histo male repro I

Question 1

What does the male reproductive system consists of?

Answer 1

1. testis
2. genital excurrent ducts
3. accessory sex glands
4. penis

Question 2

what does the male reproductive system produce?

Answer 2

*Produce haploid germ cells spermatozoa

*Hormones
Testosterone and its metabolite dihydrotestosterone, which in the fetus stimulates the development of the external genitalia

*Secretions (semen)
To nourish and propel sperm lubrication for pathway during ejaculation

Question 3

what si the function of the copulatory organ?

Answer 3

to place sperm in female reproductive tract (internal fertilization)

Question 4

what does tunica albuginea cover?

Answer 4

seminiferous tubules and the tunica vaginalis is the most external layer

Question 5

memorize

Question 6

memorize

Question 7

describe the tunica albuginea

Answer 7

unusually thick connective tissue capsule
*Connective tissue from capsule form into lobules, that consist of several convoluted seminiferous tubules, one to four in which sperm is produced.
*Leydig cells are found in the connective tissue stroma

Question 8

idenitfy

Answer 8

testis, seminiferous tubules

Question 9

identify

Answer 9

in connective tissue blue found are leydig cells

Question 10

identify

Answer 10

Pre-pubescent seminiferous tubules. Note absence of both lumen and maturing germ cells. Leydig cells in the interstitium are inactive. sertoli cells prominent

Question 11

identify

Answer 11

Post-puberty seminiferous tubules. Note lumen, developing germ cells at various stages within a single tubule, and active Leydig cells in the interstitium. myodal cells permit contraction for ejaculation in periphery of seminiferous tubules

Question 12

which cells are present in the seminiferous tubules?

Answer 12

1. Sertoli cells are supporting or sustentacular cells for developing germ cells. These cells do not replicate after puberty. Sertoli cells have extensive apical and lateral processes and extend trough the full thickness of the seminiferous tubes. Provide structural organization to the tubules
2. Spermatogenic cells
   Derived from primordial germ cells originating in the yolk sac. The most immature spermatogenic cells called spermatogonia, rest on the basal lamina

Question 13

describe the seminiferous tubules

Answer 13

Each seminiferous tubule is approximately 50 cm long (range, 30 to 80 cm) and 150 to 250 μm in diameter

Question 14

identify

Answer 14

The connective tissue around seminiferous tubules is the Interstitium: Contains myoid cells contain abundant actin filaments.
Leydig cells (Interstitial cells)

Question 15

identify

Answer 15

The connective tissue around seminiferous tubules is the Interstitium: Contains myoid cells contain abundant actin filaments.
Leydig cells (Interstitial cells)

Question 16

describe leydig cells

Answer 16

Leydig cells (interstitial cells) are large, polygonal, eosinophilic cells that typically contain lipid droplets.

found in leydig cells: Rod-shaped cytoplasmic crystals, the crystals of Reinke. Although their exact nature and function remain unknown, they probably represent a protein product of the cell.

Question 17

identofy

Answer 17

Crystal
of Reinke

Question 18

identify

Answer 18

leydig cells

Question 19

when do leydig cells secrete testosterone?

Answer 19

Leydig cells differentiate and secrete testosterone during embryonic development, sexual maturation, and reproductive function

Question 20

what are the functions of the testosterone secreted?

Answer 20

endocrine and paracrine (seminiferous tubules) activities

Question 21

explain the importance of testosterone secretion in the embryo, during puberty and in the adult?

Answer 21

*In the embryo, secretion of testosterone is essential for the normal development of the gonads in the male fetus. Leydig cells also secrete insulin-like protein 3 (INSL3) that stimulates descent of the testis during development.

*At puberty, secretion of testosterone is responsible for the initiation of sperm production and development of secondary sex characteristics. Secretion of INSL3 also promotes meiotic divisions in the seminiferous tubules.

*In the adult, secretion of testosterone is essential for the maintenance of spermatogenesis and of secondary sex characteristics. Leydig cells in the adult testes are the chief source of circulating insulin-like factor 3 (INSL3) protein.

Question 22

what other hormone does leydig cells secret?

