151 unit 10

give reason why FSH levels decline during the middle of menstrual cycle

(negative feedback), when estrogen is high FSH lower, highest in day 2 because no estrogen yet... LH surge is stimulated by the rising estrogen.... Know that LH is relatively higher than FSH Need to know estrogen is predominant hormone in proliferative phase and progesterone in progresitive / secretory phase ------------------------- Need to study changes in hormones... need to give reason why FSH levels decline during the middle of menstrual cycle (negative feedback), when estrogen is high FSH lower, highest in day 2 because no estrogen yet... LH surge is stimulated by the rising estrogen.... Know that LH is relatively higher than FSH

Development

After implantation Placenta develops Organ of exchange between maternal and fetal blood Acts as transient, complex endocrine organ that secretes essential pregnancy hormones Human chorionic gonadotropin Maintains corpus luteum until placenta takes over function in last two trimesters Estrogen Essential for maintaining normal pregnancy Progesterone Essential for maintaining normal pregnancy Abnormal uterine contractions = threatened abortion (caused by decreased progesterone level and cervical muscles cannot close due to weak muscles in cervix)

Menstrual Abnormalities

Amenorrhea = absence of menstruation hormone imbalance, extreme weight loss pregnancy Dysmenorrhea = pain associated with menstruation primary dysmenorrhea under age 25 - due to prostaglandins secondary dysmenorrhea uterine tumors, ovarian cysts, endometriosis or intrauterine device PID (pelvic inflammatory disease) Second most common cause is endometriosis

Effects of testosterone

Before birth male genitalia promotes descent of testis At puberty - 2nd sexual characteristics, sexual behavior & libido growth of reproductive system spermatogenesis hair growth, voice, male body, sex drive Non-reproductive functions protein anabolic effect bone growth, closure of epiphyseal plates aggressive behavior

Female Reproductive Functions and Organs

Functions Production of ova (oogenesis) Reception of sperm Transport of sperm and ovum to common site for union (fertilization or conception) Maintenance of the developing fetus until it can survive in outside world (gestation or pregnancy) Formation of placenta (exchange organ between mother and fetus) Giving birth to the baby (parturition) Nourishing infant after birth by milk production (lactation)

Ovarian Cycle

Hormonal interactions During follicular phase, rise in FSH signals ovarian follicle to secrete more estrogen Rise in estrogen feeds back to inhibit FHS secretion which declines as follicular phase proceeds LH rises in follicular phase As it peaks in mid-cycle, it triggers ovulation Estrogen output decreases and mature follicle is converted to a corpus luteum Corpus luteum secretes progesterone and estrogen during luteal phase Progesterone output inhibits release of FSH and LH Low LH - corpus luteum degenerates Progesterone levels decline FSH can start to rise again, initiating new cycle In order for ovulation to happen there must be high levels of estrogen (depends on follicular cells), estrogen is stimulating factor for LH surge which stimulates ovulation, need to study and understand hormones

Hormonal Secretion by the Placenta

Human chorionic gonadotropin (HcG) Rescues corpus luteum from degeneration until the 3rd or 4th month of pregnancy Progesterone / estrogens: Maintains endometrium of uterus during pregnancy Help prepare mammary glands for lactation Prepare mothers body for birth of baby Relaxin: Increases flexibility of pubic symphysis Helps dilate uterine cervix during labor Human chorionic somatomammotropin Helps prepare mammary glands for lactation Enhances growth by enhancing protein synthesis Decreases use and increases fatty acid use for ATP production Corticotropin releasing hormone 1. Establishes the timing of birth 2. increases secretion of cortisol Need to remember names and actions / functions of these hormones... in normal people corticotropin releasing hormone is secreted by hypothalamus, in pregnancy is also secreted by placenta, stimulates babies adrenal gland to secrete DHEA, which converts into testosterone in males and estrogen in females... if estrogen does not overtake progesterone by 7 months of pregnancy

Signs of Ovulation

Increase in basal body temperature Changes in cervical mucus Cervix softens

LH

LH surge ( 1- 2days at mid-cycle) stimulated by peak estrogen secretion terminates the follicular phase initiates the luteal phase Actions of LH maintains corpus luteum CL to secrete both estrogen and progesterone (more abundant) All important for exam

