Flashcards in Lecture 4: Histology of the Male Reproductive System Deck (36)
What are the four parts of the male reproductive system?
1. Testis-production of spermatozoa and secretion of male sex hormones
2. Genital ducts: collect, store and conduct spermatozoa from each testis
3. Accessory glands: secrete a NUTRITIVE and LUBRICATING fluid called seminal fluid
4. Penis: copulating organ
What is spermiogenesis?
The process by which haploid spermatids are transformed into spermatozoa
Where does spermatogenesis take place?
The pyramidal compartments (lobules)
-empties into rete testis
What are myoid cells?
They have components of smooth muscle; helps sperm propel from seminiferous tubule to rete testis
Lie in the BASAL LAMINA of the seminiferous tubule
Help with spermatogenesis
What are characteristics of Leydig cells?
1. Secretes testosterone
2. Has eccentric nuclei
What is the point of cytoplasmic bridges?
To exchange proteins from sperm to sperm (because some sperm only have X while others only have Y)
What is the tunica albuginea?
The dense fibrous capsule the surrounds the testis
Also surrounds the corpus cavernosum/spongiosum
How is testis divided?
By interlobular septa into 250 pyramidal compartment or testicular lobules
Each esticular lobule contiains 1-4 seminiferous tubules
What are seminiferous tubules?
Where spermatozoa are ultimately produced
What lies between seminiferous tubules?
FibroCOLLAGENOUS tissue that contains
1. leydig cells (interstitial cells)
4. blood and lymphatic vessels
What is TEX14? Significance?
A testis-expressed gene for a novel protein that localizes to germ cell intercellular BRIDGES
No TEX14 = no cytoplasmic bridges
Hence TEX14/cytoplasmic bridges = essential for fertility
What happens when you have no intercellular bridges?
You halt the first meiotic division of male spermatogenesis
What is spermatozoa?
The PROPER term for mature sperm
Mature sperm = spermatozoa
Where are spermatogonia located?
CLOSEST to the basal lamina
What are the two types of spermatogonia?
Type A spermatogonia: dark chromatin, dark all over
Type B spermatogonia: condensed chromatin
What are the principal changes that occur to spermatids in spermiogenesis?
1. Development of an acrosome
Acrosome = lysosome
2. Creation of a residual body
3. condensation and elongation of nucleus
4. Development of flagellum
5. loss of much of cytoplasm
What is the most notable difference between gametogenesis of male and female?
Each spermatocyte that undergoes meiosis, you get 4 gametes
Female oogona that undergo meiosis only forms 1 gamete
What is the course of male gaemetogenesis?
3. Primary Spermatocytes
(Reductional division = 2n n)
4. Secondary Spermatocytes
(Equational division n n)
6. Late spermatid
7. Mature spermatoZOA
What are the stages of spermiogenesis?
1. Golgi phase
2. cap phase
3. Acrosome phase
4. Maturation phase
What is Kartagener Syndromer?
Immotile spermatozoa and resulting infertility
Absence of DYNEIN or other proteins required for flagellar motility
Associated with chronic respiratory infections because this means that respiratory epithelial cilia aren’t working either
What does Type B spermatogonia do?
Differentiates into primary spermatocytes, which then enter meiosis
Can you see secondary spermatocytes in cross section?
No because this is such a transient state
What is the role of Sertoli cells?
1. Support, protect and provide nutrition to the developing germ cells
2. Phagocytize residual bodies and abnormal germ cells
3. Secretes the following:
i. androgen-binding protein (concentrated in luminal side of Sertoli Cell)
ii. Inhibin (negative feedback for FSH)
iii. Activin (positive feedback)
4. Produce anti-Mullerian Hormone (fetal stage)
What is preleptotene?
Earliest stage of prophase in meiosis
What are the two compartments of the seminiferous tubule as determined by sertoli cell? Significance?
-contains the spermatogonia
-cells in this compartment have access to material found in blood
-contains spermatocytes and spermatids
-is protected from blood by blood-testis barrier
What is the composition of blood-testis barrier?
Formed by the tight junctions of the Sertoli Cells
What are the functions of the blood-testis barrier?
1. Divides the testis into a basal compartment and an adlumenal compartment
2. Protects more advanced stages of spermatogenesis from blood-borne products
-so won’t get killed by lymphocytes
What is the function of the epididymis?
1. Accumulation, storage and maturation of sperm
2. Epithelium of epididymis
-resorbs testicular fluid
-phagocytizes residual bodies and degenerate spermatozoa
-secretes glycoproteins, sialic acid, glycerylphophorylcholine
What is the process of sperm maturation in the epididymis?
Includes stabilization of condensed chromatin
-changes membrane surface charge and new surface proteins
-acquisition of motility