Animal Science 434 The Follicular Phase of the
- Slides: 53
Animal Science 434 The Follicular Phase of the Estrous Cycle
Hypothalamus Progesterone (-) Gn. RH Estradiol (-, +) Anterior Pituitary Inhibin (-) LH, FSH LH CL Estradiol LH, FSH Ovary Follicle
Tonic and Preovulatory Surge of Gn. RH
Hypothalamus Progesterone (-) Gn. RH Estradiol (-) Anterior Pituitary Inhibin (-) LH, FSH LH CL Estradiol LH, FSH Ovary Follicle
Steps Leading to the Preovulatory LH Surge P from Cl 4 Gn. RH FSH and LH Inhibin Proestrual Follicular Development Estradiol to threshold FSH Preovulatory LH surge
Relationship of Hypothalamus, Anterior Pituitary and Ovary In the Absence of Progesterone
Tonic and Preovulatory Surge of Gn. RH
Hormone Changes During the Folliclular Phase Progesterone LH FSH Estradiol
Follicle Progression
Growth and Atresia of Follicles
Follicular Growth Gonadotropin Independent Small Antral Follicle Recruitment Initiated by FSH
Progesterone FSH Inhibin LH FSH Inhibin E 2 LH Deviation!!!
Folliclular Waves in Cattle
Follicular Waves
Follicular Waves
Growing Phase • Initial growth (recruitment) is under influence of FSH • Inhibin secreted to decrease FSH and development of subordinate follicles (estrogen also; selection) • Dominant follicle becomes less dependent on FSH for growth • FSH induces LH receptors in granulosa • Dominant follicle produces estradiol androgens in response to LH and FSH • Androgens, lack of FSH may cause subordinate follicles to become atretic (dominance)
Static Phase • Inhibin production stops • FSH increase stimulates follicular wave • Estradiol from dominant follicle decreases androgens increase, this may initiate atresia of dominant follicle
Regressing Phase • Dominant follicle becomes atretic and looses steroidogenic capability
Follicular Waves
Growing Phase • Initial growth (recruitment) is under influence of FSH • Inhibin secreted to decrease FSH and development of subordinate follicles (estrogen also; selection) • Dominant follicle becomes less dependent on FSH for growth • FSH induces LH receptors in granulosa • Dominant follicle produces estradiol androgens in response to LH and FSH • Androgens, lack of FSH may cause subordinate follicles to become atretic (dominance)
Growing Phase • LH continues to increase in response to estradiol positive feedback in the absence of progesterone • Dominant follicle increases in size and estrogen production • LH surge occurs to trigger ovulation of the dominant follicle
Hormone Changes During the Folliclular Phase Follicular Phase Progesterone LH FSH Estradiol Ovulation
Follicular Size Two Follicular Waves Dominance Atresia Ovulation Selection (Deviation) Recruitment Ovulation 10 Day After Ovulation 21
Follicular Size Three Follicular Waves Ovulation 9 16 Day After Ovulation 21
Follicular Waves
Fate of follicles and oocytes. Total # of follicles At birth 100, 000 12 months 75, 000 4 -6 years 21, 000 Aged cow 2, 500 100 Days of Gestation 2. 9 million Follicles grow to tertiary characteristic and degenerate. Maximum number of oocytes ovulated for a cow 17 cycles/year x 8 year = 136 oocytes ovulated/lifespan Can increase with superovulation with FSH to stimulate the rescue of follicles which would have undergone atresia
Gonadotropin Action Within the Follicle
Theca Interna Granulosa
LH Theca Interna Receptor Selection Dominant Follicle Express LH Receptor c. AMP Cholesterol PKA Testosterone LH Receptor c. AMP Testosterone c. AMP PKA Granulosa Estradiol Bloo d FSH
Ovulation
Germinal Epithelium Tunica Albuginea Theca Externa Theca Interna Basement Membrane Granulosa
Blocking of these events in the follicle prevents ovulation. • protein synthesis • steroid synthesis • prostaglandin synthesis • plasminogen activator synthesis
Pathways of Ovulation LH increased cyclic AMP Mature follicle Increased blood flow to follicle Protein synthesis Cumulus cell production (cellular differentiation) of hyaluronic acid and proteins Steroid biosynthesis Prostaglandin biosynthesis Cumulus expansion (PGE 2 and PGF 2 ) Progesterone Separation of cumulus and oocyte from granulosa cells Inactive Collagenase (theca) Plasminogen activator (granulosa) Plasmin (protease) Active Collagenase Breakdown of theca and tunica albuginea collagen and tensile strength of follicle wall PGF stimulates smooth muscle contractions around follicle Increased vascular permeability of follicle Follicle ruptures with only a slight increase in follicular pressure Expulsion of follicular contents Increased plasminogen in tissue and follicular fluid
