Male Reproductive Tract Histology PDF

Histology of the Male Reproductive Tract [email protected] @orientatewithjoyce Lecture Outline - Male reproductive system overview - Histology of the testes - Histology of the epididymis and vas deferens - Histology of the seminal vesicle and prostate LEARNING OUTCOMES: LO1: To understan...

Histology of the Male Reproductive Tract [email protected] @orientatewithjoyce Lecture Outline - Male reproductive system overview - Histology of the testes - Histology of the epididymis and vas deferens - Histology of the seminal vesicle and prostate LEARNING OUTCOMES: LO1: To understand and identify the basic components of male reproductive system LO2: To understand and describe the histological features of testis LO3: To identify cells of the germinal epithelium of the seminiferous tubule: Sertoli cells, spermatogonia, spermatocytes, spermatids and spermatozoa LO4: To understand and identify the structural features of epididymis and vas deferens LO5: To understand and the seminal vesicle, and prostate Overview of male reproductive system Three key functions of this system are production of spermatozoa, delivery of these cells via semen and production of testosterone TESTES Testes – Overview Schematic of tubules and ducts. Vas deferens • • • Ovid gland that sits within the scrotum After spermatozoa are produced in the testes, they travel a long, tortuous route: from seminiferous tubules to the paired rete testis, efferent ductules (ductuli efferenti), epididymis, ductus (vas) deferens. Encased in a thick capsule of dense fibroelastic CT known as tunica albuginea (white) Seminiferous tubules Efferent ductules Rete testis Tubulu recti Lobule Epididymis Epididymis TA Tunica albuginea Testis Vas deferens Light micrograph (LM) of part of the testis at low magnification. A thick capsule—the tunica albuginea (TA)—covers it externally. Parts of the ductus Tunica a LM of a seminiferous tubule in transverse section. A capsule (arrows) surrounds seminiferous epithelium. Spermatogonia (Sg) are at the tubule base; large spermatocytes (Sp) and smaller spermatids (S) are closer to the lumen. Pillar-shaped Sertoli cells (SC) are interspersed with germ cells. A clump of Leydig cells is in adjacent stroma. 450×. H&E. Testes - Seminiferous Tubules - Surrounded by a CT capsule with myoid cells SC Leydig cells Seminiferous tubule Epithelium is stratified epithelium with 2 types of cells: S 1. Spermatogenic cells (germ cells) Sp Sg 2. Sertoli cells 17.4 HISTOLOGY OF SEMINIFEROUS TUBULES A distinct connective tissue capsule, a layer of flattened myoid cells, and a basement membrane surround seminiferous tubules. The seminiferous epithelium is an unusual, complex stratified epithelium with two cell populations: spermatogenic (or germ) cells and nonproliferating Sertoli cells. In a seminiferous tubule, germ cells are at various stages of spermatogenesis. The cells closest to the basement membrane with spherical nuclei are spermatogonia. Larger cells with spherical nuclei but with distinctive Ch017-NB86.indd 381 spaghetti-like chromatin are primary spermatocytes. The haploid secondary spermatocytes are seldom seen; almost as soon as they form they divide and produce spermatids. During a transformation period, spermatids attach to the relatively few Sertoli cells, which are tall and pillar-like. The bases of the Sertoli cells rest on the basement membrane; the free ends of the cells extend radially and reach the lumen. Spermatids, which are known as early and late, do not divide but mature into spermatozoa, which are released into the lumen and carried into efferent ducts. 7/3/2007 11:18 Testes – Spermatogenic cells - The cells closest to the Basement membrane are spermatogonia LM of a seminiferous tubule in transverse section. A capsule (arrows) surrounds seminiferous epithelium. Spermatogonia (Sg) are at the tubule base; large spermatocytes (Sp) and smaller spermatids (S) are closer to the lumen. Pillar-shaped Sertoli cells (SC) are interspersed with germ cells. A clump of Leydig cells is in adjacent stroma. 