Major function of testes
Produce male gametes or spermatozoa and androgens
Male excurrent ducts
Ductuli efferentes, ductus epididymidis, ductus vas deferens
Male accessory sex glands
Seminal vesicle, prostate, bulbourethral glands
Outer dense connective tissue of the testis
Tunica albuginea
Inner layer of the testis capsule
Tunica vasculosa
Posterior surface of the tunica albuginea that thickens and projects inward
Mediastinum testis
Spaces between seminiferous tubules
Testicular interstitium
Steriod-producing endocrine cells located in the testicular interstitium
Leydig cells
Cell structure of Leydig cells
Well-developed SER, mitochondria with tubular cristae, numerous lipid droplets, crystals of Reinke on electron microscope
Functions of Leydig Cells
Main source of testosterone
Cells of the seminiferous epithelium
Sertoli cells and spermatogenic cells
Composition of the tunica propria of the seminiferous tubules
Fibroblasts and collagen fibrils
Support cells of the seminiferous epithelium
Sertoli cells and spermatogenic cells
Appearance of the Sertoli cells
Large, irregular, very light-staining euchromatic nucleus with well-expressed nucleolus
What is unique about the Sertoli cell junctions
Both tight and adherence junctions that can be disassembled and reassembled under certain factors
How do the Sertoli cells help germ cells?
Nourish, participate in cell movement and differentiation
Divisions that the Sertoli cells make
Basal and adluminal compartments
Barrier between blood and maturing sperm cells
Blood-testis barrier made by the Sertoli cells
What is the effect of the blood-testis barrier?
Immunologically privileged site, which limits/suppresses the immune response here
What do the Sertoli cells secrete?
Androgen-binding proteins and inhibin
Binds testosterone and is used to maintain the high testosterone concentration in the seminiferous tubules
Androgen-binding proteins
Secreted by Sertoli cells to inhibit FSH by the pituitary
Inhibin
What happens to residual bodies and dengerated germ cells within the seminiferous epithelium?
Sertoli cells phagocytize them
Hormonal regulation of Sertoli cells
Testosterone produced by Leydig cells and FSH produced by pituitary glands
Cells that replicate and differentiate into mature sperm
Spermatogenic cells (germ cells)
How are germ cells organized within the seminiferous epithelium?
Most immature stages are located closer to the tunica propria, more mature cells move into the adluminal compartment
Initial stage of development of the sperm
Spermatogonial phase
3 Types of spermatogonia cells
Type A dark, Type A pale, Type B
Describe type A dark spermatogonia
Ovoid nuclei with basophilic dark granular chromatin
Describe type A pale spermatogonia
Ovoid nuclei with lightly-staining fine granular chromatin, derived from from Ad cells
How are type B spermatogonia cells formed?
Type A pale undergo mitosis to differentiate into type B
Describe type B spermatogonia
Spherical nuclei with chromatin condensed into large clumps
Most mature spermatogonia
Type B
Phase in which spermatocytes undergo meiosis
Spermatocyte phase
Describe spermatocytes
Round nucleus
Derived from type B spermatogonia. Get arrested in prophase I of the 1st division of meiosis
Primary spermatocytes
Spermatocytes in meiosis II
Secondary spermatocytes
Haploids formed from meiotic divisions of secondary spermatocytes
Spermatids
Phase in which extensive cell remodeling occurs when spermatids differentiate into mature sperm
Spermatid phase
Stages of spermatid remodeling
Golgi phase, cap phase, Acrosome phase, Maturation phase
Describe the Golgi phase
Accumulation of numerous proacrosomal granules that start to become a larger acrosomal vesicle, centrioles migrate to the posterior pole to form the axoneme
Central core of the sperm tail with 9 peripheral doublets
Axoneme
Describe the Cap phase
Acrosomal vesicles spreads around the nucleus to form the acrosomal cap
Describe the acrosome phase
Spermatid changes its orientation so that the head is embedded into the Sertoli call, developing flagellum is pointed towards the lumen
How does the germ cell change during the acrosome phase?
