1 / 24

Histology of Male Reproductive System

Histology of Male Reproductive System. Lecture Objectives. Describe the histological features of the male reproductive system. Male Reproductive System. The male structures of reproduction include the: testes , a system of ducts ductus epididymis ductus deferens ejaculatory duct

kenaz
Download Presentation

Histology of Male Reproductive System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Histology of Male ReproductiveSystem

  2. LectureObjectives • Describe the histological features of the male reproductive system

  3. Male ReproductiveSystem • The male structures of reproduction includethe: • testes, • a system ofducts • ductus epididymis • ductus deferens • ejaculatoryduct • urethra • accessory sexglands • seminalvesicles • prostategland • bulbourethralglands • supportingstructures • penis

  4. Testis: GeneralOrganization • Tunica vaginalis – extension ofperitoneum • Tunica albuginea – dense CT layer • Mediastinum – projectionof the tunicaalbuginea • Lobules – formed fromsepta from the tunicaalbuginea

  5. SeminiferousTubules • General structure – 200-500 m inlength • Tunica propria – lamina propria surrounding the seminiferoustubules • Myoid cells – 3-5 layers thick, synthesize collagen, contractions help move sperm through thetubules • Basallamina • Seminiferous epithelium – complex stratified epithelium composed of spermatogenic cells and sertolicells

  6. Spermatogeniccells • Type A spermatogonia – ovoid nuclei, can be eithertype A dark (stem cells) or type A pale (committed tobecome sperm) • Type B spermatogonia – formed by mitotic division of type A pale cells, connected to each other by cytoplasmicbridges • Primary spermatocytes – result from the mitotic division of type B spermatogonia, large nuclei with dark staining condensedchromatin • Secondary spermatocytes – formed from the first meiotic division of primaryspermatocytes • Spermatids – formed following the second meiotic division • Spermatozoa – formed followingspermiogenesis

  7. Sertoli (Supporting)Cells • Structure • Long cytoplasmic processes extending between spermatogenic cells • Contain inclusion bodies ofCharcot-Böttcher • Functions • Blood-testis barrier – formed from unique tight junctions, separates sperm from immunesystem • Hormones – release inhibin, androgen bindingproteins • Respond to FSH andtestosterone • Support – support and nourish spermatocytes, therefore, also known as supporting or sustentacularcells • Other characteristics – do notreplicate

  8. LeydigCells • Structure • large, polygonal,acidophilic • Contain lipid droplets & Reinkecrystals • Location – interstitium of seminiferoustubules • Function – secrete testosterone in response toLH • Do notreplicate • Produce testosterone during early fetal life but are inactive untilpuberty

  9. Spermatogenesis • Note: during spermatogenesis, the developing sperm are connected to each other by cytoplasmic bridges. This ensures synchronous development of eachclone • Spermatogonial phase(mitosis) • Type A darkm→itosisType A palemi→tosisType A palem→itosisType Bm→itosis primaryspermatocytes • Spermatocyte phase(meiosis) • Meiosis I – primary spermatocyte forms two secondary spermatocytes (separation ofchromosomes) • Meiosis II – secondary spermatocyte forms two spermatids containing haploid DNA (separation ofchromatids)

  10. Spermiogenesis • there are four phases: • Golgiphase • Proacrosomal granules – contain glycoproteins (enzymes); granules fuse to form the acrosomalvesicle • Acrosomal vesicle – located near the nuclear membrane; its location determines the anterior pole of the developingsperm • Axonal complex – migration of centrioles to the posterior pole to initiate synthesis of axonemal complex of spermtail • Cap phase • Acrosomal cap – acrosomal vesicle condenses and covers the anterior half ofnucleus • Acrosome phase • Reorientation of spermatid with head pointed down into Sertolicell • Lengthening offlagellum • Manchette – organization of cytoplasmicmicrotubules • Centrioles migrate back to nucleus to initiate formation of the neck region • Maturation phase • Residual body – excess cytoplasm is pinched off and phagocytized by Sertolicells

  11. Structureofa Mature Sperm • Head – nucleus & acrosomalcap • Neck – centriole, excess nuclear envelop, striated columns • Tail • Middle piece – 9 outer doublets, central doublet of MTs, 9 outer dense fibers, mitochonderialsheath • Principle piece – outer dense fibers gradually decrease in number and are surrounded by a fibroussheath • Tail end piece – microtubules, no densefibers

  12. IntratesticularDucts • Straight Tubules (Tubulirecti) • Location – immediately after seminiferoustubule • Epithelial lining – Sertoli cells only at junction with seminiferous tubules becoming simple cuboidal near retetestis • Function – transport ofsperm • Rete Testis • Location – interconnecting within CT ofmediastinum • Epithelial lining – simple cuboidal to lowcolumnar • Function –transport • EfferentDuctules • Location – rete testis connects to 20 efferentductules • Epithelial lining – pseudostratified columnar (sawtooth appearancedue to presence of tall ciliated columnar cells used for moving sperm and low columnar cells with microvilli used for fluid absorption; basal cells are alsopresent) • Muscle layer – first appearance of a layer of smooth muscle; elastic fibers are interspersed among the musclecells • Function – transport ofsperm