Answer 22

Leydig cells produce and secrete oxytocin. Testicular oxytocin stimulates contraction of myoid cells that surround the seminiferous tubules, moving the spermatozoa toward the efferent ductules.

Question 23

what is spermatogenesis and when doe sit happen?

Answer 23

Spermatogenesis is the process by which spermatogonia develop into sperm

It begins shortly before puberty, under the influence of rising levels of pituitary gonadotropins

Question 24

what are the spermatogensis distinct phases?

Answer 24

1. Spermatogonial phase, in which spermatogonia divide by mitosis to replace themselves as well as provide a population of committed spermatogonia that will eventually give rise to primary spermatocytes (MITOSIS)
2. Spermatocyte phase (meiosis), in which primary spermatocytes undergo two meiotic divisions to reduce both the chromosome number and amount of DNA to produce haploid cells called spermatids
3. Spermatid phase (spermiogenesis), in which spermatids differentiate into mature sperm cells

At the end of spermatogenesis, spermatids undergo their final maturation and are released from the supporting Sertoli cells during a process called spermiation.

Question 25

xplain the spermatogonial phase completely

Answer 25

stem cells divide to replace themselves and provide a population of committed spermatogonia. Three types:

1. Type A dark (Ad) spermatogonia have ovoid nuclei with intensely basophilic, finely granular chromatin. These spermatogonia are thought to be the stem cells.
2. Type A pale (Ap) spermatogonia have ovoid nuclei with lightly staining chromatin. Ap spermatogonia are committed to the differentiation process that produces the sperm.
3. Type B spermatogonia have generally spherical nuclei with chromatin that is condensed into large clumps in the nucleus.

An unusual feature of the division of spermatogonium into two type Ap spermatogonia is that the daughter cells remain connected by a thin cytoplasmic bridge.

These cytoplasmic connections are essential for the synchronous development

Question 26

Explain the spermatocyte phase (meiosis) completely

Answer 26

primary spermatocytes undergo meiosis to reduce both the chromosome number and the amount of DNA.

The mitotic division of type B spermatogonia produces primary spermatocytes. They replicate their DNA shortly after they form and before meiosis.

*Primary spermatocyte contains the normal chromosomal number (2n). meiosis I results in reduction of both the number of chromosomes (from 2n to 1n) and the amount of DNA to the haploid number (from 4d to 2d) lasts up to 22 days in humas.

*Secondary spermatocytes have a haploid number of chromosomes (1n) and 2d amount of DNA. Because NO DNA replication precedes meiosis II, after this division spermatids are formed. (1n) and (1d). The second meiotic division is short and lasts only several hours

*Each spermatocyte undergoes meiosis to form four haploid spermatids.

Question 27

explain the spermatid phase completely (spermiogenesis)

Answer 27

In the spermatid phase, spermatids undergo extensive cell remodeling as they differentiate into mature sperm.

Each spermatid that results from the second meiotic division is haploid in DNA content (1d) and chromosome number (1n) represented by 22 autosomes and an X or Y chromosome. No further division occurs..

The extensive cell remodeling that occurs during differentiation of the spermatid population into mature sperm (spermiogenesis) consists of four phases:
*The Golgi phase
*The cap phase
*The acrosome phase
*The maturation phase.

These phases occur while the spermatids are physically attached to the Sertoli cell plasma membrane by specialized junctions.

Question 28

explain the 4 phases of the spermiogensis spermatid phase

Answer 28

Remodeling of spermatids

*Golgi phase (Early Spermatids)
Establish polarity and develop axoneme and acrosomal vesicle. That determines the anterior pole.

*Cap phase The acrosomal vesicle spreads and develop acrosomal cap.
The nuclear contents condense. Protamines replace the histones.

*Acrosome phase (Late spermatids): Reorient and reorganize itself. The head becomes deeply embedded in the Sertoli cell. The cytoplasmic microtubules become organized into a cylindrical sheath the manchette and the flagellum extends into the lumen.

*Maturation phase
Excess cytoplasm from around flagella is reduced, to form mature spermatozoon. Sertoli cells phagocytose this residual cytoplasm.

