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Histo > Male Reproductive System > Flashcards

Male Reproductive System Flashcards

1
Q

Function of male reproductive systme

A
  • Reproduction
  • Production of androgens for reproduction & development of secondary male characteristics
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2
Q

Testis function

A

Spermatogenesis

Steroidogenesis: production of androgens (testosterone)

The adrenal glands are responsible for producing only <5% of testosterone, the rest is in the testis

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3
Q

Structure of testis

A
  • Tunica albuginea: thick, dense irregular connective
  • Mediastinum testis: inward projection of thickened tunica albuginea in posterior surface of the testis
    • Excurrent ducts, blood vessels, and lymphatic vessels go through here
  • Septa: connective tissue projected from the capsule separating each testis into lobules
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4
Q

Where do blood vessels and efferent ductules go through?

A

Mediastinum: connective tissue region

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5
Q

Rete testes

A

Maze of interconnecting channels within the mediastinum testis.

Gives rise to straight tubules/tubuli recti, which leads to convoluted seminiferous tubules

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6
Q

A single testicular lobule (L) is composed of

A

1-4 highly convoluted seminiferous tubulesspread throughout interstitialconnective tissue stroma

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7
Q

Interstitial connective tissue between seminiferous tubules

A

Loose connective tissue containing

  • Fibroblasts - flat nuclei (mouse arrow)
  • Leydig/interstitial cells - lots of cytoplasm
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8
Q

Leydig cells - what is their function?

A

Synthesize & secrete testosterone

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9
Q

How do Interstitial/leydig cells appear histologically?

A
  • Forms small clusters
  • Round or polygonal in shape
  • Acidophilic cytoplasm
    • Like all steroid-producign cells, they have a elaborate sER and a lot of lipid droplets
  • Large & round nucleus*
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10
Q

Function of seminiferous tubule

A

Sperm production

super long and convoluted

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11
Q

Wall of the seminiferous tubule

A
  • Lamina/tunica propria outer):
    • Myoid cells
    • Collagen
  • Basement membrane
  • Seminiferous / Complex stratified epithelium
    • Sertoli/supporting cells
    • Spermatogenic cells
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12
Q

Myoid cells

A

flat, elongated smooth-muscle-like cells whose contraction moves sperm & fluid ino the excurrent duct system

(flat nucleus above mouse arrow)

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13
Q

Describe seminiferous / complex stratified epithelium of the seminiferous tubule

A

One single layer of sertoli cells surround multiple layers of spermatogenic cells

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14
Q

Sertoli / Supporting / Sustentacular cells’ functions

A
  • Gives structural organization to the tubules
    • Extends from the basement membrane to the luminal surface of the seminiferous epithelium
      • Doesn’t replicate after puberty
  • Support/nurse maturing sperm cells
  • Phagocytose unneeded cytoplasmic portion of developing sperm and any messed up spermatogenic cells
  • Forms blood-testis barrier by forming tight junctions between Sertoli cells dividing the epithelium into basal and adluminal compartments
  • Exocrine & endocrine secretions - androgen-binding protein, estrogen, inhibin, MIF, growth factors
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15
Q

Spermatogenic cells characteristics

A
  • Replicates & differentiates into mature sperm
  • Organized in poorly dfined layers of progressive development:
    • Spermatogonia (most immature) rests on basal lamina
    • Spermatids (most mature) attached to apical portion of the Sertoli cells, where they border the tubule lumen
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16
Q

5 types of spermatogenic cells from immature to most mature

A

Spermatogonia (most immature)

Primary spermatocytes

Secondary spermatocytes

Spermatids

Spermatozoa (z last letter of alphabet!)

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17
Q

3 phases of spermatogenesis

A

1) Mitosis: spermatogonia self-replicate and differentiate into primary spermatocyte

2) Two rounds of Meiosis:

​​primary spermatocyte

> 2 secondary spermatocytes

> 4 spermatids

3) Spermiogenesis: spermatids transform into spermatozoa

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18
Q

The most mature form of sperm that is still within the seminiferous tubule epithelium is ___.

At what point does the thick cytoplasmic bridge connecting them disintegrate?

A

Spermatids

Bridge doesn’t disintegrate until released from epithelium

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19
Q

What is the function of the cytoplasmic bridge?

A
  • Ensures synchronous development
  • Allows free cytoplasmic communication among cells
  • Allows sharing of gene products among haploid cells
    • –> So they can have the proteins and RNAs encoded by the complete diploid genome
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20
Q

Spermatogonia appearance

A
  • Large
  • Round nucleus w diff patterns of chromatin
    • Don’t have to recognize, but there are 3 types (Type A dark, type A pale, and type B) because they undergo asymmetric cell division (shown among the 3 in the photo).
  • In contact with the basal lamina
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21
Q

Primary spermatocyte appearance

A
  • Largest germ cell; above spermatogonia
  • Spherical or ovoid
  • Large, round nucleus w strands of heterochromatin
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22
Q

These will divide and differentiate into

A

primary spermatocytes

because this is spermatogonia

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23
Q

These will under go ____ to produce ___

A

These are primary spermatocytes - they will undergo first meiosis to produce 2 secondary spermatocytes

Introduces genetic variation (by chromosomal crossover and random inclusion of either parental chromosomes) to increase genetic variability of the gamete.