450×. H&E. SC Leydig cells Seminiferous tubule S - Larger cells with spherical nuclei are primary and secondary spermatocytes Sp Sg - Spermatocytes produce spermatids - Spermatids mature into spermatozoa which are released into the lumen 17.4 HISTOLOGY OF SEMINIFEROUS TUBULES A distinct connective tissue capsule, a layer of flattened myoid cells, and a basement membrane surround seminiferous tubules. The seminiferous epithelium is an unusual, complex stratified epithelium with two cell populations: spermatogenic (or germ) cells and nonproliferating Sertoli cells. In a seminiferous tubule, germ cells are at various stages of spermatogenesis. The cells closest to the basement membrane with spherical nuclei are spermatogonia. Larger cells with spherical nuclei but with distinctive Ch017-NB86.indd 381 spaghetti-like chromatin are primary spermatocytes. The haploid secondary spermatocytes are seldom seen; almost as soon as they form they divide and produce spermatids. During a transformation period, spermatids attach to the relatively few Sertoli cells, which are tall and pillar-like. The bases of the Sertoli cells rest on the basement membrane; the free ends of the cells extend radially and reach the lumen. Spermatids, which are known as early and late, do not divide but mature into spermatozoa, which are released into the lumen and carried into efferent ducts. 7/3/2007 11:18 Testes – Spermatogenic cells • At puberty: primitive germ cells – spermatogonia – enlarge and become mitotically active and undergo spermatogenesis. • This gives rise to spermatozoa. • During differentiation, spermatozoa move towards the lumen. • This process takes about 64-74 days, is coordinated by Sertoli cells and continues throughout life. YOU DO NOT NEED TO KNOW SPERMATOGENESIS IN DETAIL – YOU DO NEED TO KNOW THE CELLS AND WHERE THEY ARE FOUND HISTOLOGICALLY - - - Testes – SERTOLI CELLS Sertoli (sustentacular) cells phagocytose spermatid remnants and secrete fluid and many substances, including androgen- binding protein (ABP), essential for spermatozoa survival. LM of a seminiferous tubule in transverse section. A capsule (arrows) surrounds seminiferous epithelium. Spermatogonia (Sg) are at the tubule base; large spermatocytes (Sp) and smaller spermatids (S) are closer to the lumen. Pillar-shaped Sertoli cells (SC) are interspersed with germ cells. A clump of Leydig cells is in adjacent stroma. 450×. H&E. Leydig cells Seminiferous tubule S This protein binds testosterone and helps maintain a high concentration of testosterone within the testes. Histologically, Sertoli cells are tall and pillar-like. The bases of the Sertoli cells rest on the basement membrane; the free ends of the cells extend radially and reach the lumen. SC Sp Sg 17.4 HISTOLOGY OF SEMINIFEROUS TUBULES A distinct connective tissue capsule, a layer of flattened myoid cells, and a basement membrane surround seminiferous tubules. The seminiferous epithelium is an unusual, complex stratified epithelium with two cell populations: spermatogenic (or germ) cells and nonproliferating Sertoli cells. In a seminiferous tubule, germ cells are at various stages of spermatogenesis. The cells closest to the basement membrane with spherical nuclei are spermatogonia. Larger cells with spherical nuclei but with distinctive Ch017-NB86.indd 381 spaghetti-like chromatin are primary spermatocytes. The haploid secondary spermatocytes are seldom seen; almost as soon as they form they divide and produce spermatids. During a transformation period, spermatids attach to the relatively few Sertoli cells, which are tall and pillar-like. The bases of the Sertoli cells rest on the basement membrane; the free ends of the cells extend radially and reach the lumen. Spermatids, which are known as early and late, do not divide but mature into spermatozoa, which are released into the lumen and carried into efferent ducts. 7/3/2007 11:18 - - - Testes – Intratubular space LM of a seminiferous tubule in transverse section. A capsule (arrows) surrounds seminiferous epithelium. Spermatogonia (Sg) are at the tubule base; large spermatocytes (Sp) and smaller spermatids (S) are closer to the lumen. Pillar-shaped Sertoli cells (SC) are interspersed with germ cells. A clump of Leydig cells is in adjacent stroma. 