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Reproductive Physiology
reproductive_health2 (Pregnancy and Parturition…
Reproductive Physiology
Control of Gonadal and Gamete Development
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Modification of Ganodotropin Release
:star: secretory pattern of gonadotropins is pulsatile by GnRH from the hypothalamus
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continual occupancy of GnRH receptors on gonadotrophs interrupts the intracellular signal for synthesis and release of gonadotropins
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dose must diminished as ovulations or downregulations will occur.
- hypothalamus :heavy_plus_sign: adenohypophysis :arrow_forward: responding increase estrogen secretion by increased secrection of gonadotropins called termed positive feedback
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secretion of gonadotropins is modified by ovarian steriod hormones = estrogen :heavy_plus_sign: progesterone
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hormone suppressive for gonadotropins secretion
:star: estrogens cause negative feedback inhibition :arrow_forward: sensitivity and rapid onset, caused largely removal of estrogens
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progesterone affects gonadotropins in the hypothalamus, so estrogens also affect secrection on both pituitary gland and hypothalamus
- secretion of gonadotropins can be modified by peptide and protien hormones produced by hypothalamus and the ovary.
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beta-endorphin produced from hypothalamic inhibit LH secrection and another protien produced by the granulosa cell develop follicle during final stage of follicle developement.
- prolactin :arrow_forward: third adenohypophysis-produced hormone important in the reproductive process that effect mammary gland and lactation in mammals
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secrection in pulsatile pattern and more emphasis on inhibition than stimulation of secretion.
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factors inhibition :arrow_forward: cholamine dopamine,GABA, GAP
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Reproductive Cycle
2 types of reproductive cycles:
:pencil2:estrous
:pencil2:menstrual
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ovarian cycle representing two successive ovulations
:star:in domestic animals and primates
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have limited periods of estrus or sexual receptivity term estrous cycle while primates are sexually receptive term menstrual cycle
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both cycle in many species begins shortly after end of the luteal phase
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domestic animal proestrus begin within 48 hours after end luteal phasewhile in primates menstruation begins 24 hours end of the luteal phase
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ovulation in domestic is easier to detect compare to primates :arrow_forward:usually tightly coupled to the preovulatory release of gonadotropins and ovulation
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estrous cycle divided into 4 stages
:explode:proestrus
:explode:estrus
:explode:metestrus
:explode:diestrus
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in domestic common terminologies used is behavioral and gonadal activity :arrow_forward:describe behaviora manner in estrus
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dog and cat ovarian status determining by measuring serum progesterone levels
Puberty and Reproductive Senescene
:star:female begin reproductive cycles
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undergo puberty :arrow_forward:define onset of reproductive life
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mechanisms control of puberty involves increase in synthesis and release of gonadotropin-releasing hormone from hypothalamus
:star: before puberty
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GnRH and gonadotropin secretion are kept in hypothalamus is negative-feedback inhibition by estrogens
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different animal have different changes photoperiod allowing to enter pubert depends on physiological maturity of the individual
:star:primates ovarian activity
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menopause :arrow_forward:depletion of oocytes which occurred throughout the reproductive life of the individual
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represent failure develop primordial state or absence of gonadotropins receptors
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often involves cyclical irregularity caused by failure of follicle development and ovulation
Sexual Behavior
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depends on exposure of hypothalamus to testosterone during neonatal period
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presence of testosterone cause masculinization while absence become ferminized
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medial preoptic area is modified structurally by exposure to testosterone
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effect of hormone on sexual behavior
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:fire:mangnitude of change in hormone concentration
:fire:synergism between hormone
:fire:sequence of exposure to hormone
External factors controlling reproductive cycles
:star:Photoperiod
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control the occurrence of reproductive cycles
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result have an annual period which they continuous ovarian cycle
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positive response to change occurrence of summer or winter solstice while negative response to long duration for an effect
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main translator of photoperiod is the pineal gland which produce melatonin response to darkness
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suppressive effects of photoperiod can be overcome by exposure to artificial lighting regiments
Lactation
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suppressive effect on ovarian activity
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involves the suckling stimulation of prolactin synthesis
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inhibiting factors for prolactin systhesis including dopamine and GnRH
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sensory input from suckling sysnthesis of gonadotropins and reduced output ovarian activity
Pheromones
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chemical compounds that allow communication among animals through olfactory system
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sexual behavior affected called sex pheromones
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arise tissue for animals are sebaceous glands
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important for the attraction of the male to female sexual receptivity
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have a musk type of odor
Pregnancy and Parturition
Development of an embryo
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sperm ejaculated into vagina directly into cervix and uterus
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movement sperm into cervix is aided by estrogen-induced in cervical mucus that facilitate movement of sperm
