Transcript Powerpoint_12a_13

The Luteal Phase of the Estrous
and Menstrual Cycle
John Parrish
• steroid synthesis
– progesterone
• collagenase
– theca interna
• present 1-3 days
following ovulation
•
blood vessels in
follicle wall rupture
• walls collapse
• cells intermix
• old basement
membrane becomes
connective tissue of
CL
• increases in size
– papilla forms
• composed of cells
from the granulosa
and theca interna
• progesterone
production
increases
• a small cavity may
be present where
the folliclular
antrum was
present
Luteal Tissue
• Large cells from granulosa
• Small cells from the theca interna
Mitochondria
Secretory
Granules
- Oxytocin
- Relaxin
Functional Capability of CL
• the number of luteal cells
– large cells undergo hypertrophy (3 fold)
– small cells undergo hyperplasia (5 fold)
• vascularization of CL
– Initiated by angiogenic factors from
follicle
– Vascularity effects CL steroid synthesis
and delivery of hormones
• Insufficient CL function
– Failure to maintain pregnancy
– Important in domestic animals
Blocks Estrus
Negative Feedback
Progesterone Targets
Aveolar
Development
Molecular Mechanism of LH on Luteal Cell
(cAMP second messenger)
LH
G
Receptor
Plasma Membrane
Adenylate Cyclase
cAMP
PKA
Progesterone
ATP
R
cAMP
S-ER
C
Steroid Synthesis
(+ PO4)
Mitochondria
Cholesterol
Pregnenolone
Histones
Cholesterol
Protein
Synthesis
(Enzymes)
Synthesis
R-ER
Protein
mRNA
Nucleus
DNA
Molecular Mechanism of LH on Luteal Cell
(cAMP second messenger)
Chol
LH
LDL
G
Receptor
Plasma Membrane
Adenylate Cyclase
cAMP
PKA
Progesterone
ATP
R
cAMP
S-ER
C
Steroid Synthesis
(+ PO4)
Cholesterol
Cholesterol
Protein
R-ER
Synthesis
(Enzymes)
Protein Synthesis
LDL
Chol-Ester
LDL
Mitochondria
Pregnenolone
Chol
Chol
Esterase
Luteolysis
• Uterus
• PGF2a
• Oxytocin
Luteolysis
in Cows,
Ewes,
Sows CL
Normal
Uterus
CL Normal Lifespan
Total
Hysterectomy
CL Lifespan
Longer
Similar to
Gestation Length
Contralateral
Hysterectomy
CL Normal Lifespan
Ipsilateral
Hysterectomy
CL Lifespan
Longer
>35 days
Luteolysis
• Uterus
• PGF2a
• Oxytocin
Prostaglandin F2a Control of Luteolysis
Uterine Horn
Prostaglandin synthesis
by uterine endometrium
is released into the
uterine vein.
Progesterone from
CL stimulates
production of
uterine PGF2a after
day 15 in cow
Corpus
Luteum
Oviduct
Ovary
Uterine
Vein
Ovarian Pedicle
PGF
PGF2a is picked up by
ovarian artery through
counter current exchange
and delivered back to the
ovary where it causes
lysis of the CL
PGF into Artery
Uterine Artery
CL
Normal
Uterus
CL Normal
Lifespan
Total
Hysterectomy
CL Maintained
Luteolysis
Mare
Contralateral
Hysterectomy
Ipsilateral
Hysterectomy
50% of CL’s
Maintained
50% of CL’s
Maintained
Blood Supply to Uterus and Ovary in the Mare
PGF Not Effective (Sow)
PGF Not Effective (Cow, Ewe, Mare)
Luteolysis
• Uterus
• PGF2a
• Oxytocin
Relationship of Oxytocin and PGF2a
Posterior
Pituitary
Anterior
Pituitary
CL
Oxytocin
PGF2a
Ovary
Uterus
Luteolysis
• decreased blood flow
• cellular response
– apoptosis
– progesterone synthesis
• Immune response
– Lymphocytes
– Macrophages
Molecular Mechanism of PGF
(Ca2+ Second Messenger)
Ca2+
Plasma
Membrane
Receptor
PGF
G-protein
PIP2
PLC
DAG
IP3
Protein
Kinase C
Ca2+
R
Cholesterol
Ca2+
Endoplasmic Reticulum
Apoptosis
Progesterone
Plasma Membrane
Luteolysis
• decreased blood flow
• cellular response
– apoptosis
– progesterone synthesis
• Immune response
– Lymphocytes
– Macrophages
Menstrual Cycle
Anterior
Pituitary
Hormones
LH
FSH
Progesterone
Ovarian
Hormones
Estradiol
Follicle
Ovulation
Corpus Luteum
Corpus
Albicans
Ovary
Recruitment
Dominance
Selection
Recruitment
Uterine
Endometrium
2
4
6
8
10 12 14 16 18 20 22 24 26 28
2
Luteolysis in the Primate
• Does not require the uterus
• CL lifespan in the human is 12-14 days
unless pregnancy occurs
– In the absence of pregnancy, CL self destructs
– Possible intra-ovarian oxytocin receptors and
PGF2a production
• Menstruation
– Drop in P4 and E2
– Endometrial PGF2a, vasoconstriction, necrosis
– Endometrial inflammation and tissue
degeneration