Flashcards in Male Reproductive System Deck (134):
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?
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?
1. Elevated temperature in the testes
2. crytoorchidism (undescended testicles)
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?
1. spermatogonial phase: production of spermatocytes by spermatogonial cells
2. spermatocyte phase: meiotic divisions of spermatocytes to reduce the DNA content to 1 per cell (haploid)
3. 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?
1. Ad (dark)
2. Ap (pale)
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?
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?
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
In general what is spermatogensis?
1 diploid spermatogonia in the basal compartment to 4 haploid spermatids in the adluminal compartment
describe the morphology of the early (round) spermatid
small, round, dark basophilic nucleus, NO STRANDS OF CONDENSED CHROMATIN NUCLEUS
Do spermatids undergo meiosis? mitosis?
NO TO BOTH, they only undergo a series of biochemical + morphological changes (spermatogenesis phase)
What are the 4 phases of the spermatid phase of spermatogenesis?
1. Golgi phase
2. Cap phase
3. Acrosome Phase
4. Maturation Phase
Describe the golgi phase of spermatogensis
1. spermatids produce acrosomal vesicles from the golgi apparatus
2. Tail microtubules (Axoneme) begin to form
what is the acrosomal vesicle? where is it located?
membrane bound vesicle next to the nuclear envelope (formed during the golgi phase of spermatogenesis)
What does the acrosomal vesicle contain?
hydolytic enzymes = hyalurinidase, acrosin, neuraminidase
what is the function of the acrosomal vesicle's contents?
hydolytic enzymes to help penetrate the coverings of the ovum and receptors for the zona pellucida surrounding the ovum
What happens during the cap phase of spermatogensis?
1. acrosomal vesicle flattens against round (early) spermatid nucleus to form a "cap"
2. Tail also elongates
What happens during the acrosomal phase of spermatogensis?
1. Nucleus condenses and elongates, giving the sperm head a pointed appearance
2. Mitochondria migrate to the initial portion of the axoneme, adjacent to the neck, forming a spiral wrapping to constitute the "middle piece" of the spermatozoan
what happens in the maturation phase of spermatogenesis?
excess cytoplasm extruded into a residual body, which is usually phagocytoized by nearby sertoli cells
What are the major morphological changes that occur during the spermatid phase of spermatogensis?
1. During acrosome phase, the late (elongated) spermatids with small dense triangular heads form
where are late (elongated) spermatids located?
very close to the lumens of seminiferous tubules
What happens to the late (elongarted) spermatids?
they are shed from the seminiferous tubules to become spermatozoa
what are spermatozoa?
nonmobile sperm incapable of fertilization
how do spermatozoa move?
they are immobile therefore they move passively along the seminiferous tubule lumen by flow of the fluid secreted by the sertoli cells and by contractions of the myoid cells (of tunica propria)
What are the stratight tubules (tubuli recti) in the testes?
intratesticular ducts located at the ends of seminiferous tubules where they meet the mesiastium testis
what type of epithelium line the straight tubules (tubuli recti) of the testes?
simple cuboidal epithelium
What are the rete testis?
intratesticular duct system of interconnecting epithelial-lined channels within the CT mediastinum testis
what type of epithelium lines the rete testis?
what is the function of the straight tubules and the retes testis?
to transport spermatozoa from the seminferous tubules to the epididymal duct via movements of the testicular fluid (with sperm) through the duct
What forms the efferent ductules of the testes?
fusion of the retes testes
are efferent ductules intratesticular or extratesticular ducts?
what acts as the bridge between the testes and the epididymis?
what is formed by the efferent ductules merging?
the head of the epididymis
what type of epithelium is found in the efferent ductule?
pseudostratified columnar made of alternating tall ciliated columnar and non-ciliated cuboidal ;
incomplete layer of basal cells
where is most of the testicular fluid secreted by the sertoli cells reabsorbed?
in the efferent ductules by the non-ciliated cuboidal cells
how does sperm move through the efferent ductule?
facilitated by the action of the ciliated epithelial cells and the contraction of SMC layer that surrounds the ductule
What is the epididymal duct?
a single high coiled tube that extends 5-6 m long!
Describe the epithelium found in the epididymal duct
Pseudostratified columnar with principal cells and basal cells (+some narrow cells, clear cells, and halo cells)
Describe the morphology of the principal cells of the epididymal duct
apical surface has non-motile branched stereocilia (elongated microvilli)
what are the functions of the principal cells of the epididymal duct?
1. absorption of testicular fluid that wasnt absorbed by efferent ductules (mainly at epididimis head)
2. phagocytosis of abnormal spermatozoa and residual body
3. Secretion of glycerylphosphorylcholine (GPC), glycoproteins and other molecules for maturation of spermatozoa (for motility and fertility)
what allows for sperm to be motile and fertile?
Secretion of glycerylphosphorylcholine (GPC), glycoproteins and other molecules from the prinicpal cells of the epididimis
what cells secrete glycerylphosphorylcholine (GPC)
principal cells of the epididymal duct
where are mature sperm stored?
in the epididymal tail
What is the function of basal cells of the epididymal duct?