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environment of female genital is not suitable for sperm survival
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have special reservoir during transport at the uterotubule junction and within the ampulla
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ampulla release sperm for fertilization after arrival of oocytes within the oviduct
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sperm undergo capacitation removal glycoprotien from sperm surface
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allow sperm to undergo acrosome reaction contact with oocytes that release hydrolytic enzymes to penetrate granulosa and zona pellucida oocye plama membrane
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fertilization occured
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form morula to blastocyst state before moving to utrerus wall
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nutrient essential for the development of embryo during preimplantation stage
Life Span of the Corpus Luteum
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in domestic animal embryo produce modify uterine production of PGF2alpha and estrogen synthesis
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trophoblast produced before day 14 for the establishment of of pregnancy
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movement of embryo important for pregnancy recognition
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suppression or modification of the secretion PGF2alpha
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critical extension of life span of the CL in large domestic species
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one hormone synergizes with progesterone support pregnancy is relaxin a placenta
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implantation called interstitial which penetrates the endometrium after ferilization
:explode:eccentric for dog/cat
:explode: caruncles for ruminant
:explode:villus for horse and pig
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implantation begin then another week embryonic nutrition is obtained through the implantation
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cervix form a barrier to contamination of the uterine lumen later on sealed
Placenta act as endocrine organ
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providing nutrient and oxygen for embryonic metabolism also production of progesterone and estrogen
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maintain pregnancy in domestic animal
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protein hormones produced during pregnancy from placenta is relaxin
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support of pregnancy through a synergistic action with progesterone
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placental lactogen is another protien hormone
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increase CG secretion during pregnancy
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hormone appear somatotropic and lactogenic effects and prolactin-like properties
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for domestic animal placental lactogen important for mammary gland alveolar development for lactation
Partutrition
during pregnancy
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progressively enlarge and stretches growing fetus
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progesterone maintaining myometrium promoting contracted cervix
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during gestation
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estrogen influence the muscle by stimulating the production of contractile protein and formation of gap junction
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facilitates the contratile potential of the uterus thus communication among smooth muscle cells
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stage parturition begin cervix relaxes and open to allow the fetus to be delivered
:star:PGF2alpha
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synthesis through increased arachidonic acid
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estrogen propposed to influence making enzyme phospholipase
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membrane-bound lysosomal enzyme that initiates hydrolysis and release of arachidonic acid
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results increasing estrogen/progesterone with progesterone stabilizing then estrogen destabilizing lysosomal membrane
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immediate release of PGF2alpha on myometrium to release intracellular calcium ion which binds actin and myosin to contractile process :arrow_double_down:
effect on cervix allow to relax and dilate permitting the passage of the fetus.
:star:Oxytocin
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important to the delivery process where estrogen induces oxytocin receptor formation in myometrium :arrow_double_down:
occur through Ferguson reflex involves passage of impulses through sensory nerves in the spinal cord in hypothalamus
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transport oxytocin from neurohypophysis by the vascular system also synergitic with PGF2alpha promoting contraction of the uterus
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relaxin another hormone for parturition
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responsible separation of the pubic symphysis through relaxion of the ligament
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caused ligament and muscle surrounding pelvic canal to relax allow fetus to expand
Stage of Parturition
:star: 1 stage
presentation of the fetus at the internal os of the cervix
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increased myometrium activity caused by PGF2alpha release
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cervix open and fetus passes into pelvic canal and myometrium contract for delivery fetus
:star: 2 stage
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abdominal press by closure of the epiglottis and contraction abdominal muscle force in delivery process
:star:3 stage
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involves the delivery of the fetal membrane
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in litter-bearing placental membrane delivered immediately after appearance of each fetus while single-bearing placental delivered within few hours
Mammary Gland
Anatomical mammary gland
mammary gland derived from embryonic ectoderm
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continuity of the ridge form and broken into mammary buds
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parenchyma or milk-secreting cells :arrow_forward:develop through proliferation of epithelial cells arise from the primary mammary cord
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form hollow ,circular structures called alveoli for milk-secreting of the mammals
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enlarged area epithelium form nipple which is the external connection to the milk-secreting systems while in male mammary cord not develop into glandular tissue
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duct system connect alveoli with the nipple enabling milk to pass
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opening duct and positions of mammary glands varies in animals.
