Histology of the Testis and Excretory Ducts Flashcards
2 functions of the male reproductive system
- Elaboration of sex hormones
- Formation and delivery of the male gametes into the female reproductive tract
Primary function of the testis
Production of spermatozoa (male gamete)
Androgen-producing cell of the testis
Leydig cell
4 functions of androgens
- Embryo development of male fetus
- Initiation and maintenance of spermatozoa production
- Development of accessory organs and secondary sex characteristics
- Secretion of accessory glands
Capsule of connective tissue surrounding the testis
Tunica albuginea
Tubules contained in the lobules of the testis
Seminiferous tubules
End of the seminiferous tubules
Rete testis
What embeds the seminiferous tubules in the lobules of the testis?
Connective tissue stroma (interstitium)
Location of Leydig cells
Interstitium surrounding the seminiferous tubules
6 histological characteristics of Leydig cells
- Polyhedral
- Round, homogenous nuclei
- Triangular clusters
- Acidophilic
- Elaborate SER
- Large juxtanuclear Golgi apparatus
- Abundant mitochondria
- Peroxisomes
2 electron micrograph characteristics of steroid producing cells
- Lots of mitochondria
- Lots of SER
Hormone that stimulates Leydig cells to secrete androgens
LH
2 effects of Mullerian inhibiting substance (MIS)
- Implication in the regulation of steroidogenesis
- Mullerian duct regression
Contractile elements of the seminiferous tubules
Myoid cells
Function of myoid cells of the seminiferous tubules
Peristaltic movement to transport the currently immotile spermatozoa from the seminiferous tubule towards the rete testis
5 contents of the interestitium of the lumen of the testis
- Leydig cells
- Lymphatics
- Blood vessels
- Fibrocytes
- Macrophages
Function of macrophages in proximity to Leydig cells
Production of cytokines that can crosstalk with Leydig cells
Somatic cells of the seminiferous epithelium
Sertoli cells
7 functions of the Sertoli cell
- Supportive or sustentacular (structural support)
- Nurse cells (biochemical support)
- Formation of the Blood-Testis Barrier (tight junctions)
- Secrete lumincal fluids including several proteins, such as enzymes and transport proteins
- Secrete hormones and factors
- Endocytic (receptor-mediated endocytosis) and phagocytic function
- Serve as lifts displacing the early spermatocytes from the basal compartment to the adluminal compartment (so blood-testis barrier is not disrupted)
How are Leydig cells able to renew their cytoplasm
Autophagocytosis
Enzymes secreted by Sertoli cells
Proteases
3 types of transport proteins secreted by Sertoli cells
- Androgen binding protein
- Transferrin
- Apolipoprotein J
2 hormones and factors secreted by sertoli cells
- Inhibin
- Anti-Muellerian Hormone
Function of inhibin
Suppression of FSH
Function of Anti-Muellerian Hormone
Promote regression of the Muellerian ducts
Define rete testis
Anastomosed channels lined with a simple epithelium of low cuboidal cells. The epithelium of the rete testis is not surrounded by myoid cells
Two types of cells in the epithelium of the efferent ducts (ductuli efferentes) and their respective functions
Non-ciliated = absorption (endocytic)
Ciliated = move sperm towards epididymis
Role of estrogen in the ductuli efferentes
Stimulate non-ciliated cells of the epithelium to absorb (if receptor gene is knocked out, testis becomes full of fluid)
3 regions of the epididymis
- Head (caput)
- Body
- Tail (cauda)
Type of epithelium in the epididymis
Pseudostratified
Describe the function of the epididymis epithelial cells
Taller columnar cells contain stereocilia that are actually microvilli engaged in absorption
Site of maturation of spermatozoa
Epididymis
Describe the histology of the vas deferens
- Surrounded by lamina propria (several layers of myoid cells)
- Outer smooth muscle cells (non-specifically oriented)
- Taller epithelial cells have stereocilia (pseudostratified)
Type of tissue surrounding the urethra in the penis and what it becomes towards the tip
Corpus spongiosum, which enlarges to form the glans
Erectile tissue of the penis
Corpus cavernosum and corpus spongiosum (contains smooth muscle and endothelium as well as deep arteries)
Tissue surrounding the corpus cavernosum of the penis
Tunica albuginea (NOTE: Different from that of the testis)
Describe the non-erect state of the penis in terms of blood flow
Minimal
Describe how erection physiologically occurs in the penis
- Vasodilator impulses of parasympathetic origin causes relaxation of penile vessels and cavernous smooth muscle
- Amount of blood increases in the vascular spaces of the corpus cavernosa and corpus spongiosum –> rigidity of the penis as it enlarges within the confines of the tough connective tissue of the tunica albuginea.
Define erectile dysfunction
Inability to develop or mantain an erection of the penis for a satisfactory sexual performance
Define Peyronie’s disease
Most consistent abnormality occurs in the orientation and character of the collagen that comprises the tunica albuginea. Plaque is formed and causes erect penis to curve to one side (may be painful and require corrective surgery)
3 types of spermatogenic cells
- Spermatogonia
- Spermatocyte
- Spermatid
Location within the epithelium of seminiferous tubules of spermatogonia
Resting on the basement membrane
Location within the epithelium of seminiferous tubules of spermatocytes
Generally located in the middle of the seminiferous epithelium
Location within the epithelium of seminiferous tubules of spermatids (round and elongated)
Adluminal region
5 histologic characteristics of Sertoli cells
- Elaborate endoplasmic reticulum
- Well-developed Golgi apparatus
- Generally ovoid or triangular nuclei
- Euchromatin and distinct nucleolus in nuclei
- Large number of lysosomes