1. precursors for principal cells
2.regulat electolyte and water transport by the principal cells
What surrounds the epididymal duct? Does it's morphology change?
surrounded by SMC that gets progressively thicker, such that the tail has 3 layers of SMC
What is the ductus dereferns a continuation of? what does it expend to?
continues directly from the tail of the epidimis and is a component of the spermatic cord
Describe the mucosa layer of the ductus deferens
epithelium = PSC similar to epididymal duct + STEREOCILIA until the ampula
LP = contains elastic fibers
Describe the muscularis layer of ductus deferens
inner longitudinal, middle circular, and outer longitudinal layers;
How is sperm propelled during ejaculation?
due to the peristaltic activity of the muscular wall of the ductus deferens
Describe the adventitia layer of the ductus deferens
loose elastic CT that blends with the CT of structures in spermatic cord
what is the ampulla of the ductus deferens?
dilated region of the ductus deferens adjacent to the prostate and the seminal vesicle
describe the epithelium of the ampulla of the ductus deferens
becomes folded and resembles that of a seminal vesicle; epithelium may have secretory function
What is the function of the accessory glands of the male reproductive system?
they are secretory glands that provide fluid and nutrients to support and nourish the spermatozoa (fluids form the bulk of semen)
what do all accessory glands depend on? for what?
testosterone for mophological development and physiological activity
what are the seminal vesicles?
paired, elongate, and highly folded tubular glands that secrete tons of fluid for semen (largest contributor to semen volume)
Describe the epithelium of the seminal vesicles (morphology)
PSC but can vary with aging or with amount of testosterone present
Describe the morphology of the mucosa of the seminal vesicles and how it contributes to its function
extensively branched and folded, creating a large surface area for secretion
What does the epithelium of the seminal vesicles secrete?
FRUCTOSE (+ other sugars), bicarbonate, prostaglandins, proteins, amino acids
describe the lamina propria of the epithelial cells of the seminal vesicles
loose CT, vasculatized, elastic fibers
Describe the muscularis layer of the seminal vesicles
inner circular + outer longitudinal SMC
Describe the adventitia of the seminal vesicles
collagenous CT with many elastic fibers
What does the seminal vesicle connect to? how? what does this form?
combines with the ampulla of the ductus deferns as they enter the prostate gland via a short excretory duct; forms the ejaculatory duct
Where is the prostate gland located?
surrounds the prostatic segment of the urethra
How is the prostate gland organized? Describe the organizations
into zones of tubulo-alveolar glands around the urethra:
1. Main prostatic gland = peripheral zone
2. Submucosal gland = central zone
3. mucosal glands = transitional zone
what do the ducts of each zone of the prostate converge to form?
an excretory duct that opens into the prostatic urethra
Describe the epithelium of the prostate
varies between simple columnar and PSC, depending on adequate levels of testosterone
what is the effect of inadequate testosterone on the epithelium of the prostate?
results in a change in the epithelial shape and loss or reduction in secretory activity
what do the epithelial cells of the prostate secrete?
prostate specific acid phosphatase, citric acid, fibrinolysin (liquifies semen), prostatic specific antigen (protease), and amylase
What is found in the lumen of the prostatic glands?how does it stain?
calcified bodies called prostatic concretions; stains eosinophilically
what is found in the stroma of the prostate gland?
fibromuscular stroma = SMC + Fibroblasts + elastic + collagen fibers
What causes benign prostatic hyperplasia?
As men age, mucosal and submucosal glands and the prostatic stroma begin to hypertrophy which occurs by the conversion of testosterone to DHT via 5-reductase (which causes a growth factor production leading to hyperplasia)
What is the effect of DHT on the prostate?
acts as an autocrine factor of the stromal cells and a paracrine factor on the epithelium to produce growth factors
What does benign prostatic hyperplasia cause?
since it is causing hyperplasia of both stroma and epithelium, and the prostate is located adjacent to the prostatic urethra, the enlarged tissue gradually decreases the lumen of the urethra resulting in difficulties urinating
Where do most tumors develop in in prostatic cancer?
in the main (outer) glands)
How is prostatic cancer usually detected?
by the prostate impinging on the urethra;
also blood levels of PSA and prostatic specific acid phostatas
what does a prostatic carcinoma cause?
an increase in blood levels of PSA and prostatic specific acid phostatase --- both used to detect and monitor progress of disease.
Where are the ducts of the bulbourethral glands located? where do they open into?
located in the UG diaphragm; open into the penile urethra
what type of glands are all of the bulbourethral glands? what are they all lined by?
ALL MUCUS GLANDS; all lined by tall epithelium
what surrounds the corpus cavernosum and corpus spongiosum?
tunica albuginea (dense collagenous sheath)
what does the skin covering the penis contain?
a thin subcutaneous layer of SMC
How is the male urethra organized?
into 1. prostatic 2. membranous 3. penile segments
where is the penile portion of the male urethra located?
in the copus spongiosum
what type of epithelium is found in the male urethra?
stratified or pseudo strat. columnar
what are the glands of Litre?
MUCUS glands common as outpouching of the urethra
What is the morphology of erectile tissue of the penis?
interconnecting vascular spaces (lacunae) lined with endothelium and composed of trabeculae (dense CT + SMC)
What molecules effect an erection?
Nitrous oxide (NO) and a specific phosphodiesterase
How is an erection produced?
ACh (released by the PS nerves in the penis/clitoris) act on the endothelium of erectile tissue to produce NO; NO spreads into the SMC of trabeculae and helicine arteries causing and enzyme, gunylate cyclase, to produce cGMP, which relaxes SMC; this causes an increase in blood flow, filling the lacunae with blood and producing an erection
What is the effect of phosphodiesterase on an erection?
it breaks down cGMP to constrict SMC