Download Trans Respiratory System and more Summaries Medicine in PDF only on Docsity!
HISTO_0 8 .1_MALE REPRODUCTIVE SYSTEM
BLESYLDA TATAD BUSTO. MD| February 24, 2025 S.Y. 2024 - 2025 | 2nd^ Semester
1 | Page
OUTLINE
MALE REPRODUCTIVE SYSTEM
I. TESTES
A. INTRATESTICULAR DUCTS
B. EXCRETORY GENITAL DUCTS
II. ACCESSORY GLANDS
III. PENIS
IV. CLINICAL CORRELATIONS
TESTES
- The testes are paired ovoid glands (~15 g each), suspended in the scrotum by the spermatic cords. They serve two primary functions : ✓ Exocrine : Production of spermatozoa in the seminiferous tubules. ✓ Endocrine : Synthesis and secretion of testosterone by Leydig cells.
- The anterior and lateral aspects of the testes are coated with a mesothelium that once was continuous with the mesothelium lining the peritoneal cavity.
- The testes are surrounded by three layers of testicular capsule: ✓ an outer tunica vaginalis ✓ middle tunica albuginea - composed of dense fibrous tissue ✓ inner tunica vasculosa – contains a network of blood vessels Structural Organization
- Tunica albuginea : Dense fibroelastic connective tissue capsule. Thickens at the posterior pole to form the mediastinum testis — the site of entry/exit of ducts, vessels, lymphatics, and nerves. Contains fibroblasts and myofibroblasts and smooth muscle cells , particularly in the posterior aspect close to the rete testis, which subject the seminiferous tissue to rhythmic contractions
- Septa radiate from the mediastinum to divide the parenchyma into ~250 pyramidal compartments – the testical lobules.
- Each lobule contains 1 to 4 coiled seminiferous tubules , where spermatogenesis occurs. Seminiferous tubules
- Basement membrane surrounded by myoid (contractile) cells.
- Long, highly convoluted tubules in the testis
- 1 - 4 seminiferous tubules per lobule of the testis
- Site of sperm production − 2 x 108 per day in the young adult
- 150 - 250 μm (diameter) 30-70 cm (length)
- Wall of seminiferous tubule is composed of the seminiferous epithelium lining its lumen and a slender connective tissue tunica propria ( type I collagen fibers interspersed with fibroblasts and myocytes )
- Converge upon a plexus of channels – the rete testis – labyrinth of epithelium-lined channels embedded in the mediastinum testis
- Lined with a complex, specialized stratified epithelium called germinal or spermatogenic epithelium
HISTO_0 8 .1_MALE REPRODUCTIVE SYSTEM
BLESYLDA TATAD BUSTO. MD| February 24, 2025 S.Y. 2024 - 2025 | 2nd^ Semester
2 | Page
Two types of cells ✓ Spermatogenic cells − mitotically and meiotically active ( dividing ) − 4 - 8 concentric cell layers which produce cells which become sperm. ✓ Sertoli cells : − Tall, columnar, non-dividing , supportive cells. − physically and metabolically support the precursor sperm cells − Apical membrane projects into lumina − Crystalloids of Charcot Bottcher (cytoplasmic inclusions) − Well-developed mitochondria and Golgi apparatus − Blood-testis barrier at basal compartment ▪ allow immune identical spermatogonia to cross barrier to make it immunologically unique ▪ control entry and exit of hormones ▪ separates the adluminal compartment from connective tissues − Maintain stem cell niche to ensure renewal of stem cells and differentiation of spermatogonia − Activated by FSH − Secretes other hormones, consumes unneeded portions of the spermatozoa during maturation phase of spermatogenesis − Secretions ▪ Anti-Mullerian Hormone - Suppresses formation of Mullerian duct ▪ Inhibins - Inhibits FSH ▪ Fructose-rich medium - Nutrition for spermatozoa ▪ Androgen-binding protein - Facilitates increased testosterone concentration Appendix testis (hydatid of Morgagni) − Tiny tag of tissue protruding from the anterosuperior aspect of the testis − May undergo torsion leading to loss of blood supply and necrosis (infarction) − Remnant of müllerian duct and present in approximately 80% of men. Leydig (interstitial) cells
- Located in connective tissue between seminiferous tubules
- Large, polygonal, eosinophilic cytoplasm with lipid droplet; Round during puberty
- Abundant SER and mitochondria
- Stimulated by LH (ICSH) to secrete testosterone , essential for: ✓ Development of male reproductive ducts and glands. ✓ Secondary sexual characteristics ✓ Maintenance of spermatogenesis
- Secretions: Testosterone, Androstenedione and DHEA (dihydroepiandrosterone) CLINICAL POINT Spermatocytic seminoma —an uncommon testicular neoplasm derived from germ cells but clinically and pathologically distinct from other more classic testicular tumors—usually affects men older than 60 years of age and is rarely malignant. Orchitis —inflammation of one or both testes—is usually caused by a viral, bacterial, or fungal infection. Viral orchitis, most commonly caused by the mumps virus, typically affects boys after puberty. Most cases of bacterial orchitis occur in young men via sexually transmitted pathogens (e.g., gonorrhea, trachomatis, Chlamydia ) or in older men with benign prostatic hypertrophy.
