Female reproductive
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Lecture 3: Female reproductive tract,
ovary anatomy and physiology
Outline:
¾ female
f
l reproductive
d ti ttractt
¾ review of oogenesis
¾ anatomy of the ovary and
ovarian follicle
¾ cell types- form and function
rainbow trout
Fish reproductive tract diversity
female blue shark
female red snapper
Oogenesis
¾ process beginning with the primordial germ cell (PGC) and
ending after fertilization of the egg (formation of second
polar
l b
body)
d )
¾ PGCs differentiate into oogonia in female, which multiply
by mitosis
¾ oogonia begin meiosis and become oocytes
¾ meiosis consists of 2 series of nuclear events (each with
4 phasesphases prophase,
prophase metaphase
metaphase, anaphase,
anaphase and
telophase) that reduces the oocyte chromosome number
by half (from 2n to n)
¾ meiosis
i i proceeds
d iin th
the oocyte
t until
til early
l prophase
h
where
h
it arrests until final oocyte maturation
primordial germ cell
oogonium
oocyte
egg
llate
t juvenile
j
il rainbow
i b
trout ovarian fragment
Anatomy of the Fish Ovarian Follicle
Blood Vessel
Fibroblast
Granulosa
Cells
Special
Thecal Cell
Vitelline Envelope
Thecal Layer
Basement
Membrane
Transmission electron micrograph showing
section through outer edge of a maturing winter
flounder ovarian follicle
c – oocyte cytoplasm
ca- cortical alveolus
f granulosa
fl
cellll nucleus
l
v- vitelline envelope
y- yolk body
Ovarian Follicle Cells- form & function
¾ oocyte - is the germ cell located within
the ovarian follicle
¾ carries
i th
the ffemale
l genetic
ti ttemplate
l t
¾ site of maternal mRNA synthesis
¾ in
i allll species
i some amountt off yolk
lk iis
deposited within the cytoplasm
O
Oogenesis
i in
i th
the rainbow
i b
ttroutt
early juvenile rainbow trout showing paired ovaries
Rainbow trout ovarian histology
showing early phases
Late perinucleolus
Cortical alveoli
Late
ate ooge
oogenesis
es s in tthe
e rainbow
a bo
trout ovary
Rainbow trout ovarian histology
showing late phases
Yolk body
Mature
Anatomy of the Fish Ovarian Follicle
Blood Vessel
Fibroblast
Granulosa
Cells
Special
Thecal Cell
Vitelline Envelope
Thecal Layer
Basement
Membrane
Ovarian Follicle Cells- form & function
¾ granulosa cells - single layer of somatic cells
that immediately surround the oocyte
¾ intimate contact with the oocyte occurs;
vitelline envelope and gap junctions
¾ site of estrogen synthesis during early
oogenesis, then switch to progestin synthesis
at final maturation
Scanning electron micrographs of winter
g oocytey
flounder ovarian follicle showing
granulosa cell interface
F- granulosa cell layer
Y- yolk body
Two-cell model for sex steroid
biosynthesis in the fish ovarian follicle
Ovary
theca
granulosa
testosterone
OH
aromatase
17 β -estradiol
HO
17 β -estradiol
estradiol
Flowchart of Gonadal Steroid Biosynthesis in Fishes
Ovarian Follicle Cells- form & function
¾ thecal cells - mixture of cell types found on
top of the granulosa cell layer; composed of
special (steroidogenic) thecal cells,
fibroblasts and endothelial cells
fibroblasts,
¾ this layer contains the blood and nervous
supply to the ovarian follicle
¾ special thecal cells contain gonadotropin
receptors
p
¾ important for synthesis of sex steroid
intermediates (precursors)
Transmission electron micrographs
g the cell types
yp in the p
periphery
p y of
showing
the winter flounder ovarian follicle
b – basement membrane
f- g
granulosa cell
s- surface epithelium
t- thecal cell
v-vitelline envelope
Flowchart of Gonadal Steroid Biosynthesis in Fishes
Brain-pituitary-gonad axis