Events in the ovary

Pre-ovulatory (follicular) phase - FSH is dominant - predominant is estrogen Ovulation Post-ovulatory (luteal) phase - LH is dominant, corpus luteum - estrogen and progesterone Primordial follicle there since before baby was born, what is the content in the primary follicle? Primordial cell with meiotic division arrested in prophase 1

Gestation

Pregnancy About 38 weeks from conception Physical changes within mother to meet demands of pregnancy Uterine enlargement Breasts enlarge and develop ability to produce milk Volume of blood increases 30% Weight gain

Hormonal Control of Spermatogenesis

Puberty hypothalamus increases its stimulation of anterior pituitary with releasing hormones anterior pituitary increases secretion LH & FSH LH stimulates Leydig cells to secrete testosterone an enzyme in prostate & seminal vesicles converts testosterone into dihydrotestosterone (DHT-more potent) FSH stimulates spermatogenesis stimulates sertoli cells to secrete androgen-binding protein (keeps hormones levels high) Need to know functions, ABD

Comparison of oogenesis and spermatogenesis

Spermatogenesis Number of gametes Principle: continuous production. Although from puberty to old age sperm cells are constantly being engendered, the production is subject to extreme fluctuations regarding both quantity and quality Meiotic output Four functioning, small (head 4 mm), motile spermatozoids at the end of the meiosis Fetal period No meiotic divisions No germ cell production Oogenesis Number of gametes Principle: Using up the oocytes generated before birth. Continual decrease of the oocytes, beginning with the fetal period. Exhaustion of the supply at menopause. Meiotic output One large, immotile oocyte (diameter 120 mm) and three shriveled polar bodies are left at the end of the meiosis Fetal period Entering into meiosis (arrested in the dictyotene stage) Production of the entire supply of germ cells

differences between primary, secondary follicle and tertiary follicle

The difference between a primordial follicle and a primary follicle is that the primary follicle develops another gelatinous membrane called zona pellucida, which surrounds a mature oocyte. The oocyte is now 80-100 micrometers in diameter and the granulosa cells start to quickly proliferate. As the follicle enlarges, fluid accumulates between the granulosa cells forming small patches. The follicle develops into a secondary follicle when another layer of granulosa cells rests on the outside of the basement membrane. These cells are called thecal cells, which develop into two distinct layers in tertiary follicles. The fluid filled patches enlarge in secondary follicles and form a cavity called antrum.

Endometriosis

condition in which cells from the lining of the uterus (endometrium) appear and flourish outside the uterine cavity, most commonly on the membrane which lines the abdominal cavity, the peritoneum. The uterine cavity is lined with endometrial cells, which are under the influence of female hormones. Endometrial cells in areas outside the uterus are also influenced by hormonal changes and respond in a way that is similar to the cells found inside the uterus. Symptoms of endometriosis are pain and infertility. The pain often is worse with the menstrual cycle and is the most common cause of secondary dysmenorrhea.

Semen

contains fructose, proteins and antibiotics 2 - 6 ml/ejaculation - average 2.75 ml 50-150 million sperm/ml- average 66 million/ml Semen analysis--- bad news if show lack of forward motility, or abnormal shapes (quality) if <20 million sperm/ml (quantity) Need to know this, first investigation done with infertility in couples

spermiogenesis

extensive remodeling or packaging of cellular elements (spermatids) includes their differentiation into four parts: head, acrosome, midpiece, and tail supported by Sertoli cells Maturation of the sperm, remember terminologies for exam

Sertoli cells

form a barrier that prevents the immune system from becoming sensitized to antigens associated with sperm development -tight junctions between sertoli cells forms blood-testes barrier which prevents blood borne substances from passing between the cells to gain entry into seminiferous tubules Because its main function is to nourish the developing sperm cells through the stages of spermatogenesis, the Sertoli cell has also been called the "mother" or "nurse" cell. ----------------------------- The supporting cells (Sertoli) are located within the seminiferous tubules. Their task is the creation of a hemato-testicular barrier and the nourishment of the spermatozoa.