  13. Ductusepididymus • Efferent ductules coalesce to form a single ductus epididymis Structure– highly coiled; 4-6 mlong • Divisions – head, body,tail • Tail is the principle reservoir of maturesperm • Epithelium – pseudostratified columnar withstereocilia • Muscular layer – graduallythickens • the tail has three layers: inner and outer longitudinal and middle circular layer. • The muscle of the head and body move sperm by peristaltic contraction; sperm is ejected during ejaculation by muscle of thetail • Function • Sperm reservoir (tailregion) • Fluid absorption and phagocytosis of remaining residual bodies and damaged sperm • Secretion • Further development of sperm – addition of surface glycosides to inhibit sperm binding toegg • Ejection of sperm duringejaculation

  14. Vasdeferens • Structure • Epithelium – pseudostratified columnar withmicrovilli • Three muscle layers – inner & outer longitudinal, middlecircular • Ampulla – enlargement of the distal end where it is joined by the duct of the seminalvesicle • Functions – secretory;transport Ejaculatoryducts • Structure – continuation of the vas deferens through the prostategland • Epithelium - pseudostratified columnar withmicrovilli • Other features– • NO muscle layers except fibromuscular tissue of theprostate • Empties into the prostaticurethra • Functions – secretory;transport

  15. vasdeferens Epididymis

  16. SeminalVesicles • Structure • One primary lumen; numerous primary and secondary folds that increase surface area • Pseudostratified columnarepithelium • Inner circular and outer longitudinal muscle layers which contracts during emission adding stored secretions to seminalfluid • Function • produces and secretes 60% of the volume ofsemen • secretion is viscous, whitish-yellow containing fructose, simple sugars, ascorbic acid, amino acids and prostaglandins. • Secretion requirestestosterone

  17. ProstateGland • Structure– • Consists of 30-50 tubuloalveolarglands • lined with pseudostratified or simple columnarepithelium. • The glandular components are arranged in threelayers: • Mucosal layer (central zone) – empty directly in theurethra • Submucosal layer (transition zone) – glands empty first into the prostatic sinus and then into theurethra • Peripheral layer (peripheral zone) – the main prostatic glands, empty into prostatic sinuses • Prostatic concretions (corpora amylacea) – precipitated secretory material that may be calcified, found in alveoli particularly in oldermen • Capsule – fibroelastic CT and smooth muscle, contracts duringemission • Function– produces 30% of semenvolume. • Secretion is milky fluid containing citric acid, cholesterol, acid phosphatase, fibrinolysin, andelectrolytes • Benign prostatic hypertrophy (BPH) &cancer • BPH normally occurs in older men in the mucosal and submucosalglands • malignancies occur in the epithelium of the main peripheralglands

  18. BulbourethralGlands • Structure – tubuloalveolar, mucus secretory glands lined with simple columnarepithelium • – Surrounded by intermixed smooth & skeletalmuscle • Function – secretes preseminal fluid that lubricates the penile urethra prior toejaculation • Glands of Littre (urethralglands) • Structure – predominantly around penileurethra • Function – mucus secretion protectsepithelium from urine

  19. Penis • Structure • Erectile tissue – three cavernous bodies surrounded by loose elastic connective tissue with an outer covering of thinskin • skin extends over the glans penis (prepuce or foreskin) unless removed by circumcision. • A thick fibrous sheath called the tunica alboginea surrounds each cavernousbody. • The cavernous bodies consist of irregular vascular spaces separated by trabeculae of dense fibroelastictissue. • The 3 bodiesare: • Corpora cavernosa – two dorsal erectile tissues of thepenis • Corpus spongiosum (corpus cavernosum urethrae) – ventral erectile tissue, surroundsurethra

  20. Erection • Results from parasympathetic postganglionic efferent impulses which cause penile arteries to dilate, more blood enters cavernous spaces, cavernous body distends compressing veins, engorgement results inerection • arterial dilation also mediated by nitric oxide produced by endothelial cells • Note: Viagra enhances the effects of nitric oxide resulting in vasodilation • Emission • Results from adrenergic (sympathetic)stimulation • stimulation causes movement of sperm from the tail of the epididymis and contractions of the vas deferens, seminal vesicle and prostate gland • Ejaculation • Results from contraction of skeletal muscle surrounding the corpora cavernosa (the ischiocavernosis) and the corpus spongiosum (the bulbospongiosus) • muscle contraction ejects semen out of theurethra

More Related