Preovulatory LH Surge Cumulus Expansion Oocyte Separates From Follicular Wall Ovulation
Cumulus Expansion Hyaluronic Acid and Protein Production Unexpanded Expanded
Cumulus and Oocyte Separation
Preovulatory LH Surge Cumulus Expansion Protein Synthesis in and around Follicle Plasminogen Activator Collagenase (inactive) Progesterone Increased Blood Flow to Ovary and Follicle Vascular Prostaglandin Permeability Synthesis PGE and PGF Plasmin Oocyte Collagenase (active) Separates Follicular Wall From Weakens Follicular Wall Ovulation Plasminogen Contraction of Smooth Muscle
Types of Ovulators
Spontaneous Ovulators
Induced Ovulators
Induced Ovulators Nerve endings sensing copulation Copulation Sensory Neurons Penis
Hypothalamus Blood LH Time (hr) Gn. RH Posterior Pit. Stimulation LH Anterior Pit. Spinal Chord
LH Nerve endings sensing copulation Copulation Sensory Neurons Penis
Cats • Induced Ovulators • Single copulation – Only works 50% of the time • Multiple copulations – Higher LH surge
Spontaneous Ovulators • Retain some neural control of ovulation – heifers can alter the timing of the LH surge by clitoral stimulation – human rape cases result in higher than expected pregnancy rates
Manipulating Ovulation • will cover latter in class
Oogenesis Migration to germinal ridge Mitotic divisions Primordial Germ Cells Oogonia Initiation of Meiosis Interphase DNA synthesis Meiotic prophase begins Gonadotropin Independent Gonadotropin Dependent Primary Oocyte Growth Follicle Cells Prophase of Meiosis leptotene zygotene pachytene diplotene dictyotene Meiotic Arrest zona pellucida formation m. RNA production protein synthesis cortical granule formation nuclear maturation cytoplasmic maturation
Fetal Oocyte Development Mitosis Fertilization Meiosis Birth Cow 280 d Sow 114 d Mouse 19 d
Corona Radiata Oocyte Cortical Granules Zona Pellucida Gap Junctions Cortical Granules
During Oocyte Growth and Before the LH Surge • OMI - Oocyte Maturation Inhibitor c. AMP OMI c. AMP GV PKA pre-MPF • MPF - Maturation promoting factor • GV - germinal vesicle (nucleus) Gap Junctions Allow Cell to Cell Communication!
The LH Surge c. AMP GVBD PKA GV pre-MPF Gap Junctions are Destroyed! Resumption of Meiosis
LH Surge 4 N Primary Oocyte Ovulation • Dog • Fox Resumption of Meiosis First polar body emitted, arrest at metaphase II of meiosis 4 N Sperm Penetration Secondary Oocyte • Dog • Fox 2 N Ovulation (most species) Zygote (pronucleate egg) N N 2 N Sperm Penetration
- Follicular phase
- Follicular adenoma
- Thyroid gland
- Follicular cells
- Subcapsular sinus
- Allah adalah kasih dan sumber kasih
- Anatomy team 434
- Astm d4685
- Nodular goiter
- Histology thyroid gland
- Pituitary gland inferior view
- Brown tumor
- Principal cells location
- Hormones
- Follicular cells of thyroid gland
- Rocky mountain fever
- Anatomy team 434
- Ece 434
- Follicular conjunctivitis
- Oogenesis and follicular development
- Plot
- Ameloblastoma follicular
- Ece 434
- Ece 434
- 434 x 2
- Follicular development diagram
- Follicular study
- Ece 434
- Follicular nonhodgkins lymphoma
- Science science science
- Normal phase vs reverse phase chromatography
- Hplc reverse phase vs normal phase
- Mobile phase and stationary phase
- Hplc definition
- Normal phase vs reverse phase chromatography
- Line vs phase voltage
- Which detector used in hplc
- In a ∆-connected source feeding a y-connected load
- Broad phase vs narrow phase
- Animal vs plant cell
- Venn diagram plant vs animal cells
- Animal rights versus animal welfare
- Animal nutrition grade 11
- Animal science final exam
- Colorado animal science curriculum
- Animal science
- Chinese water dragon anatomy
- Animal science career cluster
- Animal science merit badge worksheet
- Project proposal in animal science
- Advanced animal science
- Advanced animal science
- Damron introduction to animal science download
- Adv animal science