Biology Reference
In-Depth Information
A
Fly—
Drosophila melanogaster
Inner sheath cell
Cytoblast
(a)
Stage 2
Pole plasm
(c)
Germarium
Mature cyst
Nuclei
SSC
GSC
Cap cell
p
a
(b)
Stage 5
Pole cells
Terminal
filament
Somatic cells
Niche
Escort cell
16-cell cyst
Follicle cell
a
p
B
Fish—
Danio rerio
(a)
4-cell stage
(b)
10 somite stage
(c)
21 hpf
Midline
and
somites
Germ plasm
Yolk
Gonad region
PGCs
Blastomere
PGCs
animal view
Dorsal view
Lateral view
C
Mouse—
Mus musculus
Theca cells
Granulosa cells
LH
Secondary
oocyte
(a)
E6.0 and E7.25
(b)
Gametogenesis
CI
Arrested
Primary oocytes
TE
FSH
EXE
VE
Oogonia
oocyte
Meiosis I and meiosis II
Ovulation
PE
ZP
PGCs
Folliculogenesis
Self-renewal
Maturation
Meiosis I Meiosis II
Sperm
Spermatogonia
pPGCs
Epiblast
PGCs
Spermatid
Primary
and
secondary
Sertoli cell
spermatocytes
Figure 4.1
(A) Schematic representation of germline development in D. melanogaster.
(A(a)) The maternally provided pole plasm is localized to the posterior (p) of the
developing embryo; a (anterior) (A(b)) Following cellularization, cells located at the
posterior of the embryo that inherit the pole plasm become the pole cells, or PGCs.
(A(c)) The GSC are maintained by signals provided by cells in the niche, while germline
