Spermiogenesis

Question 1

describe how the mammalian haploid spermatid looks like (2)

Answer 1

round
unflagellated

Question 2

what is the other term for spermiogenesis

Answer 2

spermateliosis

Question 3

differentiation stage of spermatids into mature spermatozoa

Answer 3

spermiogenesis

Question 4

what functions of the sperm does spermiogenesis focus on (2)

Answer 4

motility
interaction (with the egg)

Question 5

what is the first step of spermiogenesis? where does this originate?

Answer 5

construction of the acrosomal vesicle
from the Golgi apparatus

Question 6

what is the role of the acrosome?

Answer 6

it forms a cap that covers the sperm nucleus

Question 7

as the acrosomal cap is formed, the nucleus rotates so that the cap faces the _______________ of the seminiferous tubule

Answer 7

basal lamina

Question 8

why is the roatation of the nucleus facing the basal lamina of the sem.tub. necessary?

Answer 8

because the flagellum, which is beginning to form from the centriole on the other side of the nucleus, will extend into the lumen of the seminiferous tubule

Question 9

what happens during the last stage of spermiogenesis?

Answer 9

• the nucleus FLATTENS and CONDENSES
• the remaining cytoplasm (residue) is discarded
• and the mitochondria form a ring around the base of the flagellum

Question 10

(last stage)
what happens to the nucleus (2)

Answer 10

flattens and condenses

Question 11

(last stage)
what happens to the remaining cytoplasm (residue/cytoplasmic droplet)?

Answer 11

jettisoned (discarded)

Question 12

(last stage)
what happens to the mitochondria?

Answer 12

form a ring around the base of the flagellum

Question 13

during spermiogenesis, the histones of the spermatogonia are often replaced by _________

Answer 13

sperm-specific histone variants

Question 14

what happens as sperm-specific histone variants replace the histones of the spermatogonia?

Answer 14

widespread nucleosome dissociation takes place

Question 15

info

Answer 15

during the remodeling of nucleosomes,
PGC pattern of methylation is removed and
male genome-specific pattern of methylation is established on the sperm

Question 16

as spermiogenesis ends, the histones of the haploid nucleus are eventually replaced by _________

Answer 16

protamines

Question 17

what does the replacement of the histones of the haploid nucleus to protamines result to?

Answer 17

the complete shutdown of transcription in the nucleus and
facilitates the nucleus, which leads to
- an almost crystalline structure, which will then enter the lumen of the seminiferous tubule

Question 18

info

Answer 18

the sperm continue to develop after they leave the testes

Question 19

where does the sperm reside when they are being
transported from the testes

Answer 19

in the epididymis

Question 20

what does the epididymal cells release that fuse with the sperm as they reside in the epididymis?

Answer 20

exosomes

Question 21

what do exosomes contain and what does it do to the sperm?

Answer 21

small ncRNAs and other factors that can activate and repress certain genes
- the sperm will bring these agents into the egg

Question 22

info

Answer 22

the sperm still isn’t fully mature, even when it exits the urethra

Question 23

where does the final differentiation of the sperm occur?

Answer 23

in the reproductive tract of the female

Question 24

what is in the reproductive tract that completes the differentiation of the sperm?

Answer 24

secretions from the oviducts will change the sperm cell membrane so that it can fuse with the membrane of the egg cell

Question 25

(duration in mouse) devt. from stem cell to spermatozoon: ___________ spermatogonial stages: ______________ meiosis: ______________ spermiogenesis: ____________ (takes twice as much in humans)

Answer 25

devt. from stem cell to spermatozoon: 34.5 days spermatogonial stages: 8 days meiosis: 13 days spermiogenesis: 13.5 days

Question 26

how much sperms are made in human testicles in a day? how much are release in each ejaculation?

Answer 26

about 100 million 200 million

Question 27

what happens to unused sperm? (2)

Answer 27

either resorbed or passed out of the body in urine

Question 28

how many sperms are produced in a lifetime of a human male?

Answer 28

1,000,000,000,000 to 10,000,000,000,000 sperm

Question 29

what are the features of the sperm at spermiogenesis? (3) - an _________ atop its head - the midpiece containing a ___________ - a ___________ for motility

Answer 29

acrosome ring of mitochondria flagellum

Question 30

what are the 4 phases of spermiogenesis

Answer 30

(1) golgi phase (2) cap phase (3) tail phase (4) maturation phase

Question 31

what comes after spermiogenesis?

