The Testes Gamete Development (sperm) Hormonal Production (testosterone) Male Reproductive Biology.
Chapter 9. Hormonal Control of Reproduction Part II Female Reproductive System.
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Transcript of Chapter 9. Hormonal Control of Reproduction Part II Female Reproductive System.
Chapter 9. Hormonal Control of Reproduction Part II
Female Reproductive System
Contents
• Part 1. Structure of Ovary
• Part 2. Ovarian Hormones
• Part 3. The Menstrual Cycle
• Part 4. The Endocrinology of Pregnancy
STRUCTURE OF OVARYPart 1
4
Structure of Ovary• Fibrous capsule - tunica albuginea• Outer cortex houses developing gametes, the oocytes (卵母细胞) , within follicles (滤泡)
• Inner medulla is loose connective tissue with largest vessels and nerves
5
• Follicular phase– 1st approx 14 days but variable– Egg develops in a follicle– Stimulated by FSH– Estrogen produced
• Ovulation– Egg released from follicle (LH surge) – Egg in abdominal cavity– Picked up by fimbria ( 伞部) of fallopian tube
Ovarian Cycle
Ovarian Cycle (cont.)• Luteal phase– Postovulatory phase 14 days (more constant)– Corpus luteum develops from exploded follicle– Produces progesterone as well as estrogen• Progesterone stimulates uterus to be ready for baby
– If no pregnancy, corpus luteum degenerates into corpus albicans
Stages of Follicular Development in the Ovary
OogenesisGeneration of eggs
• Starts in fetal period– No more oocytes made after
about 7th month– Developed only to early stage
of meiosis I by birth and stops (called primary oocyte)
• 6-12 primordial oocytes each cycle selected to develop for ovulation (most die)– Only then is meiosis I
completed– Secondary oocyte is then
arrested in meiosis II• Meiosis II not completed (now
an ovum) unless sperm penetrates its plasma membrane
• Of the 4 daughter cells, only one becomes ovum (needs a lot of cytoplasm)– The other 3 become “polar
bodies”
Primordial Follicle (原始卵泡)
The primordial follicle can be identified by its single layer of follicular cells (red arrow). To the right are two atretic follicles (闭锁卵泡) (blue arrows). Notice the wavy stroma (基质) . Bar = 50 Microns
Primary Follicle(初级卵泡)
At least two layers of follicular cells identify the primary follicle (red arrow). A primordial follicle (in another plane and therefore slightly out of focus) lies alongside (blue arrow). Bar = 50 Microns
Primary Follicle
secondary follicle
The secondary follicle shows the beginning of a fluid-filled space known as the antrum (A). Notice that the oocyte proper (arrow) is embedded within the follicular cells. Bar = 50 Microns
Graafian (vesicular) Follicle
卵丘
卵母细胞
透明带
内膜层
外膜层
14
Nearly mature follicle
• Oocyte develops the zona pellucida (透明带)– Glycoprotein coat– Protective shell (egg shell)– Sperm must penetrate to fertilize the oocyte
• Thecal cells stimulated by LH to secrete androgens• Granulosa cells (with FSH influence) convert androgens to
estrogen (follicular cells called granulosa cells now)• Clear liquid gathers to form fluid-filled antrum: now a secondary
follicle• Surrounding coat of granulosa cells: corona radiata (放射冠)• Fully mature, ready to ovulate, called: ”Graafian follicle”
15
Ovulation
• Signal for ovulation is LH surge
• Ovarian wall ruptures and egg released– surrounded by its
corona radiata
corpus luteum
Progesterone from the corpus luteum maintains the uterus for implantation. Notice the fullness of the granulosa luteal cells (GL) and positioning of the theca luteal cells (TL). Bar = 50 Microns
corpus luteum
Corpus albicans (白体)
19
Fallopian (uterine) tubesFimbriae (fingers) pick up egg
Beating cilia and muscular peristalsis propel egg to uterus
Empties into superior part of uterus*
____Fallopian tubes__
Fimbriae *
Cross section through entire tube
Enlargement of mucosa layer showing ciliated columnar epithelium
PID
Part 2 Hormones Secreted from Ovary
Cases: Imbalanced Sex Steroids• Joanna Jones, 24 years old woman presented with– Increased facial and body hair, acne– Skin greasy– Irregular periods
• Began at the age of 11 years• Always unpreditcable• Miss one or two periods every 3 months since 15 years
– Planning marriage in the next 12 months and hoped to start a family
• Physical Examination– Weighted 85 kg, height 163 cm, body mass index 32kg/cm2
– Hirsutism – Skin: greasy and marked by acne– Fundoscopy, visual fields and eye movement were normal
Imbalanced Sex Steroids
Questions
• What is the differential diagnosis?• Which tests should be performed to confirm
the diagnosis?• How will her symptoms and tests guide
treatment?• Will the couple be infertile?