Question 29

explain the parts of the spermatocyte

Answer 29

*Head (nucleus and acrosome)

*Neck
(centrioles, origin course fibers)

*Tail
Middle piece (mitochondria)

Principal piece (fibers and axoneme of flagellum)

End piece (only axoneme)

primary ciliary dyskinesia; mutacion en patitas de dyenin; no mobilidad de sperm so probelmas de infertilidad)

Question 30

explain the sertoli to spermatid junctional complex

Answer 30

Spermiation involves progressive removal of specialized Sertoli-to-spermatid junctional complexes and disengagement of spermatids from the Sertoli cell.

The presence of β1-integrins in the Sertoli-to-spermatid junctions, as well as increased activity of integrin-linked kinase at the time of spermiation, suggests enzymatic control of spermatid release.

The rate of spermiation in the testis determines the number of sperm cells in the ejaculate of semen.

Question 31

identify

Answer 31

late rspermatid and the junctional complex qwith sertoli cell

Question 32

explain spermiation and what can affect this process?

Answer 32

Immotile sperm are released from the Sertoli cells by the process called spermiation. Sertoli cells phagocytose the remaining cytoplasm (residual bodies).

Various pharmacologic treatments, toxic agents, and gonadotropin suppression result in spermiation failure, in which spermatids are not released but instead are retained and phagocytosed by the Sertoli cell.

Question 33

identify

Answer 33

1. spermatogonia
2. primary spermatoides
3. early spermatid
4. late spermatids
5. sertoli cells

Question 34

how does spermiation occur?

Answer 34

At the time of spermiation, sperm are both nonmotile and incapable of fertilizing an oocyte.
Sperm gain motility as they pass through the epididymis.
Sperm can live several weeks in the male duct system but only 2-3 days in the female duct system.

Question 35

WHAT is capacitation?

Answer 35

Final maturation occurs within the female reproductive tract (vagina and oviduct) Gives the sperm the ability to fertilize an oocyte. Biochemical changes consists of removal and replacement of glycocalyx components on the sperm plasma membrane.

Question 36

mention the developing germ cells in seminiferous tubules

Answer 36

1.spermatogonia (types A and B)
2.primary spermatocytes (prophase)
3.secondary spermatocytes
4.spermatids (* early and * late)
5. spermatozoa (released in lumen)

Question 37

identify

Answer 37

1.spermatogonia (types A and B)
2.primary spermatocytes (prophase)
4.spermatids (* early and * late)
sertoli cells

Question 38

what are the stages of the seminiferous epithelium

Answer 38

Differentiating spermatogenic in the seminiferous epithelium is not random.

Specific cell types are grouped together and they have intercellular bridges, present between the progeny, that undergo synchronous mitotic and meiotic divisions and maturation.

Each is considered a stage (6 stages) in a cyclic process. The series of stages constitutes a cycle of the seminiferous epithelium.

In humans, for a spermatogonium to complete the process of spermatogenesis, takes approximately 74 days.

It would then require approximately12 daysfor the spermatozoon topass through the epididymis.

In any pharmacologic intervention, approx. 3 months are required to see the effect

300,000,000 of sperm a day

Question 39

which are the true epithelium of the seminiferous tubules

Answer 39

sertoli cells

Question 40

describe histologicallt sertoli cells

Answer 40

*Sertoli cells (sustentacular cells) are tall, columnar, nonreplicating epithelial cells that rest on the thick, basal lamina of the seminiferous epithelium.

*They are the supporting cells for the developing spermatozoa that attach to their surface after meiosis. Sertoli cells contain an extensive sER, rER, numerous mitochondria, amd well-developed Golgi apparatus.

*The cytoskeleton of the Sertoli cell is one of the most elaborate in the human body.

*Inclusion bodies (of Charcot-Böttcher) are found in the cytoplasm. These crystalloids are unknown function, possible involved in lipid transport and utilization in the Sertoli Cell.