Answer 31

spermiation

Question 32

what enzyme does the golgi apparatus release that will gather inside the future acrosome?

Answer 32

lytic enzyme

Question 33

what does the genetic material (DNA) do when protamines replace histones?

Answer 33

undergoes packaging

Question 34

when does the genetic material (DNA) undergo packaging?

Answer 34

when protamines replace histones

Question 35

what are the characteristics of the genetic material at the end of spermiogenesis? (3)

Answer 35

tightly packed highly condensed transcriptionally inactive

Question 36

what do you call the thickening and reduction of the nuclear size? (puts nuclear contents into the smallest space)

Answer 36

nuclear condensation

Question 37

what phase do you call the formation of the acrosomal cap?

Answer 37

cap phase

Question 38

the acrosomal cap forms when the golgi apparatus surrounds the __________

Answer 38

anterior of the spermatid

Question 39

what complex is the major driver for shaping the head of the developing spermatid?

Answer 39

acrosome-acroplaxome-manchette complex

Question 40

what phase do you call the elongation of microtubules on one of the centrioles of the spermatid to become the tail?

Answer 40

tail phase

Question 41

in the tail phase, what do the microtubules form?

Answer 41

axoneme

Question 42

explain the 9+2 configuration of the axonome

Answer 42

9 doublets: the core of the axonome is formed by nine microtubule doublets (a pair of microtubules, arranged side by side, one larger than the other) 2 single microtubules: located in the center of the axoneme are two single microtubules (central pair)

Question 43

The developing germ cell orients itself such that the growing tail is directed toward the ______________ of the seminiferous tubule.

Answer 43

center of the lumen

Question 44

what are the 4 parts of the finished flagellum?

Answer 44

(1) neck (2) mid piece (3) principle piece (4) tail

Question 45

(part of the flagellum) contains the two centrioles (proximal and distal) among other things

Answer 45

neck

Question 46

(part of the flagellum) consists of a sheath of ring-shaped mitochondria grouped around the axoneme to provide the energy for the flagellar movement

Answer 46

mid-piece

Question 47

(part of the flagellum) has a sheath of ring fibers around the axoneme

Answer 47

principle piece

Question 48

(part of the flagellum) consists of only the 9+2 structure of the axoneme

Answer 48

tail

Question 49

what are the two centrioles in the neck part of the flagellum?

Answer 49

proximal distal

Question 50

what is the phase where the residual cytoplasm has been disposed of?

Answer 50

maturation phase

Question 51

what is the term for the remaining cytoplasm and organelles that are removed by phagocytosis through Sertoli cells?

Answer 51

residual body of regaud

Question 52

how are the remaining cytoplasm and organelles in the maturation phase disposed of?

Answer 52

by phagocytosis through sertoli cells

Question 53

what do you call the elimination of all unnecessary cytoplasm?

Answer 53

cytoplasm reduction

Question 54

what do you call the migration of the spermatozoon to the epididymis to become a motile sperm cell?

Answer 54

spermiation

Question 55

what cells release the elongated non-motile spermatozoa into the lumen of the seminiferous tubules?

Answer 55

sertoli cells

Question 56

what cells secrete testicular fluid to aid spermatozoa to travel from the seminiferous tubules to the rete testis in the mediastinum testis?

Answer 56

sertoli cells

Question 57

what do sertoli cells secrete to aid spermatozoa to travel from the seminiferous tubules to the rete testis in the mediastinum testis?

Answer 57

testiscular fluid

Question 58

sertoli cells secrete testicular fluid to aid spermatozoa to travel from the seminiferous tubules to the _______ in the __________, to the _________, and finally to the epididymis via peristaltic contraction

Answer 58

rete testis mediastinum testis efferent ducts epididymis

Question 59

sertoli cells secrete testicular fluid to aid spermatozoa to travel from the seminiferous tubules to the rete testis in the mediastinum testis, to the efferent ducts, and finally to the epididymis via what mechanism?

Answer 59

peristaltic contraction

Question 60

what are the sperm shape of the following? - teleosts - amphibians - man and mammals - mouse and rats

Answer 60

– Spheroidal – Rod/ lancet-shaped – Spoon-shaped – Hooked-shaped

Question 61

what organisms have flagellated and non-flagellated sperms?

Answer 61

flagellated (monoflagellate) majority of vertebrates (biflagellate) toad and fish non-flagellated - ascaris - crab