CLINICAL POINT
Relatively uncommon Leydig cell tumors —a type of stromal (sex cord) neoplasm of the testis—are often hormonally active and lead to virilizing or feminizing symptoms. The etiology is unknown, but disruption of the hypothalamic-pituitary-testicular axis causing excessive stimulation of Leydig cells may contribute to tumorigenesis. Prepubertal boys usually show signs of precocious virilization; adults often exhibit gynecomastia and loss of libido. Conclusive diagnosis is via scrotal ultrasonography
HISTO_0 8 .1_MALE REPRODUCTIVE SYSTEM
BLESYLDA TATAD BUSTO. MD| February 24, 2025 S.Y. 2024 - 2025 | 2nd^ Semester
4 | Page
Epididymis
- LE: pseudostratified columnar/cuboidal with stereocilia
- Long, extremely convoluted duct extending down the posterior aspect of the testis
- Tube of smooth muscle lined by a pseudostratitifed epithelium − From proximal to distal: muscular wall increases from singular to three layers (similar to ductus deferens) − Proximally: slow rhythmic contractility − Distally: intense contractions (SNS innervation) − Epithelial lining exhibits gradual transition from tall to short pseudostratified columnar epithelium − Principal cells of epididymal epithelium have tufts of very long microvilli or stereocilia (for absorption of excess of fluid from testis)
- Consists of a head at the upper pole of the testis, and a tail and the lower pole of the testis
- Functions in accumulation, storage and maturation of spermatozoa where it develops motility.
- Spermatozoa from the head of the epididymis are poorly motile and incapable of fertilizing ova in vitro
- Whereas spermatozoa from the tail of the epididymis are highly motile and capable of fertilizing ova in vitro
- This change in the spermatozoa is called capacitation.
- Functions to mature and store sperm cells (at least 20 days)
- Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens. Spermatogenesis Entire sequence of events wherein spermatogonia are transformed into spermatozoa Production of sperm cells Begins at puberty and continues throughout life Occurs in the seminiferous tubules Spermatogenic or Germ Cells – from the bulk of the epithelium, give rise to mature spermatozoa by spermatogenesis. Processes of Spermatogenesis
- Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty.
- Follicle stimulating hormone (FSH) modifies spermatogonia division. o One cell produced is a stem cell o The other cell produced becomes a primary spermatocyte
- Primary spermatocytes undergo meiosis
- Haploid spermatids are produced Divisions of Spermatogenesis
- Spermatocytogenesis – Mitosis of spermatogonia to become spermatocytes
- Meiosis – Maturation division of spermatocytes which reduce the chromosome number by half and produces spermatids
- Spermiogenesis – Spermatids are transformed directly into spermatozoa Three events during Spermiogenesis a. Acrosome formation − Golgi membranes coalesce to form an acrosomal granule − The acrosomal granule flattens around the nucleus to form an acrosomal cap b. Flagellum and midpiece formation − Centrioles migrate to the spermatid pole, opposite the acrosome − One centriole forms a flagellum − Mitochondria group around the base of the flagellum to form the midpiece c. Streamlining of spermatozoa − Nuclear condensation results in a pointed streamlined nucleus − Excess cytoplasm is shed as a residual body which is engulfed by the Sertoli cells Primary Spermatocytes ✓ The biggest of the spermatogenic cells with plenty of mitotic figures in their nuclei. ✓ These are seen in various stages of prophase because the stage of mitotic prophase is extremely prolonged. ✓ Undergoes first meiotic division and become transformed into secondary spermatocytes. Secondary Spermatocytes ✓ Small, dark staining nucleus with finely granular chromatin. ✓ These cells undergo spermiogenesis and become transformed into mature germ cells. ✓ Only few are seen in section because they transform rapidly into spermatozoa.