The Menstrual Cycle

monthly rhythmical changes changes in 3 areas ovaries endometrial lining of the uterus Hormones LH and FSH, 2 others estrogen and progesterone

For exam need to study all the changes in fetal period, before pubertty and after puberty, changes in oocytes... product of meiosis 1 and meiosis 2 are different sizes

slide 22

ovarian and uterine phases chart

slide 37

hormone change chart

slide 38

Early Stages of Development from Fertilization to Implantation chart

slide 49

The process of spermatogenesis

spermatogonium - mother cell (46 chromosomes) mitosis 2 x primary spermatocyte (2n) - one stays back and one takes part in spermatogenesis meiosis I secondary spermatocytes (n) 2 in no: 23 chromosomes meiosis II spematids (n) 4 in no: 23 chromosomes spermatozoa ------------------------- From 1 stem cell - 2 daughter cells From 1 daughter cell - 2 identical primary spermatocytes takes about 60 - 75 days

early corpus luteum, mature corpus luteum, corpus albicans

the corpus luteum (Latin for "yellow body") (plural corpora lutea) is a temporary endocrine structure in female mammals that is involved in the production of relatively high levels of progesterone and moderate levels of estradiol and inhibin A. The corpus luteum is essential for establishing and maintaining pregnancy in females. The corpus luteum secretes progesterone, which is a steroid hormone responsible for the decidualization of the endometrium (its development) and maintenance, respectively -------------------------------------------------- When egg is not fertilized[edit] If the egg is not fertilized, the corpus luteum stops secreting progesterone and decays (after approximately 14 days in humans). It then degenerates into a corpus albicans, which is a mass of fibrous scar tissue. The uterine lining sloughs off without progesterone and is expelled through the vagina (in mammals that go through a menstrual cycle). In an estrous cycle, the lining degenerates back to normal size. When egg is fertilized[edit] If the egg is fertilized and implantation occurs, the syncytiotrophoblast (derived from trophoblast) cells of the blastocyst secrete the hormone human chorionic gonadotropin (hCG, or a similar hormone in other species) by day 9 post-fertilization. Human chorionic gonadotropin signals the corpus luteum to continue progesterone secretion, thereby maintaining the thick lining (endometrium) of the uterus and providing an area rich in blood vessels in which the zygote(s) can develop. From this point on, the corpus luteum is called the corpus luteum graviditatis. The introduction of prostaglandins at this point causes the degeneration of the corpus luteum and the abortion of the fetus. However, in placental animals such as humans, the placenta eventually takes over progesterone production and the corpus luteum degrades into a corpus albicans without embryo/fetus loss.

Fertilization

Oviduct is site of fertilization Normally occurs in upper third of oviduct (ampulla) Must occur within 24 hours after ovulation Sperm usually survive about 48 hours but can survive up to 5 days in female reproductive tract Calculate days when there is no pregnancy, calculate which days can guarantee pregnancy ------------------------------ First sperm to reach ovum Fuses with plasma membrane of ovum Triggers chemical change in ovum's surrounding membrane that makes outer layer impermeable to entry of any more sperm Head of fused sperm gradually pulled into ovum's cytoplasm Within hour, sperm and egg nuclei fuse Fertilized ovum now called a zygote

Parturition

Labour, delivery, birth Requires Dilation of cervical canal to accommodate passage of fetus from uterus through vagina and to the outside Contraction of uterine myometrium that are sufficiently strong to expel fetus -------------------- Once contractions begin at labour onset, positive-feedback cycle progressively increases force Pressure of fetus against cervix reflexly increases oxytocin secretion Role of oxytocin Causes stronger contractions Positive-feedback cycle progressively increases until cervical dilation and delivery are complete ----------------------- Stages of labour Cervical dilation - counted from onset of true labor pain until complete dilation of cervix (10cms) Longest stage Average 10-12 hours Lasts from several hours to as long as 24 hours in a first pregnancy Delivery of baby - complete cervical dilation to delivery of baby Begins when cervical dilation is complete Usually lasts 30 to 90 minutes Delivery of placenta - counted from delivery of baby until delivery of complete placenta Second series of uterine contractions separates placenta from placenta Shortest stage - usually completed within 15 to 30 minutes after baby is born Can help by giving supra pubic massage, or give baby to mom to breast feed to stimulate release of oxytocin After delivery, uterus shrinks to pregestational size (involution) There is actually a 4th stage covered in unit 11: recovery stage, usually lasts 1-4 hours, chills, retention of urine

