in diameter. • Runs superiorly through the inguinal canal and spermatic cord up the anterior wall of pelvic cavity over and behind the urinary bladder and turns anteriorly to join the duct of the seminal vesicles which form the ejaculatory duct. • Propels sperm from epididymis to ejaculatory duct by peristaltic contractions. • Lined with pseudostratified columnar epithelium.

  13. Ampulla Seminal vesicle Ejaculatory duct Prostate gland Bulbourethral gland Ductus deferens Rectum Epididymis Glans of penis Prepuce Testis Scrotum

  14. Ejaculatory duct • A short segment of spermatic duct system the ejaculatory duct is formed by the convergence of the ductus deferens and seminal vesicle duct. • It is ~ 2 cm long and passes into the prostate gland where it empties into the urethra.

  15. Accessory glands of male reproductive system • Includes three sets of accessory glands: • The seminal vesicles • The prostate gland • The bulbourethral (Cowper) glands

  16. Seminal vesicles • Paired glands ~ 5 cm long and dorsal to the urinary bladder. Internally they are a complex labyrinth of ducts • Produce a yellowish secretion that is ~ 60% of the semen volume.

  17. Prostate gland • A bulbous gland situated at the base of the urinary bladder and consists of smooth muscle and connective tissue. • Composed of 30-50 tubuloacinar glands that empty into the urethra. • Milky secretion is ~ 30% of ejaculate volume.

  18. Bulbourethral gland • Two brownish spherical glands ~ 1 cm diameter. • They are located just superior to the bulb of the penis and their duct empties into the penile urethra. • Their secretion neutralizes the residual acidic urine in the urethra and serves as a pre-ejaculate to lubricate the penis for easy insertion into the vagina.

  19. Semen • Is a complex mixture of sperm and glandular secretions released upon ejaculation. • Typical volume is ~ 2 to 5 ml/ ejaculate. • Sperm count is 50 to 120 million/ ml. of semen. • It consists of: • ~ 10% spermatozoa • 30% prostatic fluids • 60% seminal fluids • High in fructose and enzymes to neutralize vaginal secretions and bacteria.

  20. Spermatozoa • Three distinct regions: 1) head, 2) mid piece and 3) tail. • Head is a flattened oval containing chromosomes. Tip contains Acrosomal cap with enzymes that will aid in penetration of the ova membrane. • Mid piece is joined to head by a short neck and contains centrioles and mitochondria. • Tail is a flagellum that propels the spermatozoa through the female reproductive tract.

  21. Spermatozoa

  22. Urethra • Consists of three regions in males • Prostatic urethra • Membranous urethra • Penile “spongy” urethra

  23. Penis • Tubular organ that empties urine through the distal urethra and introduces semen into the vagina during sexual intercourse. • Internal half is the root and external half is a shaft and glans. Together the penis and scrotum constitute the external genitalia of males. • The skin of the penis is loose and slides distally over the glans to form a “foreskin” or prepuce. • Internally the penis consists of 3 long cylindrical bodies of erectile tissue. These erectile bodies fill with blood during arousal and engorge the penis creating an erection. • The erectile bodies are: a single corpus spongiosum, a paired corpus cavernosa (dorsally).

  24. Penile structure Root = bulb + crus Shaft = body + glans Erectile tissue: Corpus cavernosa Corpus spongiosum Vascular supply: Internal pudendal art. Nerve supply: Parasym. → erection Sym. → ejaculation

  25. Urinary bladder Ureter Ampulla Seminal vesicle Ejaculatory duct Prostate gland Bulbourethral gland Bulb Crus Ductus deferens Corpus cavernosum Corpus spongiosum Epididymis Testis Urethra Glans of penis Penis

  26. Chapter 26 Female reproductive system

  27. Primary sex organ • Ovaries suspended in the retroperitoneal abdominal cavity, superior and lateral to the uterus. They contain the ova for reproduction of the species. • They are somewhat almond shaped and are ~3 cm ↑, 1.5 cm → and 1 cm thick. • Each ovary contains 6 – 7 million ova and only a single ova is released at the time of ovulation.

  28. Female reproductive system

  29. Primary and secondary female sex organs • Ovaries are the primary female sex organs that manufacture and release a single ova for fertilization with each ovarian cycle. • Secondary accessory sex organs include: • The mons pubis, labia minora, labia majora, clitoris, vagina, cervix, uterus, fallopian tubes, fimbria and mammary glands.