24
Q

Secondary spermatocytes appearance

A

Seldom seen in histological preparations because they immediately enter and complete teh second meiotic division! Don thave to recognize

25
Q

These will undergo ___ to produce ___

A

These are spermatids and they will undergo spermiogenesis (structural changes) to become spermatozoa

26
Q

Early vs late spermatids

A

Early: small; round nuclei w condensed chromatin

Late: elongated nucleus; tail; on the apical portion of Sertoli cells, bording lumen of tubule

27
Q

Spermiogenesis

A

transforms spermatids to spermatozoa through 4 overlapping processes:

  • Nuclear condensation & elongation
  • Acrosome formation
  • Flagellum formation
  • Cytoplasm reduction : elimination of cytoplasm by Sertoli cells and release into the lumen of seminiferous tubules
    • <em>Spermiation</em>: release of spermatozoa to the lumen; determines how much sperm ends up in semen
28
Q

In the release of spermatozoa into the lumen, much of the cytoplasmic portion (residual body)

A

that cytoplasmic bridge holding them together is phagocytosed by sertoli cells

pictured w mouse arrow: free spermatozoa in lumen

29
Q

When do spermatozoa become motile?

A

They develop the capability to move and fertilize in the epdidymis , where they are stored at the distal portion before ejaculation

30
Q

Spermatozoa survival in male vs female reproductive system

A

spermatozoa live for wks in male excurrent duct system

survives 2-3 days in female reproductive tract

31
Q

Endocrine secretions of Sertoli Cells

A
  • Estradiol
    • Aromatase in Sertoli cells ( in neonatal and prepubertal mammals) converts testosterone to estradiol to regulate spermatogenesis and to inhibit testosterone production by Leydig cells
  • Inhibin B provide negative feedback on gonadotroph’s FSH synthesis and release from the adenohypophysis
  • Mullerian-inhibiting factor (MIF) causes regression of embryonic mullerian ducts
    • Inhibits development of female reproductive tract
  • Growth factors (GDNF & stem cell factor): maintain the number of spermatogonia
32
Q

Appearance of sertoli cells under light microscope

A
  • OVOID or TRIANGULAR NUCLEUS
    • large & lightly stained
    • may have 1 or more deep infoldings
    • Prominent nucleolus
  • Tall, columnar cell
33
Q

Exocrine secretions of the sertoli cells

A

Fluid: facilitates passage of maturing sperm along teh seminiferous tubules to the itnra-testicular ducts

Androgen-binding protein (ABP): binds testosterone and makes it less lipophilic & highly concentrated within the luminal fluid of the seminiferous tubules to stimulate sperm development

34
Q

Appearance of sertoli cells under electron microscope:

A
  • extensive sER, lipid droplets
  • Lots of mitochondria
  • Well-developed rough ER & Golgi
  • Lateral processes surrounding the adjacent spermatogenic cells
  • Tight junctions
35
Q

What are teh arrows poitning at

A

the tight jxns between two sertoli cells

36
Q

____ divides the epithelium into ___ and ____ compartments.

What type of cells are restricted to each compartment?

A

Tight jxns between Sertoli cells divide the epithelium into basal and adluminal compartments.

Basal compartments = spermatogonia & early primary spermatocytes

Adluminal compartments = everything else

37
Q

When early spermatocytes pass through the tight jxn to move from the basal to the adluminal compartment, is there a breakdown of the blood-testis barrier?

A

No - otherwise, you’d see spermatids in the blood

What happens is that the sertoli cells form new tight junctions below the newly formed spermatocytes, followed by breakdown of the junction above them

38
Q

Meiosis & spermiogenesis occur in which compartment

A

Adluminal

39
Q

Blood-testis barrier

A
  • Physiologic division formed by tight jxns within seminiferous epithelium with respect to ionic, aa, carbs,a nd proteins.
    • –> luminal fluid is diff from blood plasma & testicular lymph
    • –> isolates the genetically different and thus antigenic haploid germ cells from the immune system
40
Q

Temperature regulation of the testis to protect spermatogenesis

A
  • Cremaster reflex: contraction & relaxation of the cremaster (skeletal) muscle to bring the testes towards or away from the heat of the body
  • Col temperature causes the dartos (smooth) muscle to contract so the scrotum wrinkles to regulate heat loss
    • Smooth = striations
  • The testicular artery is surrounded by the pampiniform venous plexus (which is cooler blood)
41
Q

What kidn of cells are the top left two Y’s pointing at?

A

Top is pointing at the interstitium –> Leydig cells

Bottom one has that dark nucleolus–> Sertoli cells

42
Q

Wheres the Sertoli cell here?

A

Dark nucleolus

43
Q

Recap on seminiferous epithelium

A
44
Q

Cryptochordism

A

Undescended testes - testes temp is the same as body temp, which will degenerate most spermatogenic cells (except spermatogonia)

–> only see interstitial structures

45
Q

Why do the veins of the pampiniform plexus have such thick smooth muscle structure?

A

It has to propel the blood against gravity back up into the abdominal veins from the testes

46
Q

What is this

A

testicular artery (center) surrounded by pampiniform veins

47
Q

is this cremaster or dartos?

A

cremaster because it’s skeletal muscle (nucleus in periphery, striations)

48
Q
A

Testis

49
Q
A

Tunica albuginea

50
Q
A

spermatogonium

51
Q
A

primary spermatocyte

52
Q
A

Sertoli cell

53
Q
A

Spermatid

54
Q
A

Spermatozoa

55
Q
A

myoid

56
Q
A

leydig

Histo (20 decks)

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