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Histology and Physiology Reproduction System > Testes and Spermatogenesis > Flashcards

Testes and Spermatogenesis Flashcards

1
Q

main testis function (general)

A

sperm and androgen production

- nearly all testosterone is made by them (Leydig cells
5% is made in zona reticularis of adrenal gland)

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2
Q

dense irregular CT surrounding the testes

A

tunica albuginea

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3
Q

mediastinum testis

A

inward projection of the tunica albuginea on the posterior surface of the testis

holds the rete testis

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4
Q

septa in testis

A

CT going from the capsule inward

splits the testis into 250 lobules

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5
Q

Cells that are not inside the convulted tubule in testis

A

fibroblasts = cells with a thin nucleus outside of the tubule

Leydig cells = bigger cells with bigger nucleus outside of the tubule

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6
Q

Leydig cells

A

make and secrete testosterone

variable in size but round usually

cytoplasm = acidophilic

a lot of large smooth ER and filled with lipid droplets to create steroids

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7
Q

inside the convoluted seminiferous tubule

A

consists of lamina propria with myoid cells and collagen fibrils

basement membrane

seminiferous epithelium = complex stratified
- has sertoli cells and spermatogenic cells on top of one another

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8
Q

myoid cells in convoluted seminiferous tubule

A

flat elongated SmM like cells that contract to move sperm and fluid in the duct system

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9
Q

where a more immature spermatogenic cells located?

A

rest on basal lamina = ‘spermatogonia’

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10
Q

spermatids

A

most mature spermatogenic cells

located at the apical portion of sertoli cells (bordering the lumen)

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11
Q

progression of spermatogenesis (general)

A

1 spermatogonum –>

1 primary spermatocyte –> 1st round of meiosis

2 secondary spermatocyte –> 2nd round of meiosis

4 total spermatids –> maturation (spermiogenesis)

4 spermatozoa (mature sperm cells)

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12
Q

the secondary spermatocyte cells to the late spermatids are connected via….

A

cytoplasmic bridge

essential for synchrous development

allow free communication between cells

***allow haploid cells to be supplied with proteins and RNAs encoded by complete diploid genome

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13
Q

how does the cytoplasmic bridge go away

A

sertoli cells phagocytose the unneeded cytoplasm while making mature…

spermatozoa

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14
Q

what spermatocyte are really hard to find histologically

A

secondary

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15
Q

spermatogonia

A

most immature and relatively large

rounded nucleus with chromatin

always in contact with basal lamina, so very easy to spot

divide and differentiate into primary spermatocytes

3 types:

  1. type A dark
  2. type A pale
  3. type B

do not need to be able to tell the difference

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16
Q

primary spermatocyte

A

largest germ cell present and cells that are spherical or ovoid

large round nucleus with heterochromatin***

undergo first meiosis to produce 2 secondaries

17
Q

when does genetic variation via crossover and random inclusion of either paternal chromosome occur?

A

1st meiosis

primary –> secondary spermatocyte

18
Q

secondary spermatocyte

A

half the size as primary

differentiates into 2 spermatids

19
Q

spermatids

A

will undergo no further division…instead undergo spermiogenesis and differentiate into spermatozoa

early spermatids =
- small size, with round nuclei and condensed chromatin

late

  • elongated, condensed nucleus
  • has a tail and is attached to apical portion of sertoli bordering the lumen
  • looks like sperm but the cytoplasmic cross bridge still present
20
Q

4 processes of spermiogenesis

A
  1. nuclear condensation and elongation
  2. acrosome formation to break down zona pellucida of ovum and allow for fertilzation to occur
  3. flagellum formation
  4. cytoplasm reduction
21
Q

rate of spermiation determines what

A

of sperm in semen

22
Q

spermatozoon

A

free in lumen

much of cytoplasm has been phagocytosed by sertoli cells

released as non-motile, gain motility in epididymis, wehre they are stored before ejaculation

23
Q

sertoli cells GENERAL function

A
  • structural organization to the tubules
  • support and nurse maturing sperm cell by exchanging substrates and wastes…also phagocytosed unneeded cytoplasm
  • unable to differentiate
  • extend from basement membrane to lumen surface of epithelium
24
Q

structure of sertoli cells

A

tall and columnar

nucleus is ovoid, triangular, and large and lightly staining

nucleolus is large and prominent (like eye of owl)

cell borders are not visible

well developed RER, SER, lipid droplets, and lots of mitochondria

25
Q

endocrine functions of sertoli cells

A

estradiol = aromatase converts testosterone –> estradiol in neonatal and prepubertal mammals to inhibit testosterone production by leydig cells and regulate spermatogenesis

inhibin B = (-) feedback on FSH

mullerian-inhibiting factor (MIH) = cause regression of mullerian ducts

growth factors (GDNF and stem cell factor) = maintain the number of spermatogonia

26
Q

exocrine sertoli cell

A

fluid = helps move sperm along seminiferous tubules to intra-testicular ducts

androgen binding protein (ABF) - promoted by FSH

  • binds testosterone to make it lipophilic and keep it in the lumen of the tubules
  • more testosterone in lumen is best for sperm production
27
Q

tight junction between sertoli cells

A

divide epithelium into basal and adluminal compartments

basal = spermatogonia and early spermatocytes

adluminal = rest of the cells

early spermatocytes move to adluminal compartment by sertoli cells making a new tight junction under the cell that is moving compartments…the tight junction above the cell degrades

forms the basis for blood-testis barrier
- allow ionic, amino acid, carb, and protein composition to be different from that of blood plasma

28
Q

where does meiosis and spermiogenesis occur

A

adluminal compartment

29
Q

what is very sensitive to elevated temperature

A

seminiferous epithelium (not spermatogonia)

why testis dangle outside body

30
Q

Cryptorchidism

A

undescended testis - causes degeneration of spermatogenic cells, besides spermatogonia, leaving only intersitial structures like fibroblasts and leydig cells

31
Q

how is temperature in testis regulated

A

through the pampiniform plexus

has a countercurrent heat exchange between the plexus and the testicular artery to cool off the arterial blood

also uses cremaster muscle and dartos muscle

32
Q

pampiniform veins

A

have uncharacteristically thick SmM, which allows for propulsion of blood against gravity into abdominal veins

33
Q

Cremaster reflex

A

works by contraction and relaxation of the cremaster (skeletal) allowing scrotum to move toward or away from the body to regulate temperature

cold temperature also causes dartos (SmM) muscle of the scrotum to contract
–> scrotum wrinkles which helps regulate heat loss

Histology and Physiology Reproduction System (12 decks)

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