Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

vertebrate development > gametogenesis & sex determination > Flashcards

gametogenesis & sex determination Flashcards

1
Q

where are sperm produced

A

seminiferous tubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

where are oocytes produced

A

cortex of the ovary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the two ways to form an early germ cell

A

predetermine/ autonomous

and induced formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what do BMPs do and how do they do it

A

Prevent germ cell differentiation into somatic cells.

Smad signalling to the nucleus, makes fragilis and Blimp1 proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is Blimp1 and what cells does it act on

A

a transcription factor activating Nanos and maintaining Nanog expression.
it acts on Primordial Germ Cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what does Nanos do?

A

limits differentiation to somatic cells and stops apoptosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

the SRY gene is a member of which family of transcription factors? which protein does it turn on?

A

Sox family. Sox9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is Sox9, give three things it does

A

an autosomal transcription factor expressed on in a positive feedback loop with its own gene (gonad formation)

it blocks ovary formation by the genital ridge - stops function of the paracrine Wt/beta catenin pathway

activates expression of anti-mullerian hormone

activates expression of FGF9 (in +ve feedback loop with sox9) in the genital ridge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what three genes are involved in the positive feedback loop of male development

A

SRY -> SOX9 -> FGF9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does Wnt4 do in females

A

a paracrine signal that remains high in the female genital ridge but is lost in males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

where are oocytes contained

A

follicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the molecular components that define germ cells

A

Vasa, Nanos, Tudor, Piwi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what do Vasa proteins do?

A

bind mRNA and increase translation efficiency of germ cell specific messages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what do Nanos proteins do

A

bind mRNA and decreases translation efficiency of germ cell specific messages - present in somatic cells (mesoderm/ ectoderm/ endoderm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is predetermined (autonomous) formation of germ cells

A

egg is fertilised, embryo divides, at some point in early development a small group of cells is earmarked- here the germ cells are defined by the segregation of Vasa/ Nanos/ Tudor/ Piwi which become concentrated in the cytoplasm of the egg (the germ plasm) (no external signal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what animals have predetermined formation of germ cells

A

Nematodes, Insects, Fish, Frogs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what type of germ cell formation do mammals have

A

induced formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what structure of the embryo forms the testis/ovary

A

the genital ridge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what evidence is there against predetermination in humans

A

germ cells appear after gastrulation (day 13-19)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are P granules

A 
a class of perinuclear RNA granules specific to the germ line - Complexes of RNA and proteins that help to form the gonads.
"germ granules"
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what do P granules do

A

they contain inhibitors of gene transcription and prevent the germ cells differentiation into somatic cells - concentrated into P cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the location of PGCs in the human embryo (day24)

A

found in yolk sac (endodermal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what does every cell in our body start life as

A

pluripotent epiblast cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are the pluripotent markers in PGCs

