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Male Reproductive System
Chapter 8 Male Reproductive System
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Contents Introduction Histology and Spermatogenesis Androgen
Diseases and disorders
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Section I INTRODUCTION
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Male and female reproductive systems
Function together to produce offspring Female reproductive system nurtures developing offspring Produce important hormones
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Similarities and differences between males and females, but same goal: new life
Primary sex organs: gonads Testes in males Ovaries in females produce the gametes (sex cells) Sperm in males Ovum (egg) in females Endocrine function: secretion of hormones Accessory sex organs Internal glands and ducts External genitalia
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Male Reproductive System: Hormones
Hypothalamus Gonadotropin-releasing hormone (GnRH) Stimulates anterior pituitary to release FSH and LH Pituitary Follicle-stimulating hormone (FSH) – initiates spermatogenesis Luteinizing hormone (LH) – stimulates interstitial cells in the testes to produce testosterone Testis Testosterone Secondary sex characteristics Maturation of male reproductive organs Inhibin and avtivin
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Case: Unexpected Fracture 1
John Smith, 25 year old man Tripped while crossing the road and fallen awkwardly Had severe chest pain over the site of the impact History lived with his wife and worked as a chef Had bee attempting to have a baby for 2 years, with no success Nothing else is special
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Case: Unexpected Fracture 2
Physical Examination Tall with long arms and legs Swelling of breast tissue Lower ribs was very tender and was bruising over the skin Scanty body, pubic and axillary hair Testes were very small
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Case: Unexpected Fracture 3
Chest Radiography Several fracture in the right lower ribs because of a trivial fall The doctor concerned about The finding on clinical examination Severity of the fracture despite the relatively trivial fall.
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Case: Unexpected Fracture 4
Blood Test LH 35 U/L (normal < 10 U/L) FSH 65 U/L (normal < 10 U/L) Testosterone 4 nmol/L (normal 9-41 nmol/L) Sperm count Very low
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HISTOLOGY AND SPERMATOGENESIS
Section 2 HISTOLOGY AND SPERMATOGENESIS
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Histology and Spermatogenesis
Histology of the testis Spermatogenesis
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Anatomy of the Testis 鞘膜 白膜
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Seminiferous Tubules (细精管)
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Transverse Section of Seminiferous Tubules
支持细胞
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Spermatogenesis (精子发生)
65 – 70 days in human Three stages 12-21 days for the transportation of sperms in ducts epididymis - deferent duct - ejaculatory
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1st stage: formation of spermatocytes
Spermatogonia (精原细胞)are stem cells Least differentiated Lie in basal lamina (基底层) Divide continuously by mitosis (result 2n or diploid): daughter cells A (remains a stem cell) or B (goes on) When start to undergo meiosis are called spermatocytes (精母细胞)
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Blood-testis Barrier
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Blood-testis barrier Sperm surrounded by Sertoli* (sustenacular) cells: tight junctions Prevents escape of unique antigens seen as foreign These would activate the immune system Autoimmune response would cause sterility Sertoli cell (sustentacular cell) Tight junction
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The barriers may be disrupted, result in the exposure of sperms to the immune system.