CLINICAL POINT
Infections of the epididymis are common after puberty. Bacteria most often cause inflammation of the epididymis, known as epididymitis. Scrotal pain and edema are characteristic. Chronic epididymitis is characterized histologically by accumulation of plasma cells and macrophages followed by fibrosis and duct obstruction. In severe cases, bilateral epididymitis can lead to male infertility.
HISTO_0 8 .1_MALE REPRODUCTIVE SYSTEM
BLESYLDA TATAD BUSTO. MD| February 24, 2025 S.Y. 2024 - 2025 | 2nd^ Semester
5 | Page
ACCESSORY GLANDS
- Produce secretions that are mixed with sperm during ejaculation to produce semen and that are essential for reproduction. Seminal Vesicles
- Each seminal vesicle is a long narrow gland that is highly folded on itself
- A complex glandular diverticulum of the associated ductus deferens
- Secrete 50-70% of the total volume of seminal fluid, most of the rest being secreted by the prostate gland
- Lumen of each seminal vesicle is highly irregular and recessed
- Honeycomb appearance at low magnification
- Lined by a pseudostratified tall columnar epithelium consisting of secretory cells with lipid droplets in the cytoplasm, giving it a foamy appearance.
- Epithelial cells contain brown lipofuscin granules and characteristically have variable nuclear shape and size
- Produces a yellowish viscid alkaline fluid which contains the following: − Fructose - Major energy source for sperm as well as inositol, citrate and other metabolites − Fibrinogen - Allows semen to coagulate after ejaculation − Vitamin C − Prostaglandins - Stimulates activity in female reproductive tract
- Prominent muscular wall is arranged into inner circular and outer longitudinal layers and is supplied by the sympathetic nervous system
- During ejaculation, muscle contraction forces secretions from the seminal vesicles into the urethra via the ampullae. Prostate Gland
- Dense organ that surrounds the urethra below the bladder
- Collection of 30 - 50 branched tubule-acinar glands embedded in a fibromuscular stroma in which smooth muscle contracts at ejaculation
- Composed of glands that surround and whose ducts pierce the wall of the urethra
- All lined by a simple or pseudostratified columnar epithelium
- Surrounded by a fibroelastic capsule, from which septa extend and divide the gland into indistinct lobes
- Distributed into three regions and are categorized as: mucosal, submucosal, and external (main) prostatic glands
- Secretion of the prostate gland is a whitish, thin fluid containing fibrinolysin, citric acid, serine protease (prostate-specific antigen, PSA), and acid phosphatase
- Corpora amylacea − Prostatic concretions − Found in the lumina − Contain primarily deposited glycoproteins and keratin sulfate − May become more numerous with age
- Transition zone − Surrounds the proximal prostatic urethra − Comprises about 5% of the glandular tissue − Contains the periurethral mucosal glands
- Central zone − 20%, surrounds the ejaculatory ducts − Contains the periurethral submucosal glands with longer ducts
- Peripheral zone − Contains main glands with longer ducts − Makes up the bulk of the gland − Approximately 70%
- Anterior fibromuscular stroma − n o glandular tissue and lies anteriorly
CLINICAL POINT
Spermatocytic seminoma —an uncommon testicular neoplasm derived from germ cells but clinically and pathologically distinct from other more classic testicular tumors—usually affects men older than 60 years of age and is rarely malignant. Semen analysis —used to assess male fertility or successful outcome of vasectomy— measures the amount of semen and other characteristics of sperm cells in an ejaculate.