Secretion of
Progesterone and Estrogen by Ovary
Hypothalamus Pituitary Ovary Axis
29
• Pituitary hormones– FSH: follicle stimulating
hormone – LH: luteinizing hormone
• Ovarian hormones– Estrogen– Progesterone
Time: one cycle (approx 28 d.)
*ovulation
Follicular phase Luteal phase
Intracellular Signalling Pathways Activated by Progesterone and Estrogens
Biological Actions of Estrogens and Progesterone
Target Organ
Estrogen Progesterone
Uterus 1. Endometrial thickening2. Make cervical mucus thinner
and more alkaline
1. Increasing vascularization of the endometrium during the luteal phase
2. Make cervical mucus more viscous
Vagina 1. More comified vaginal epithelium
2. Induce synthesis of pheromones’ in vaginal secretion
1. Induces thick mucus secretions from the vaginal epithelium
2. Causes epithelium to thicken and become infiltrated with leukocytes
Breast 1. Promote growth and proliferation of mammary ducts
2. Enlarge breasts at puberty3. Antagonize milk-producing
effect of prolactin
1. Increases growth of breast lobules and alveoli
2. Induces differentiation of ductal tissue
Biological Actions of Estrogens and Progesterone (conti.)
Target Organ
Estrogen Progesterone
Central Nervous System
1. Inhibits FSH secretion2. Brief exposure of the pituitary to
estrogens decreases its sensitivity to GnRH
3. Prolonged exposure of the pituitary to oestrogens increases its sensitivity to GnRH
4. 4. Increase libido possible by direct effect on hypothalamic neurons
5. induce dendrite proliferation in neurons
1. Inhibits secretion of LH2. Cause a rise in body
temperature and is probably responsible for the slight increase in body temperature at time of ovulation
3. Stimulates ventilation and thereby lowers alveolar pCO2 in both the luteal phase of the monthly cycle and in pregnancy
Biological Actions of Estrogens and Progesterone (conti.)
Target Organ
Estrogen Progesterone
Metabolism 1. Exert protein anabolic effect by increasing androgen output from the adrenals
----
Bone and Cartilage
1. Cause epiphysial closure -
Other 1. Partly responsible for female secondary sex characteristics
2. Renal retention of salt and water3. Inhibit atherogenesis by lowering plasma cholesterol,
inhibiting vascular smooth muscle proliferation, and increasing NO synthesis
4. Can promote thrombosis at high levels
Hormonal Regulation of Ovarian Function
• FSH – Stimulates the growth of the
developing follicle– Promote the conversion from
androgen to oestrogen (through aromatase)
• LH – stimulates steroid production
by the corpus luteum and the developing follicle
– stimulate ovulation (LH surge)
Imbalanced Sex Steroids
Differential diagnosisImbalanced sex steroids
• During puberty of the women– breast development - Requires estrogen– pubic hair development - Requires androgens
• Joanna’s symptoms suggest a disruption of the sex steroid: • excess male hormone
– Polycystic ovary syndrome– Androgen secreting ovarian or adrenal tumours– Genetic condition congenital adrenal hyperplasia
• Reduced female hormones– Disease of pituitary/hypothalamus– Ovarian failure
• Which test should be performed to confirm the diagnosis
Section 3. Hormonal Control of the Menstrual Cycle
39
The Uterine Wall*• Three basic layers– Perimetrium: outer serous membrane– Myometrium: middle muscle– Endometrium: inner mucosal lining
*
40
Endometrium (inner mucosal lining of uterine cavity)
• Simple columnar epithelium containing secretory and ciliated cells
• Lamina propria of connective tissue
2 main layers (Strata)1. Functionalis (functional zone)2. Basalis (basal zone)
(not shed)
(shed if no implantation of baby)
Note:Uterine glandsUterine arteries
Endometrium
• Functional zone – layer closest to the cavity – contains majority of glands – undergoes changes with
monthly cycle• Basal zone – layer just under
myometrium– attaches functional layer to
myometrial tissue– has terminal ends of glands – Remains constant
The Menstrual Cycle : Menstruation
• Loss of egg and uterine tissue via vagina if fertilization does not occur
The Menstrual Cycle : Proliferative Phase
• lasts 10 days• FSH & LH
levels increase • egg matures• follicle
secretes estrogen to prepare uterus
The Menstrual Cycle: Ovulation
• High level of estrogen detected by hypothalamus– increased LH– decreased FSH – follicle bursts – egg
released
Estrogens
The Menstrual Cycle: Luteal Phase
• LH converts follicle to corpus luteum – – secretes estrogen
& progesterone. – Progesterone
prepares uterus – Increased
progesterone keeps LH & FSH low
子宫内膜周期性变化
Amenorrhoea• Primary amenorrhoea : Menarche (初
潮) nerve occurred– Absence of menses by age 16 with normal secondary sexual
characteristics.– Absence of menses by age 14 without secondary sexual development.