Cell/nucleus becomes more elongated and nucleus flattens; nucleus and acrosomal cap migrate anteriorly; manchette is formed; neck region is formed; mitochondria migrate posteriorly to form the middle piece of the tail; manchette disappears
Cytoplasmic microtubules that form a cylindrical sheath in the changing germ cell
Manchette
Connects the nucleus to the flagellum
Neck region
Describe the maturation stage
Excessive sytoplasm is removed to form residual bodies (consumed by Sertoli cells) cytoplasmic bridges b/t the spermatids are broken and individual spermatids are liberated from the system
Parts of a sperm
head, neck, tail
Lysosome-like organelle that contains enzymes secreted during fertilization in order to digest an opening in the zona pellucida of the ovum
Acrosome
Short, narrow area where the centrioles are located
Neck region
Contains axoneme and associated structures
Tail
3 segments of the tail
Middle piece, prinicpal piece, end piece
Describe the middle piece
Contains spiral mitochondria wrapped around the outer dense fibers that surround the axoneme
Longest segment of the tail containing the axoneme covered with outer dense fibers
Principal piece
Portion of the tail that is not covered with outer dense fibers
End piece
Important factor that influences spermatogenesis
Testicular temperature is kept at 35degrees C due to the pampiniform plexus
Where do sperm go after they are formed?
Straight tubules (tubuli recti)
Cells of the rete testis
Ducts lined with simple cubodial epithelium
3 External male genital ducts
Ductuli efferentes, ductus epididymidis, ductus vas deferens
Cresent shaped organ that lies along the superior and posterior surface of the testis, prinicple site of sperm maturation
Epididymis
Highly coiled tubules that connect rete testis to the ductus epididymidis
Ductuli efferentes
Cells of the ductuli efferentes
Low, pseudostratified columnar epithilium with both cilitated and non-ciliated cells, gives a saw tooth appearance
Composition of the ductus epididymidis
Highly coiled tube that contains smooth muscle and connective tissue with associated vessels in its walls
Cells of the ductus epididymidis
Tall pseudostratified columnar epithelium with stereocilia
The continuation of the tail of the epididymis, straight tube that continues from the epididymus to the prostatic urethra
Ductus vas deferens
Lines the mucosa of the vas deferens
Pseudostratified columnar epithelium with deep longitudinal folds
Layers of the ductuc vas deferens
Mucosa, muscularis, adventitia
Paired elongated tubular glands, that opens into the ampulla of the vas deferens
Seminal vesicles
Parts of the seminal vesicle
Mucosa, lamina propria, muscularis, fibrous coat
What are the cells of the seminal vesicle mucosa rich in?
Secretory granules
What do the secretory granules of the seminal vesicle cells contain?
Spermatozoa-activating substances: carbohydrates(mostly fructose), prostaglandins, several proteins
Largest accessory sex gland in the male
Prostate
Surrounds the prostate
Fibrocollagenous connective tissue capsule that contains smooth muscle fibers
Type of cells in the tubuloalveolar glands of the prostate
Low columnar/cuboidal pseudostratified epithelium
Zones of prostatic gland
Transitional zone, peripheral zone
Contains the mucosal layer of glands and is located near the prostatic urethra
Transitional zone
Contains the main prostatic glands
Peripheral zone
What does the stroma of the prostate consist of?
Fibroblasts, collagen fibers, smooth muscle fibers
Spherical concretions composed of what are often found in the lumen of the tubuloalveolar glands?
Corpora amylacea
Secretions of the prostate
Acid phosphate, citric acid, fibrinolysis
Decrease in testosterone does what to the prostate?
Maintain structural and functional integrity, maintain secretory activity
Significant enlargement of the glands of the transitional zone
Begnign prostatic hyperplasia
Where does prostate cancer almost always originate?
Peripheral zone
Describe the bulbourethral glands
Compound tubuloalveolar glands that are mucus-secreting (for lubrication)
2 dorsal cylinders of the penis
Corpora cavernosa
Ventral cylinder of the penis
Corpus spongiosum
Surrounds the cylinders and holds them together
Tunica albuginea
Fill with blood during an erection
Vascular spaces
Mucus secreting glands of the corpus spongiosum
Glands of Littre
Unique aspect of the skin of the penis
Loose subcutis
Overlap of the penile skin
Prepuce
Where does the erectile tissue receive the majority of its blood?
Helicine arteries
What happens in response to GnRH?
Gonadotropes produce LH that acts on the Leydig cells and FSH that acts on Sertoli cells
What do Leydig cells produce
Testosterone
What hormone do Sertoli cells produce?
Androgen-binding proteins and inhibin