And thus the production of antibody
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2nd stage: meiosis I Each primary spermatocytes (2n) undergoes meiosis I to become 2 secondary spermatocytes: Each secondary spermatocyte undergoes meiosis II to become 2 spermatids 4 total spermatids from each spermatogonium
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3rd stage: spermiogenesis (精子形成)
Head contains Nucleus with chromatid (genetic material) Acrosome(顶体) with enzymes for penetrating egg Midpiece: mitochondria spiraled around the core of the tail Tail is an elaborate flagellum (allows sperm to swim)
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Epididymis (附睾) Efferent ductules (输出小管) Duct of the epididymis (附睾管)
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Efferent Ductules At the head of epididymus
Lined by simple columnar epithelium Cilia and smooth muscle in wall help move sperm along Empty sperm into duct of the epididymus
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Duct of epididymis Pseudostratified (假复层) columnar epithelium
Highly coiled 6m long duct Pseudostratified (假复层) columnar epithelium Sperm mature (20 days) Sperm gain ability to swim Sperm stored in the tail of the epididymis in preparation for ejaculation. Maximal: for several months Pseudostratified columnar epithelium
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Ducts Deferens (输精管) 45 cm Thick layers of smooth muscle
Stores and transports sperm during ejaculation 固有层
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Prostate (前列腺) Size & shape of a chestnut (栗子)
Encircles 1st part of urethra (尿道) 3 types of glands Secrete citric acid (柠檬酸) and acid phosphatase Contribute to semen (精液)(milky fluid and enzymes) PSA measured as indicator of prostate cancer (“prostate specific antigen”) Fibromuscular stroma
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Ejaculatory duct (射精管)
The Sperm Pathway Sperm Pathway Ducts Deferens (输精管) Seminal vesicles (精囊) Testes Ejaculatory duct (射精管) Sperm Prostate gland Epididymis (附睾) Urethra Expulsion from the body
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Sperm
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Sperm A Health Man Produces
From puberty to old age 200 million every day Several trillion over a lifetime
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Seman Analysis (精液检查) Sperm "Count"
Sperm Morphology (Size, Shape, Appearance) Sperm Motility Chemical and Biochemical Semen Characteristics (pH, Color and Turbidity, Liquefaction, Viscosity.) Sperm Penetration Assays Post Coital Tests and Sperm-Cervical Mucus Interaction Antisperm Antibodies (Sperm "Allergy")
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Section 3 HORMONAL REGULATION
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Hormones Secreted by the Hypothalamus and Their Effects on Anterior Pituitary
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Endocrine Cells in Testes
Leydig Cell Testosterone Sertoli Cell Inhibin (抑制素) Activin (激活素)
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Metabolism of Testosterone
芳香化酶
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Physiology Effect of Testosterone
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Hypothalamus-Pituitary-Testes Axis
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The Relationship between GnRH and Testosterone in Lifetime in Male
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Testosterone Production Throughout the Life in Male
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DISEASES AND DISORDERS
Section 4 DISEASES AND DISORDERS
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Content Hypogonadism Therapeutic and abuse uses of androgens
Primary Secondary Tertiary Therapeutic and abuse uses of androgens Declining sperm counts
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Hypogonadism Primary Hypogonadism Secondary Hypogonadism
Caused by the disorder of testicular function itself Secondary Hypogonadism Caused by the pituitary gland Tertiary Hypogonadism Failure of GnRH secretion from hypothalamus Kallmann’s syndrome (卡尔曼综合征)
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Primary Hypogonadism Disease Treatment Klinefelter’s syndrome
Chromosomal abnormality that result in small testes and failure of secondary sex characteristics Mumps orchites (腮腺炎性睾丸炎) Cryptorchidism (隐睾症) Testicular damage from radiation or chemotherapy Treatment Steroid replacement To maintain secondary sex characteristics and sexual function The infertility is not reversible
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Case: Unexpected Fracture 1
John Smith, 25 year old man Tripped while crossing the road and fallen awkwardly Had severe chest pain over the site of the impact History: lived with his wife and worked as a chef Had bee attempting to have a baby for 2 years, with no success Nothing else is special
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Case: Unexpected Fracture 2
Physiological Examination Tall with long arms and legs Swelling of breast tissue Lower ribs was very tender (osteoporosis,骨质疏松症) Scanty body, pubic and axillary hair Testes were very small Chest Radiography Several fracture in the right lower ribs because of a trivial fall
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Case: Unexpected Fracture 3
Blood Test Lutinizeing hormone (LH) 35 U/L (normal < 10 U/L) Follicle stimulating hormone (FSH) 65 U/L (normal < 10 U/L) Testosterone 4nmol/L (normal 9-41 nmol/L) Sperm count Very low
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Therapeutic and Abuse Uses of Androgens
Therapeutic use Treat the symptoms of hypogonadism Abuse Teenagers: Improve the body image body-builders: Improve body mass Athlete improve muscle mass enhance aggression improve endurance faster recovery from injury
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Side-effect of Abuse Uses of Androgens
Men: Infertility - the testes will shrink and stop producing testosterone and sperm Women Virilization (女性男性化) , amenorrhoea (闭经)and liver cancer 海蒂•格里克 安得利斯 1997 -
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Declining Sperm Counts
Feminization (雌性化) of male wildlife populations caused by Chemicals in the environment that have oestrogenic effect, Including pesticides Various organochlorides Excreted oestrogens in sewage effluent For human?
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