HISTO_0 8 .1_MALE REPRODUCTIVE SYSTEM
BLESYLDA TATAD BUSTO. MD| February 24, 2025 S.Y. 2024 - 2025 | 2nd^ Semester
7 | Page
Decreased semen quality − frequently idiopathic (arising from unknown causes), is a major cause of male infertility − Features
- oligospermia (ejaculate volume >2 mL)
- sperm cell density less than 10-20 million/mL
- abnormal sperm morphology
- flagellar defects that impair sperm motility Epididymitis − result of sexually transmitted infections such as gonorrhea or Chlamydia infection and causes intrascrotal pain and tenderness − Persistent inflammation of the epididymis, such as that associated with gonorrhea infections, includes massive invasion by leukocytes into the infected duct, stimulating fibrosis that obstructs the epididymis and is a common cause of male infertility Prostate gland − Chronic prostatitis − Nodular hyperplasia or benign prostatic hypertrophy − Prostate cancer Erectile dysfunction − Also known as impotence − can result from diabetes, anxiety, vascular disease, or nerve damage during prostatectomy − Drug sildenafil – may alleviate the problem − by inhibiting the phosphodiesterase that degrades cyclic GMP in the smooth muscle cells of helicine arteries and erectile tissue
ADDITIONAL NOTES
Testis − Consists of two testes that contain spermatogenic cells, which produce sperm − Numerous excurrent ducts move sperm for storage and maturation into ductus epididymis − During ejaculation, sperm leave system via ductus (vas) deferens and penile urethra Scrotum − Testes located outside the body cavity in scrotum whose temperature is 2°C to 3°C lower than the body temperature − Lower temperature in scrotum due to sweat evaporation and pampiniform plexus − Countercurrent heat-exchange mechanism cools arterial blood as it enters the testes Excurrent Ducts − Released nonmotile sperm enter straight tubules and rete testis to ductuli efferentes − Ductuli efferentes in mediastinum conduct sperm to head of ductus epididymis − Epithelium lining ductuli efferentes is ciliated and nonciliated − Cilia in ductuli efferentes move sperm and fluid from seminiferous tubules to ductus epididymis − Nonciliated cells absorb much of the testicular fluid as it passes to ductus epididymis − Stereocilia line the surface of cells in ductus epididymis and vas deferens − Stereocilia absorb testicular fluid, and the principal cells phagocytose residual cytoplasm Sertoli Cells − Physical support, protection, nutrition, and release of mature sperm into tubules − Secretion of fluid for sperm nutrition and transport of sperm to excurrent ducts − Phagocytosis of residual cytoplasm of spermatids Male Hormones − Spermatogenesis dependent on luteinizing and follicle stimulating hormones produced by the pituitary gland − Luteinizing hormone binds to receptors on interstitial cells and stimulates testosterone secretion − Follicle-stimulating hormone stimulates Sertoli cells to produce androgen-binding hormone into seminiferous tubules to bind testosterone − Testosterone in seminiferous tubules is vital for spermatogenesis and accessory gland function − Sertoli cells produce inhibin, which inhibits FSH production from pituitary gland via negative feedback Seminal Vesicles − produce a yellowish, viscous fluid that contains a high concentration of sperm-activating chemicals, such as fructose , the main carbohydrate component of semen. − Fructose is metabolized by sperm and serves as the main energy source for sperm motility. − produce most of the fluid found in semen. Prostate Gland − produces a thin, watery, slightly acidic fluid, rich in citric acid, prostatic acid phosphatase, amylase and PSA. − enzyme fibrinolysin in the fluid liquefies the congealed semen after ejaculation. − PSA – useful for the diagnosis of prostatic cancer because its concentration often increases in the blood during malignancy. Bulbourethral Glands − produce a clear, viscid, mucus-like secretion that during erotic stimulation, is released and serves as a lubricant for the penile urethra
HISTO_0 8 .1_MALE REPRODUCTIVE SYSTEM
BLESYLDA TATAD BUSTO. MD| February 24, 2025 S.Y. 2024 - 2025 | 2nd^ Semester
8 | Page