• Secondary amenorrhoea– Failure of three or more menstrual periods in
succession in a woman– Cause:
• Pregnancy• Ovarian failure• Pituitary failure• Hypothalamus failure
Hypothalamic Amenorrhea
• Disorder of GnRH secretion, and subsequent failure of FSH and LH secretion
• 1/3 of non-pregnant amenorrhea• Causes– Psychological stress– Anorexia nervosa ( 厌食症) , weight loss– Increased exercise levels– drug-induced amenorrhea – Space-occupying lesion of CNS
Pituitary Amenorrhea
• tumor• Hyperprolactinaemia• Empty sella syndrome ( 空鞍综合征)• Sheehan syndrome ( 席汉氏综合征 )
Ovarian Amenorrhea• Premature ovarian failure
– Ovarian failure occurs before 40 years– Caused by:
• Turner syndrome: absence of one X chromosome• Autoimmune destruction of the ovary
• Polycystic ovarian syndrome– Enlarged ovaries containing numerous cysts– Excessive androgen secretion
Polycystic Ovarian Syndrome
Questions
• What is the differential diagnosis?• Which tests should be performed to confirm
the diagnosis?• How will her symptoms and tests guide
treatment?• Will the couple be infertile?
Section 4 Pregnancy
I. Fertilization and Implantation
58
Fertilization
Hormones Changes during Pregnance
• Human Chorionic Gonadotropin (HCG)• Progesterone and Estrogen• Human Chorionic Somatommotropin (HCS)• Relaxin• Aldosterone • Parathyroid hormone (PTH)
Human Chorionic Gonadotropin (HCG)
• Glycoprotein with a molecular weight of 39,000
• Secreted by the syncytial trophoblast cells• can be measured in the blood 8 to 9 days
after ovulation• Function:
• identical to LH in its effect • maintain the corpus letum
Progesterone and Estrogen• Secreted by corpus luteum
before 5-6 weeks of pregancy and by placenta later
• maintain the endometrium and prevent menstruation
• Estrogen: cause enlargement of uterus, breasts and mother’s female external genitalia
• Progesterone: decrease the contractility of pregnant uterus, inhibit release of FSH and LH from anterior pituitary gland (preventing ovulation)
Progesterone and Estrogen
Human Chorionic Somatommotropin (HCS)
• Also called human placental Lactogen (hPL) • Protein with molecular weight of 38,000• Begins to be secreted by the placenta at the 5th week of
pregnancy• Secretion in direct proportion to the weight of placenta.• Function
– stimulates growth of fetus – regulates metabolism of carbohydrate, fat and protein in both the
fetus and the mother– Stimulate mammary gland
31-64
• Relaxin (松弛素) – From placenta, chorion,
and decidua.– Inhibits uterine
contractions and relaxes ligaments of pelvis
– promote cervical ripening
• Aldosterone – From adrenal gland– Increases sodium and
water retention
• Parathyroid hormone (PTH)– Helps maintain high
calcium levels in the blood
Hormonal Changes during Pregnancy (cont.)
66
Childbirth
Dilation of cervis; head enters true pelvis
Late dilation with head rotation to AP position
Expulsion: head first safest as is largest part
Delivery of the placenta
Hormones Involved in LaborHormones Involved in Labor
• Labor Initiation:Labor Initiation:• Increasing CRH at the end of the Increasing CRH at the end of the
gestationgestation• the resulting secretion of the resulting secretion of
prostaglandinprostaglandin• Decline of progesteroneDecline of progesterone
• Relaxin, promote cervical ripeningRelaxin, promote cervical ripening