  30. Ovary • Structure: • Tunica albuginea – fibrous outer covering on ovary. • Cortex – outer layer of ovary where the oocytes reside in primordial follicles “little bags” before maturation. • Follicles – tiny scale-like structures that contain the ova. • (Graafian or vesicular follicle) – a mature follicle that bulges out onto the surface of the ovary just prior to ovulation (release of the ova). Only 1 ova is released. • Corpus luteum – luteal body left after ovulation. • Medulla – inner connective tissue core of the ovary, contains blood vessels and nerves.

  31. Ovary

  32. Ovary • Ligaments– ovarian ligament anchors ovary to uterus; suspensory ligament anchors ovary to pelvic wall; mesovarium ligament suspends ovary in between uterus and fallopian tubes. • Both suspensory and mesovarium form broad ligament which tents over the uterus and supports the uterine tubes, uterus and vagina. • It receives its vascular supply from the ovarian artery and the ovarian branch of the uterine artery. • Function of ovary: • a. To produce ova for fertilization • b. Produce estrogen and progesterone

  33. Internal female reproductive organs

  34. Uterine or Fallopian tubes • Consist of fimbriae, infindibulum, ampullae, and isthmus. • Fimbriae are finger like ciliated projections at proximal end of infindibulum. They have a wave-like motion to sweep the ova toward the infindibulum. • The infindibulum is lined with cilia. At the time of ovulation the cilia beat toward the opening into the fallopian tube pulling the free ova inward, moving it along by peristaltic contractions into the ampullae.

  35. Uterine or Fallopian tubes • Fertilization of the ova occurs in the ampullae near the infindibulum. • The fallopian tubes are made of smooth muscle and are lined with ciliated columnar epithelium and are supported by a short mesentery called the mesosalpinx, a part of the broad ligament.

  36. Colorized SEM of fallopian tubes

  37. Ovaries, fallopian tubes and uterus

  38. Uterus • Is a thick muscular organ where implantation of the fertilized ovum occurs for development of the embryo into a fetus. • Location – within retroperitoneal pelvic cavity, covered by visceral peritoneum. • Structure –looks like an inverted pear • Consists of a fundus, body and cervix. • Fundus is the dome of the uterus • Body is the main portion • Cervix is a thick circular muscular ring that opens into the vagina

  39. Uterine wall layers and blood supply • Layers of the uterine wall include: • endometrium – mucosal layer of simple columnar epithelium with secretory cells and ciliated cells underlain by a thick lamina propria. • Two stratum makeup the lamina propria: • Functionalis is highly vascular and under ovarian hormonal control. It is shed at menstruation if an ovum is not implanted. • Basalis forms a new functionalis layer after menstruation. • myometrium – thick muscular layer of interlacing bands of smooth muscle. • perimetrium – outer most serous layer = visceral peritoneum

  40. Uterine wall layers and blood supply

  41. Uterus

  42. Vagina • Hollow thin walled tube that receives the penis during sexual intercourse and serves as the birth canal at the time of partuition (birth). • Inferior to the uterus, the cervix opens into the vagina. Area of the vagina that encircles the cervix is called the fornix. • Consists of three layers: Outer fibrous CT adventitia; middle muscularis of smooth muscle and inner mucosa with transverse rugae. • Lined with stratified squamous epithelium • Vaginal orifice opens to the exterior and in virginal women is covered by an incomplete diaphragm called the Hymen

  43. Sagittal view of female reproductive tract

  44. External genitalia or Vulva = Pudendum • mons pubis – fatty area anterior to the pubic symphysis; covered with pubic hair. • labia majora – large fatty skin fold running posteriorly to the mons; the female homologue of the male scrotum. • labia minora – smaller fatty skin fold; medial to the labia majora. • vestibule – area surrounded by the labia minora; contains the vaginal and urethral openings; also contains the vestibular glands which are responsible for secreting mucous

  45. External genitalia or Vulva = Pudendum • clitoris – small protruding structure of erectile tissue (corpus cavernosa) located anterior to the vestibule and within the prepuce (hood). • Consists of the glans and crus (similar to penis) • is the female homologue of the male penis and is highly sensitive to touch. • Hooded by a fold of skin called the prepuce of the clitoris.

  46. External genitalia

  47. External genitalia Urethral orifice Glans Vestibular bulb Clitoris Crus Vestibule Greater vestibular gland

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