Leydig cells

Leydig cells, also known as interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testicle. They produce testosterone in the presence of luteinizing hormone (LH). Leydig cells are polyhedral in shape, display a large prominent nucleus, an eosinophilic cytoplasm and numerous lipid-filled vesicles

Oogenesis

Oogonia Undifferentiated primordial germ cells in fetal ovaries Divide mitotically to give rise to 6 million to 7 million oogonia by fifth month of gestation During last part of fetal life begin early steps of first meiotic division but do not complete it Now known as primary oocytes Contain diploid number of 46 replicated chromosomes Remain in meiotic arrest for years until they are prepared for ovulation Need to compare spermatogenesis and oogenesis, spermatogenis is in puberty, oogeneisis begins before baby is even born... average puberty is around 9-11 years of age For exam need to study all the changes in fetal period, before pubertty and after puberty, changes in oocytes... product of meiosis 1 and meiosis 2 are different sizes (next slide)

Uterine Cycle

Menstrual phase First day of menstruation is considered start of new cycle Coincides with end of ovarian luteal phase and onset of follicular phase Release of uterine prostaglandin Causes vasoconstriction of endometrial vessels Disrupts blood supply Causes death of endometrium Stimulates mild rhythmic contractions of uterine myometrium Help expel blood and endometrial debris from uterine cavity out through vagina (menstrual flow) When menstruation happens due to lack of hormone support, prostoglandin is released, which helps to vasoconstrict to make less bleeding during menses (day3-day7), supports contraction of uterus, if uterus is weak there will be more bleeding.... Painful menstruation (dysmenorrhea) is due to actions of prostaglandin and endometriosis (abnormal presense of endometrial glands in myometrium, which can also cause infertility)... growth is fibroid which can cause excessive bleeding -------------------------------------------- Proliferative phase Begins concurrent with last portion of ovarian follicular phase Endometrium starts to repair itself and proliferate under influence of estrogen from newly growing follicles Estrogen-dominant proliferative phase lasts from end of menstruation to ovulation Peak estrogen levels trigger LH surge responsible for ovulation ---------------------------------------------------- Secretory or progestational phase Corpus luteum secretes large amounts of progesterone and estrogen Progesterone Converts endometrium to highly vascularized, glycogen-filled tissue Endometrial glands actively secrete glycogen If fertilization and implantation do not occur Corpus luteum degenerates New follicular phase and menstrual phase begin once again Progestational phase under progesterone and LH Progestational phase under progesterone and LH

Events in the uterus

Menstrual phase - end of previous menstrual cycle and beginning of next one, corpus luteum gets degenerated, estrogen and progesterone levels decline, causes shedding of endometrium Proliferative phase Progestational (secretory) phase

Need to study this... need to know morula and blastocyst, HCG is one that maintains corpus luteum

Morula:A morula (Latin, morus: mulberry) is an embryo at an early stage of embryonic development, consisting of cells (called blastomeres) in a solid ball contained within the zona pellucida Blastocyst: its formation begins 5 days after fertilization during the germinal stage of development. It possesses an inner cell mass (ICM) which subsequently forms the embryo. The outer layer of cells of the blastocyst are called the trophoblast. This layer surrounds the inner cell mass and a fluid-filled cavity known as the blastocoel. The trophoblast gives rise to the placenta.

Initiation and Progression of Parturition chart

Need to study this (everything except 6 blocks to the left), estrogen is important after 7 months of pregancy so that uterine contractions can happen... presence of estrogen will make muscles of uterus more sensitive to oxytocin... factors combine to produce labor... 4 or 5 questions from this flow chart slide 55