450×. H&E. Contains CT and Leydig (interstitial) cells Clusters of eosinophilic Leydig (interstitial) cells Leydig cells Seminiferous tubule S Sp Sg 386 Male Reproductive System 17.4 HISTOLOGY OF SEMINIFEROUS TUBULES A distinct connective tissue capsule, a layer of flattened myoid cells, and a basement membrane surround seminiferous tubules. The seminiferous epithelium is an unusual, complex stratified epithelium with two cell populations: spermatogenic (or germ) cells and nonproliferating Sertoli cells. In a seminiferous tubule, germ cells are at various stages of spermatogenesis. The cells closest to the basement membrane with spherical nuclei are spermatogonia. Larger cells with spherical nuclei but with distinctive The Leydig cells have a foamy, washedout cytoplasm is due to high lipid content, as they store cholesterol for synthesis of testosterone. These large polyhedral cells have an eccentric spherical nucleus with one or two prominent nucleoli, and cell surfaces have numerous small microvilli. SC Ch017-NB86.indd 381 spaghetti-like chromatin are primary spermatocytes. The haploid secondary spermatocytes are seldom seen; almost as soon as they form they divide and produce spermatids. During a transformation period, spermatids attach to the relatively few Sertoli cells, which are tall and pillar-like. The bases of the Sertoli cells rest on the basement membrane; the free ends of the cells extend radially and reach the lumen. Spermatids, which are known as early and late, do not divide but mature into spermatozoa, which are released into the lumen and carried into efferent ducts. ST 7/3/2007 11:18:15 AM Cap Leydig cells ST ST LM eosin intima to out 625× EPIDIDYMIS EPIDIDYMIS • Includes head, body, and tail • Responsible for transmitting spermatozoa from the rete testes to the vas deferens EPIDIDYMIS - The epididymal ducts consists of pseudostra*fied epithelium containing basal cells and tall columnar (principal) cells with long, apical, nonmo:le stereocilia projec:ng into the lumen. - Stereocilia amplify the cell surface area and func:on in absorp:on of excess fluid that accompanies spermatozoa from the tes:s. - In transit, spermatozoa mature and acquire mo:lity and fer:lizing capacity. - Loose connec:ve :ssue and some circularly arranged smooth muscle are also found outside the ducts. - The smooth muscle in the head of the epididymis undergoes spontaneous peristal:c contrac:ons. Epididymal duct Male Reproductive System 389 LM of the duct of the epididymis in transverse section. The wall consists of tall pseudostratified epithelium of uniform thickness with apical nonmotile stereocilia. Spermatozoa are in the lumen. Surrounding lamina propria is loose, richly vascular connective tissue. The rectangle indicates an area similar to that seen below. 320×. H&E. High-magnification LM of the epithelium of the epididymis. The two major cell types of the epithelium rest on a basement membrane. Tall columnar cells have elongated, euchromatic nuclei and long, apical stereocilia. Small, round basal cells (arrows) on the basement membrane do not reach the luminal surface. They are most likely germinative stem cells for the epithelium. Underlying fibrous connective tissue contains smooth muscle. 525×. H&E. Stereocilia Lumen DUCTUS (VAS) DEFERENS DUCTUS (VAS) DEFERENS A long straight tube joins with duct of seminal vesicle to form ejaculatory duct which opens in prostatic urethra 390 Male Reproductive System Mucosa DUCTUS (VAS) DEFERENS Lumen Consists of: o Mucosa; Muscularis Adventitia (some § Epithelium: pseudostratified epithelium cells have sparse stereocilia) § Lamina propria: contains many elastic Higher fibres magnification LM o Muscular wall: § Longitudinal inner layer § Middle circular layer § Longitudinal outer layer o Adventitia Muscularis LM of the ductus deferens in transverse section. Folds of mucosa produce a stellate lumen. Around the mucosa is a prominent three-layer coat of tightly spiraled smooth muscle, the muscularis. Blood vessels, nerves, and lymphatics travel through an adventitia of loose connective tissue that covers the ductus externally. 