Male Reproductive System Flashcards
what acts as the endocrine gland in the Testes?
leydig cells producing and secreting testosterone
what acts as the exocrine organ in the testes?
spematozoa secretion via holocrine secretion (from the seminal tubules)
what type of gland is the testes?
a compound tubular gland
What is the tunica albuginea?
dense irregular CT hat surrounds each testis in a capsule
what is the innermost layer of the tunica albuginea called? what does it contain?
tunica vasculosa = loose CT with blood vessels
what is the mediastinum testis?
a posterior thickening of the tunica albuginea
what divides each testis into lobules? what does each lobule contain?
the septae of CT divides each testis into lobules; each lobule contains 1-3 seminiferous tubules
Where do the seminiferous tubules start? end?
near the mediastinum testes
what does the intersitial CT (aka intersitium aka stroma) of the testes lobules contain?
lympathic vessels, blood vessels, nerves, leydig tells (interstitial cells)
Describe the morphology of leydig cells and staining
larger than other cells of the interstitium, have an eosinophilic cytoplasm and a VESICULATED nucleus with a prominent nucleolus; cytoplasm has lipid droplets ; contains lots of sER and mitochondria (TUBULOVESICUALR CRISTAE)
where are leydig cells found?
in the testicular lobules, BETWEEN SEMINIFEROUS TUBULES
What is the function of Leydig cells
secretion of testosterone (STEROID HORMONE)
Why is testosterone important in males?
it is necessary for development, maturation, and maintenance of male gamete production, reproductive tract function and male secondary sex characteristics
what is the tunica propria?
a layer of dense CT that surrounds each semeniferous tubule; contains MYELOID CELLS
what is the function of myoid cells? where are they found?
function like myofibroblasts, have characteristics of SMC and Fibroblasts;
Function = to contract and help propel secreted spermatozoa along the seminiferous tubule lumen
Found in the tunica propria – surrounding each seminiferous tubule
What separates the tunica propria from the seminiferous epithelium?
basal lamina
Describe the seminiferous epithelium morphology; what cells can be found here?
stratified epithelium containing 1. sertoli cells (epithelial cells) and 2. spermatogenic cells (spermatogonia, spermatocytes, spermatids)
What is the effect of temperature of spermatogenesis?
spermatogenesis occurs at 2-3 degrees LOWER than body temperature; this is maintained by the scrotum (sac) that suspends the testes;
What is the relationship between infertility and body temperature?
Infertility can be caused by elevated temperature because then spermatogenesis ceases even the TESTOSTERONE SECRETION IS UNAFFECTED
What are the most common ways for male infertility?
- Elevated temperature in the testes
- crytoorchidism (undescended testicles)
- Mutagens
- Steroids
- Infections
- Radiation
What are sertoli cells?
seminiferous epithelial cells THAT DO NOT BECOME SPERM; instead they form compartments to organize the spermatogenic cells that are undergoing spermatogenesis
Describe the morphology of sertoli cells?
columnar, stretch from the basal lamina to the lumen of the semeniferous tubule; they have indistinct PM boundaries, an indented vesiculated nuclear and a prominent nucleolus
What is the function of the space between sertoli cells?
it creates a microenvironment needed for the development of the different types of spematogenic cells
what are sertoli-sertoli junctions?
specialized junctions created between 2 neighboring sertoli cells with in a semeniferous tubule
BASIS OF THE BLOOD TESTIS BARRIER
how does the sertoli cell divide the seminiferous epithelium?
into a basal compartment containing spermatogonium and an adluminal compartment containing spermatocytes + spermatids?
what is found in the basal compartment of the seminiferous epithelium? adluminal compartment?
basal = spermatogonia (+spermatocytes very briefly) adluminal = spermatocytes + spermatids
Other than adjacent sertoli cells, what else do sertoli bind to? what does this form?
bind to spermatids within the seminiferous epithelium to form the sertoli-spermatid junction
what is the function of the sertoli-spermatid junction?
