histo recap

• Testis


  Exocrine and endocrine in nature. Produce cellular secretory product in form of sperm and testosterone as a true endocrine secretion.

  
• Tunica vaginalis


  • Mesothelium and connective tissue layer that blends with underlying connective tissue of scrotum and testis. A space, vaginal cavity, separates parietal and visceral layers.
• Tunica albuginea


  • Outer border of testis, a thick band of dense collagenous connective tissue with many blood vessels running through it, including some testicular artery and a network of anastomosing veins that form vascular layer.
• Interstitial Leydig cells


  Produce male steroid hormone: testosterone. Located in regions between seminiferous tubules in loose connective tissue, with many capillaries, lymph vessels, and fibrocytes.
• Seminiferous tubules


  • Bulk of testicular tissue, designed for massive production of sperm. Lined by stratified spermatogenic epithelium surrounded by lamina propria.
• Lamina propria


  • Innermost layer is a basement membrane. Collagen and elastic fibers connect basement membrane to myoid cells or peritubular contractile cells.
• Sertoli or sustentacular cells


  Supporting cells that sustain proper environment for spermatozoa development.
• Intratesticular ducts


  Straight tubules and rete testis carry spermatozoa and liquid from seminiferous tubules to duct of epididymis.
• Rete testis


  • Labyrinth-like structure placed in mediastinum testis, lined with groups of nonciliated cuboidal cells alternating with groups of taller ciliated cells. Absorption and ciliary activity create a fluid flow that carries sperm out of testis toward epididymis.
• Efferent ducts


  • Relatively short and highly coiled ducts lined by a pseudostratified columnar epithelium, many of the cells are ciliated.
• Epididymis


  • Receives input of sperm from efferent ducts and acts as a storage and maturation facility for them. Lined with a pseudostratified columnar epithelium with large microvilli (stereocillia) consisting of columnar principal cells and small round stem cells.

  
• Ductus deferens


  • Conveys spermatozoa from tail of epididymis to ejaculatory duct. Mucosal lining is thrown up into longitudinal folds, lined by a stereociliated pseudostratified columnar epithelium placed on a basal lamina surrounded by connective tissue and smooth muscle fibers.

  
• Spermatic cord


  • Carries the principal artery (testicular artery) supplying blood to the organ and veins that drain it. Veins and arteries lie side by side, allowing the blood moving through arteries to be cooled slightly. Also contains the cremaster muscle.
• Seminal vesicles


  • Highly coiled tubes, each about 15 cm long in men, enclosed by a connective tissue capsule. Mucosa displays a great number of thin folds, glandular epithelium is pseudostratified with tall columnar cells and basal cells.
• Prostate


  • Varying number of individual tubuloalveolar glands embedded in a dense fibromuscular stroma, arranged in three major zones around the urethra: transition zone, central zone, and peripheral zone.
• Bulbourethral gland


  • Dorsolateral to penile portion of urethra, secretory portions are lined with simple columnar epithelium and few basal cells, sheathed by a fibroelastic capsule containing striated muscle fibres.

  
• Penis


  • Three cylindrical masses of erectile tissue, two dorsal corpora cavernosa and one ventral corpus spongiosum that surrounds the urethra. Glans penis is covered by prepuce or foreskin.
• Os penis is a triangular shaped bone located dorsal to the urethra and ventral to the corpus cavernosum, found in carnivores.
• Renal corpuscle


  • Structural and functional unit of the kidney, can be classified by location of their glomeruli in the cortex as superficial, midcortical, or juxtamedullary.

  
• Proximal tubule


  • Begins at the urinary pole of the renal corpuscle, first portion is the proximal convoluted tubule with a brush border, then becomes the proximal straight tubule.
• Loop of Henle


  • Includes four tubule segments: descending thick limb, descending thin limb, ascending thin limb, and thick ascending limb. Made of simple squamous epithelium with a thin outer wall and empty lumen.
• Distal tubule


  • Simple cuboidal epithelium that lacks a brush border, role is to pump sodium ions out of its lumen into the surrounding intercellular space.
• Juxtaglomerular apparatus


  • Association between a distal tubule and its own corpuscle, involved in regulation of systemic blood pressure. Includes juxtaglomerular cells that are modified smooth muscle cells with renin granules, and macula densa cells that may function as chemoreceptors.

  
• Connecting segment


  • Epithelium contains a variety of cell types, marks the terminus of the nephron but modification isn't finished as it passes through the cortical gradient a second time in the collecting tubules and collecting ducts.
• Collecting tubules and collecting ducts

  • Collecting tubules have walls formed of cuboidal epithelium, larger than the distal tubule. Collecting ducts have a distinctly high cuboidal to columnar epithelium, formed by fusion of multiple collecting tubules.
• Renal cortex


  • Darker red outer region with a large number of renal corpuscles and various types of renal tubules.
• Renal medulla


  • Lighter inner region with no renal corpuscles, only tubules that appear striated and radiate from the medulla.
• Ureter


  • Epithelium rests on a basal lamina with a support of connective tissue, has a muscular wall made from two layers of smooth muscle cells.
• Urinary bladder


  • Wall has three layers of smooth muscle, lined by urinary epithelium that is extensively folded in the relaxed state.
• Urethra


  • In women, exclusively a urinary organ lined with transitional epithelium then stratified squamous epithelium. In men, the urethra is longer and consists of three segments: prostatic urethra, membranous urethra, and penile urethra.
• Urine passing through urinary tube

  Lumen of tube dilates under pressure
• Urinary bladder


  Temporary storage organ for urine
• Urinary bladder wall


  • Similar to ureter, but has 3 layers of smooth muscle: inner and outer longitudinal, middle more or less circular
  • Contains a fair amount of elastic connective tissue to provide for elasticity and distensibility
• Urinary bladder lining


  Urinary epithelium, extensively folded in relaxed state
• Inclusion bodies characteristic of urinary epithelial cells are evident
• Urethra


  Tube that carries urine from bladder to exterior
• Female urethra


  • Exclusively a urinary organ, lined initially with transitional epithelium then by stratified squamous epithelium
• Male urethra


  • Longer and consists of 3 segments: prostatic urethra (lined by urothelium), membranous urethra (lined by stratified columnar and pseudostratified epithelium), spongy urethra (lined by stratified squamous epithelium distally)
• Kidney is a place in which blood is filtered
• Blood flow is the driving force behind urine formation