35×. H&E. Adventitia Lumen of the mucosa of the ductus deferens. The highly folded mucosa consists of pseudostratified columnar epithelium, which closely resembles that of the epididymis. Columnar cells with apical stereocilia and a row of small, round basal cells (arrows) are seen. The mucosal folds are due to contraction of underlying smooth muscle. 285×. H&E. Lamina propria Smooth muscle 17.13 HISTOLOGY OF THE DUCTUS (VAS) DEFERENS ductus is more than just a passive conduit for spermatozoa from epididymis to urethra; ultrastructural data suggest that it has both SEMINAL VESICLES Seminal vesicles - Production of semen Seminal fluid is important for semen coagulation, sperm motility, and stability of sperm chromatin and suppression of the immune activity in the female reproductive tract. Male Reproductive System 395 A (20X; H&E; Seminal vesicle) Seminal vesicles • • Arrows: mucosal folds L: lumen B (300X; H&E; Mucosal folds in seminal vesicle) • SM: smooth muscle • LP: lamina propria SM • Mucosa; containing a lot of folds composed of: § Epithelium: simple or pseudostratified columnar epithelial cells rich in LM of the seminal vesicle. The gland’s mucosal folds are complex, and its wall has smooth muscle (SM) secretory granules arranged tightly in inner circular and outer longitudinal Flocculent eosinophilic material fills the lumen. § Lamina propria; thin layer containing layers. 50×. H&E. contains elastic fibers • Muscular layer composed of smooth muscle: § Inner circular layer § Outer longitudinal layer • Adventitia BC Higher magnification LM of the mucosa of the seminal vesicle. The honeycombed mucosa has an epithelium (arrows) composed of columnar cells and basal cells. Semen consists of spermatozoa formed in germinal epithelium of the testis and seminal fluid, the components of which are secreted by the excretory duct sytem and accessory glands. Most of this fluid is produced in seminal vesicles. 280×. H&E. High-magnification LM of the mucosa of the seminal vesicle. The epithelium is usually pseudostratified, but it may be simple columnar in places. Its height varies with age, phase of secretion, and hormonal influence. Columnar cells with eosinophilic, dome-shaped apical cytoplasm (arrows) are normally interspersed with small rounded basal cells (BC). 500×. H&E. PROSTATE PROSTATE • Production of prostatic fluid that contains prostaglandins and prostate-specific antigen (PSA). PROSTATE • Consists of 30-50 tubuloacinar (prostatic glands) glands embedded in a dense fibromuscular stroma in which smooth muscle contracts during ejaculation § The prostatic glands are lined with simple or pseudostratified columnar epithelium • Presence of Small spherical concretions called corpora amylacea in the lumens of many prostatic tubuloacinar glands • Partially calcified and eosinophilic • Increase with age (20X; H&E; Prostate) • S: fibromuscular stroma • G: tubuloacinar glands (122X; H&E; A prostatic gland) • CA: corpus amylaceum • E: secretory epithelium • LP: lamina propria • M: smooth muscle (300X; Mallory trichrome; Corpus amylaceum) • CA: corpus amylaceum • LP: lamina propria PENIS PENIS Function of penis: urination and sexual intercourse. PENIS – HISTOLOGY Two dorsal corpora cavernosa • Each of them surrounded by tunica albuginea A ventral corpus spongiosum • Surrounds the penile urethra • At the end, expands and form the glans of penis § Covered by the prepuce or foreskin • Most of the penile urethra lined with pseudostratified columnar epithelium which become stratified squamous epithelium in glans (15X; H&E; Penis) • CS: corpus spongiosum • U: urethra • CC: corpora cavernosa • TA: tunica albuginea • V: blood vessels • S: skin PENIS – HISTOLOGY Erectile tissues; consist of: • Venous cavernous spaces § Lined with endothelium § Separated by trabeculae with smooth muscle and connective tissue continuous with the surrounding tunic (100X; H&E; Penile urethra) • CS: corpus spongiosum • PU: penile urethra • UG: urethral gland • CC: corpora cavernosa • TA: tunica albuginea • HA: helicine artery (200X; H&E; Erectile tissue) • TA: tunica albuginea • SM: smooth muscle • CS: corpus spaces • HA: helicine artery