anchors spermatid to the sertoli cell during sperm development
How is there a high concentration of testoserone in the seminiferous tubule? why is this important?
sertoli cells produce testosterone binding protein to maintain high [testosterone] in the seminiferous tubules (200 times higher than normal blood vessels); Necessary for spermatogenesis
what do sertoli cells secrete?
fluid to help move the spermatozoa along the lumen of the seminiferous tubule
How does autoimmunity to spermatozoa occur? what happens? What patients usually have this?
if the sertoli-sertoli junctions are compromised, the immune system may detect “foreign” proteins of the spermatozoa which have a different genetic makeup than the host and mount an anti-body response to them ;
Patients who have a vasectomy usually have autoimmunity to their sperm because the vasectomy allows spermatozoa to leak out of the reproductive tract and be exposed to the immune system
What are the 3 stages of spermatogeneis? what their general goal?
- spermatogonial phase: production of spermatocytes by spermatogonial cells
- spermatocyte phase: meiotic divisions of spermatocytes to reduce the DNA content to 1 per cell (haploid)
- Spermatid phase: differentiation of sperm
what is a spermatogonia?
the least developed of the spermatogenic cells that reside within the seminiferous epithelium of the testes
what are the 3 types of spermatogonia? how are they distinguished?
- Ad (dark)
- Ap (pale)
- B
distinguished histologically by their nuclei
How are spematogonia IDed?
any cells resting on the basal lamina and lacking sertoli morphology = spermatogonia
What is true of all spermatogonia?
all are round with a round nucleus and are located next to the basal lamina (basal compartment)
What is the function of Ad type spermatogonia?
divide by mitosis to form another pair of Ad type or a pair of Ap type spermatogonia
what is the function of Ap type spermatogonia?
commit to differentation process that will produce sperm; they go through several rounds of mitosis but DO NOT COMPLETE CYTOKINESIS, forming a cohort and differentiating into type B spermatogonia
what is a cohort with respect to the male reproductive system?
a group of spermatogonia linked together by cell bridges; formed by type Ap spermatogonia undergoing mitosis without cytokinesis
what gives rise to type B spermatogonia?
type Ap spermatogonia
what marks the end of the spermatogonial phase of spermatogenesis?
type Ap differentiating into type B spermatogonia
type B spermatogonia divide via _______ to produce _______________ located in the _______ but moving to the _________.
divide via MITOSIS to produce PRELEPTOTENE PRIMARY SPERMATOCYTES located in the BASAL COMPARTMENT but moving to the ADLUMINAL COMPARTMENT
how do primary spermatocytes migrate from the basal compartment to the adluminal compartment?
via sertoli cells forming new sertoli-sertoli junctions beneath the primary spermatocytes and breaking down the junctions above them
what is the goal of the spermatocyte phase of spermatogenesis?
primary spermatocytes (2n) undergo meiosis with genetic recombination to reduce the chromosome number and amount of DNA
Describe the morphology of primary spermatocytes
largest nuclei of the cells in the semeniferous epithelium and nth nucleus is filled with very basophilic chromatin
How do primary spermatocytes prepare for meiosis? what is the result of the “prep”
they duplicate DNA such that they have normal number of chromosomes (sister chromatids = 46 chromosomes) but TWICE the total amount of DNA compared to interphase
what is the result of meiosis I in spermatogenesis?
two secondary spermatocytes, each with 23 chromosomes and the normal amount of DNA
what is another name for meiosis I?
reductional division
where are secondary spermatocytes located?
in the adluminal compartment
How do spermatocytes prep for meiosis II?
THEY DONT. DO NOT UNDERGO DNA REPLICATION, increase they just go straight into meiosis II
what is another name for meiosis II?
equatorial division
How does the time frame of meiosis I compare to that of meiosis II?
meiosis I = weeks
meiosis II = hours
what is the result of meiosis II?
two spermatids (4 total, 2 spermatids per secondary spermatocyte) , each with 23 chromosomes and 1/2 the normal amount off DNA