Question 41

identify

Answer 41

Electron micrograph of a human Sertoli cell. This electron micrograph shows characteristic crystalloid inclusion bodies of Charcot-Böttcher in the basal cytoplasm of the Sertoli cell

Question 42

what dos the sertoli cell-to-sertoli cell junctional complex do?

Answer 42

is the site of the blood–testis barrier. This barrier is essential in creating a physiologic compartmentalization within the seminiferous. The blood–testis barrier isolates the genetically different and therefore antigenic haploid germ cells from the immune system of the adult male.

separates a absal compartment and a luminal compartment

Question 43

what are the exocrine secretory prodcuts of sertoli cells and function?

Answer 43

particularlyandrogen-binding protein [ABP], which has a highbinding affinity for testosterone and DHT) are highly concentrated in the lumen of the seminiferous tubules and maintain a high concentration of testosterone

Question 44

how are sertoli cells bounded to each other?

Answer 44

Sertoli cells are bound to one another by an unusual Sertoli cell–to–Sertoli cell junctional complex. This complex is characterized, in part, by tight junction (zonula occludens) that includes more than 50 parallel fusion lines in the adjacent membranes.

Question 45

hat characterizes the junctional complex of sertoli cell to sertoli cell?

Answer 45

1) A flattened cisterna of sER lies parallel to the plasma membrane in the region of the junction in each cell.

2) Actin filament bundles, hexagonally packed, are interposed between the sER cisternae and the plasma membranes.

Question 46

identify

Answer 46

Electron micrograph of Sertoli cell junctions.
Sertoli-to-Sertoli junctional complex and a Sertoli-to-spermatid junctional specialization. Condensation and shaping of the spermatid nucleus (N) are well advanced. The associated SER resides immediately adjacent to the microfilament bundles. The Sertoli-to-Sertoli junction lies below, joining one Sertoli cell (S1) to the adjacent Sertoli cell (S2). The arrowheads indicate the limits of the junction

Question 47

what are the exocrine and endocrine secretory functions of sertoli cells:

Answer 47

1)They secrete androgen-binding protein (ABP). [aumenta testosterona en lunen]

2) FSH and testosterone receptors are present on Sertoli cells; therefore, their secretory function is regulated by both FSH and testosterone. [FSH produced by gonadotropins basophils of adenohypophysis]

3) Sertoli cells secrete several endocrine substances, such as inhibin, a hormone involved in the feedback loop that inhibits FSH release from the anterior pituitary gland.

4) Sertoli cells synthesize plasminogen activator, which converts plasminogen to the active proteolytic hormone plasmin.

5) Sertoli cells secrete other glycoproteins that function as growth factors or paracrine factors, such as Müllerian-inhibiting factor (MIF), stem cell factor (SCF), and glial cell line–derived neurotrophic factor (GDNF).

Question 48

how temperature influences on spermatogensis?

Answer 48

Temperature – normally blood to testes is cooler than the temperature in he body core.

In undescended testes (Cryptorchid) the seminiferous tubules are made of primarily Sertoli Cells. If testes are moved to scrotum before the boy is two years old, spermatogonia are not damaged. Testosterone (Leydig cells) normal even if undescended.

Question 49

identify

Answer 49

cryptorchid (sertoli cells oinly

Question 50

how does FSH impact sertoli cells?

Answer 50

Low levels of testosterone stimulate FSH released →induces Sertoli cells to secrete Androgen Binding Protein (ABP) → binds testosterone within tubule and raises testosterone levels in local environment.

Testosterone also targets Sertoli
cells and stimulates sperm production

Negative feedback mechanism
inhibin from Sertoli cells inhibits
FSH and converts testosterone to estradiol →inhibits Leydig cells

Question 51

hwo does hormones impact spermatogensis on leydig cells?

Answer 51

▪Luteinizing Hormone (LH)
is also called Interstitial cell-stimulating hormone (ICSH), bind receptors on Leydig cells → secrete testosterone

*Estrogens and progestogens inhibit spermatogenesis since they bind to androgen binding protein (ABP) thus preventing the binding of testosterone.

*High local levels testosterone
needed to maintain other genital
organs

*Nutrition, alcohol, some drugs,
temperature, radiation, etc. also
can cause sterility.