22 [0-0]: [12-1]: H & E- In the adult male spermatozoa are produced within seminiferous tubules of the testis (a), which empty into cavities of the rete testis (b) continuous with the ductuli efferentes (d) which in turn are continuous with the ductus epididymidis (c). [12-2]: H & E- In this cross section of a seminiferous tubule can be observed the seminiferous epithelium containing germ cells and Sertoli cells. [12-3]: H & E- Within the seminiferous epithelium only the Sertoli cells (arrows) extend from the basement membrane to the lumen. Generally, only the Sertoli cell nuclei are readily distinguishable from the surrounding germ cells. The Sertoli cell nuclei are typically oval to pyramidal in shape, contain a prominent nucleolus and an infolding of the nuclear plasma membrane. Note the elongating spermatids adjacent the luminal surface. [12-4]: TEM 18-1- Within the seminiferous epithelium can be observed 1. spermatogonia, 2. a typically darker staining Sertoli cell, 3. round spermatids, 4. Golgi complex, 5. mitochondria, and 6. the heads of elongated spermatids. [12-5]: TEM 18-2- In this section of a seminiferous tubule can be observed the 1. basement membrane, 2. spermatogonia, 3. a typically darker staining Sertoli cell, 4. mitochondria, 5. nucleus of a round spermatid, 6. the head of an elongating spermatid, 7. another round spermatid, and 8. the Golgi apparatus adjacent an acrosomal vesicle. [12-6]: TEM 18-5- Elongating spermatids exhibit 1. an acrosome, 2. a condensed nucleus, 3. a connecting piece, continuous with the mid-piece containing 4. an axoneme, 5. surrounded by mitochondria, connected to 6. the principal piece, which contains circumferential fibers, connected to the 8. end piece. [12-7]: H & E- Between the seminiferous tubules occur clusters of Leydig (interstitial) cells which tend to stain darkly with eosin and exhibit round nuclei. Question- What major steroid is secreted by the Leydig cells? Answer- Testosterone [12-8]: TEM 18-3 In this section of a seminiferous tubule containing spermatogonia (3) the basement membrane (1) occurs adjacent to a peritubular myoid cell (2). In the interstitial space occurs a capillary (4) lined by endothelial cells (5) and abundant Leydig (interstitial) cells (6). Question- Which pituitary hormone regulates Leydig cell steroidogenesis. Answer- Luteinizing Hormone. [12-9]: Trypan blue. The epididymis (ductus epididymidis) is lined by a pseudostratified columnar epithelium with stereocilia projecting into the lumen. [12-10]: TEM 18-4- Principal cells lining the epididymal duct exhibit 1. sterocilia, 2. terminal bar, 3. Golgi apparatus, 4. nucleus, 5. mitochondria. [12-11]: H & E- The ductus (vas) deferens is continuous with the cauda epididymis and is similarly lined with a pseudostratified columnar epithelium. As the ductus deferens extends away from the epididymis the lining epithelium becomes increasingly folded. Surrounding the lining epithelium is three layers of smooth muscle (inner longitudinal, middle circular, outer longitudinal). [12-12]: H & E- At the terminal end of the ductus deferens the duct widens and the pseudostratified columnar epithelium becomes highly folded to form the ampulla. [12-13]: H & E- The seminal vesicles contain highly folded epithelium. [12-14]: H & E- The highly folded epithelium of the seminal vesicles is enclosed within a lamina propria, and a muscularis of inner circular and outer longitudinal smooth muscle continuous with an adventitia. [12-15]: H & E- The mucosal folds of the seminal vesicles are lined with either simple columnar and/or pseudostratified columnar epithelium. [12-16]: H & E- The prostate gland is a chestnut shaped organ enclosed in a connective tissue capsule. [12-17]: H & E- The compound tubuloalveolar prostate gland is lined by simple and/or pseudostratified columnar epithelium. Each acini is surrounded by stroma consisting of abundant smooth muscle. Prostatic secretions often form concretions called corpora amylacea (a). [12-18]: H & E- The bulbourethral glands (Cowpers gland) empty into the base of the penis. These tubulo- alveolar glands secrete a mucous sialoglycoprotein. The surrounding stromal tissue contains both smooth muscle and skeletal muscle. [12-19]: H & E- The urethra extends from the bladder to the glans penis. The urethra is divided into three parts. The first part is called the prostatic urethra as shown in this slide. The prostatic urethra is lined by a transitional epithelium. [12-20]: H & E- The second and third parts of the urethra are called the membranous and penile urethra, respectively. Both the membranous and penile urethra can be lined by stratified columnar (as shown here) or pseudostratified columnar epithelium. [12-21]: H & E. The penis consists of a corpus spongiosum surrounding the penile urethra, and a pair of corpus cavernosa surrounded by a thick tunica albuginea of connective tissue.