A

Nanog and Sox2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what causes posterior epiblast cells to become PGCs
BMPs
26
why do PGCs migrate to areas outside the embryo proper (humans&mouse to the yolk sac)
To separate these cells from paracrine differentiative signals in the rapidly forming embryo
27
what does E-cadherin do in germ cell development
it keeps the PGCs together as a group and stops their migration out of the yolk sac and being lost
28
what is fragilis
a plasma membrane receptor for adhesion with E cadherin (and others)
29
Induction of mouse germ cell development is done by what group of proteins
Bone Morphogenetic Proteins BMPs - BMP4, BMP8b, BMP2
30
where do BMPs act and on what cells
extraembryonic epiblast cells
31
what protein is responsible for specification in mouse germ cell development
Blimp1
32
what does Blimp1 do and how
Prevent germ cell differentiation into somatic cells. | By transcriptional regulation - activating Nanos and maintaining Nanog
33
if you remove what protein you fail to get PGCs (in an induced formation)
BMP(4)
34
what proteins are responsible for PGCs migration to the genital ridge
Nanos3, Kit and Dead end1
35
what do Nanos3 and Dead end1 do during migration
prevent apoptosis (by binding to mRNAs)
36
what does Kit do during migration of PGCs?
prevents apoptosis, stimulates proliferation, and may help line path to gonad (no kit = sterile)
37
what defines the outcome of the PGCs (male/ female)
the Y chromosome 'gene' expression by the genital ridges and surrounding tissues (ie the somatic cells)
38
What is the SRY gene? - major function?
sex determining region of the Y chromosome. (a transcription factor - The mammalian Testis Determining Factor TDF
39
which is the shared evolutionary male gene
Sox9
40
what is Fgf9? give three functions
- Paracrine signalling molecule formed by the somatic cells of the genital ridge causes proliferation and differentiation of some genital ridge cells to form Sertoli cells and formation of chords of cells - gives the tubular structure of the testis later Represses (with Sox9) the Wnt/B-catenin path so blocks ovary formation Coordinates differentiation pathway of PGCs
41
where is testosterone produced
The interstitial cells between the seminiferous tubules in the testes
42
What does the Wolffian duct develop into?
Vas deferens, epididymis, seminal vesicle
43
loss of the androgen receptor results in what
female appearance but with retained testes
44
what three proteins lead to female development
Wnt, beta-catenin, follistatin
45
in some reptiles expression of Sox9 is related to what
temperature | – Alligator eggs incubated at 33degreesC 100% male, 30degreesC 100% female
46
in birds and some reptiles high levels of what drives expression of Sox9 -
high levels of DMRT1 present on the Z chromosome drive expression of Sox9 - a gene dosage system (male ZZ, female ZW)
47
what does the Mullerian duct develop into
the ovarian ducts, uterus cervix and top of vagina
48
the fate of the PGCs depend upon the gender of the ______ not that of the ______
The fate of the PGCs depends upon the gender of the ridge not that of the PGCs
49
when do quiescent PGCs restart meiosis (in males)
puberty
50
what is induced formation of early germ cells
the germ cell formation occurs after implantation into the uterus and Vasa/ Nanos/ Tudor and Piwi are not present in the egg but their expression is induced by signalling molecules (paracrine molecules) from neighbouring cells
51
describe the germ cell creation in C.elegans
Vasa/ Nanos/ Tudor and Piwi are concentration in P granules, these are retained in the P cells (P1-P4) in the germ plasm - p granules are markers for the germ plasm to segregate to the p1 then p2 then p3 then p4 cell during each division
52
how was induction (formation of germ cells) proved
* The PGCs form in the posterior (back) part of the epiblast – if you replace these cells in a embryo with anterior epiblast cells (front) from a embryo expressing GFP - these new cells will go on to form GFP expressing PGCs * If you remove BMP(4) the inducer – by gene knockout- you fail to get PGCs
53
what are the main factors for sexual differentiation in males and females
Nanos2 in males | Stra8 in females
54
how many cells are Blimp1 positive in mouse at embryonic day 6.5
6
55
in you inject a DNA solution containing the SRY gene into a XX female mouse what happens
you get a male mouse
56
where is SRY expressed
in somatic cells of the genital ridge
57
what does Sox9 do at the genital ridge
blocks ovary formation by stopping function of the paracrine Wnt/beta-catenin pathway
58
in mammals what drives Sox9 expression
SRY gene
59
sertoli cells induce differentiation of what in males
differentiation of mesenchymal cells in the genital ridge to form interstitial cells- which produce testosterone
60
what are two things does testosterone do in the embryo
* Allows growth of the Wolffian (mesonephric) duct to form the epididymis and the vas deferens * Drives the secondary sex determinants
61
what remains high in the female genital ridge but is lost in males
Wnt4
62
what does follistatin do in the genital ridge
induces the genital ridge to form an epithelium (granulosa cells) and surrounding the PGCs forming follicles
63
over expression of beta catenin in males causes what
an ovary to form
64
what has high levels in the male genital ridge but is reduced in the female
FGF9
65
what causes the female PGCs to enter meiosis
Retinoic acid diffuses into the PGCs and causes expression of Stra8 (the 'master switch' for meiosis)
66
where is retinoic acid made
in the mesonephros
67
what is the the principal excretory organ during early human embryonic life (4—8 weeks).
Mesonephros
68
where does the gonad develop
on the medial surface of the mesonephros
69
what does the mesonephros form in males and females
forms parts of the epididymis and vas deferens in males, but regresses, in females
70
What stops PCGs in male fetal testis entering meiosis?
Stra8 levels do not rise in male PCGs because fiboblast growth factor 9 (FGF9) is produced by male gonadal ridge cells and a) Induces Cyp26b1 which degrades RA before it reaches the PCGs b) Represses Stra8 expression – so inhibits meiosis entry
71
what is Cytochrome P26b1 (Cyp26b1)
an enzyme involved in the degradation of retinoic acid - absent in females, only present in male gonads. driven by Sox9/FGF9
72
both sexes make retinoic acid but it is _______________ in male gonads
- Both sexes make RA but is only metabolised in male gonads
73
Loss of Cyp26B1 enzyme in males results in what
male PGCs entering meiosis in utero this results in an infertile male (has testis but no sperm)

vertebrate development (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions