Organismal Development Part 4

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Organismal DevelopmentPart 4

• Female Animals

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Female Reproductive Anatomy
Oviduct
Ovaries
Follicles
Corpus luteum
Uterine wall
Uterus
Endometrium
Cervix
Vagina
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Oogenesis in the ovaries
Ovary
Primary germ cell in embryo
Differentiation
Oogonium in ovary
Oogonium
Mitotic division
Primary oocyte within follicle
Primary oocyte
Completion of meiosis I and onset of meiosis II
Growing follicle
Secondary oocyte
First polar body
Ovulation
Mature follicle
Entry of sperm triggers completion of meiosis II
Ruptured follicle
Second polar body
Ovum
Ovulated secondary oocyte
Corpus luteum
Degen- erating corpus luteum
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Female Reproductive Cycle in Humans
Control by hypothalamus
Inhibited by combination of estrogen and
progesterone
Hypothalamus
Stimulated by high levels of estrogen
GnRH
Anterior pituitary
Inhibited by low levels of estrogen
FSH
LH
Pituitary gonadotropins in blood
LH
FSH
LH surge triggers ovulation
FSH and LH stimulate follicle to grow
Ovarian cycle
Corpus luteum
Degenerating corpus luteum
Growing follicle
Mature follicle
Follicular phase
Ovulation
Luteal phase
Progesterone and estrogen secreted by corpus
luteum
Estrogen secreted by growing follicle
in increasing amounts
Peak causes LH surge
Ovarian hormones in blood
Progesterone
Estrogen
Estrogen level very low
Progesterone and estro- gen promote thickening of
endometrium
Uterine (menstrual) cycle
Endometrium
Menstrual flow phase
Proliferative phase
Secretory phase
Days
28
25
20
15
14
10
5
0
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Fertilization and Implantation if pregnancy occurs
Cleavage starts
Cleavage continues
Ovary
Fertilization occurs
The blastocyst implants
Uterus
Ovulation
Endometrium
From ovulation to implantation