:star:Udder
important adaptations in dairy that allow carry large amounts of milk
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formed by median suspensory ligament composed of elastic connective tissue that originate from abdominal tunic while lateral originates from subpubic ligament enters the gland become interstitial connective tissue framework of the udder
:star: Control of mammogenesis
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development of mammary gland under both genetic and endocrine control
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initial development is the mammary bud under control of embryonic mesenchyme
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mammary mesenchyme transplanted known fetal mammary development actively secreting exogenous hormone
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mammary gland start with puberty result production of estrogen and progesterone :arrow_forward: estrogen responsible for proliferation of the duct system and development of alveoli from the terminal ducts which require progesterone and prolactin
:star: Colostrum
formed before parturition
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formation represent secretory process which lactogenesis abence in milk removal
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lactation cannot fully blossom until pregnancy because inhibitory effects of progesterone and estrogen on milk removed before delivery.
:star:Important ingestion of colostrum
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important for the well-being of the neonate as passive protection against infections agents (IgA) :arrow_forward:produced in the mammary gland by plasma cells
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access to the milk system through migration of the plasma cell with high concentrated thus neonate can receive passive immunity against pathogens
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allow young receive immediate protection from environmental organisms
:star:Limited time ingestion of colostrum
neonates usually have 24-36 hours which immunoglobulins can be absorbed through the gut
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important to ensure the presence of immunoglobulins in the newborn
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antimicrobial factor in milk important for protection against development of pathogenic enteric bacterial flora
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colostrum rich of nutrient vitamin A and immunoglobulins :arrow_forward:transfer Vit.A through placenta in domestic animal
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caseins and albumins also present with high concentration
Lactogenesis
:fire: Prolactin play important role in secretion of milk or lactogenesis
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release manipulation of the teat through suckling or milking process
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stimuli hypothalamus and synthesis or release of dopamine inhibitor of prolactin secretion blocked by neurons in the paraventricular nucleus stimulated to produce and release vasoactive intestinal peptide
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alveolar cells synthesis fat,protein and carbohydrates and extrude into lumen of the alveolus
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fat droplets accumulate basal cytoplasm then move to the apex where protrudes into alveolar lumen
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milk protein synthesized on the endoplasmic recticulum the casien pass through to the golgi apparatus
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phosphorylated and formed into micelles golgi vesicles and lactose also synthesized and release in conjuction with milk protein
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fuse with cell membrane and release of protein and carbohydrates by exocytosis
:star:Milk removal
milk must removed from the mammary gland by suckling and milking
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if not removed within 16 hours, milk begin to suppressed
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to facilitate the process, myoepithelial cells surround the alveoli and duct
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responsive to oxytocin synthesis and release from the posterior pituitary by neuroendocrine reflex
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involving stimulation of the udder by suckling or manual
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sensory stimuli carried through the spinal cord into the hypothalamus
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paraventricular and supraoptic nuclei stimulated to synthesize oxytocin release from nerve
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increased pressure within the mammary gland stimulation milk forced out of the alveoli and ducts by contraction of myoepithelia cells
Composition of Milk
most energy source composed lipids including monoglycerides,diglycerides,triglycerides ,free fatty acids main component of milk fat
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amount of fat produced varies among species
:star:lactose
main carbohydrates of most mammals composed of glucose and galactose
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formed under lactose synthetase an enzyme composed alpha latalbumin and galactosyl transferase
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prolactin also stimulatory for formation of lactose synthetase
:star:Caseins
main protein produced by alveolar cells
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removed as curd from milk through curdling or coagulation with other milk protein
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remaining in the fluid part of the milk (whey)
Lactation cycle
time required changeover colostrum to normal milk secretion varies with each species
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milk production tends to increase for the first 3-4 weeks of lactation and slowly end of lactation
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pressure of milk within the alveolar gradually inhibits the secretion of milk result regression of the alveolar cells and small ducts
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process called involution required at least 6 week period interval from drying off the next lactational period
:star: Induction of lactation
in dairy cattle with high-lactation but poor reproductive performance :arrow_forward: combined treatment of estrogen and progesterone induced alveolar development sufficiently in milk production.
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growth hormone important in lactational process used to enhancement of lactation when administered
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ability synthesize GH is use for increasing the amount of milk produced
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GH act on postabsorptive use in nutrient so that protein, fat, carbohydrates metabolism changed and nutrient directed toward milk synthesis
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increase gross efficiency of lactation
:star: Disease
:explode: mastitis :arrow_forward: inflammation of the teat canal from repeated stretching with milking process
:explode: neoplasia :arrow_forward: mammary tumors, exposure of hormone estrogen and progesterone increase
:explode:red blood cell agglutinating antibodies to fetus through the milk :arrow_forward:pass to maternal system and elicit antibody formation against the fetal RBC, tend to concentrated in the colostrum along with the immunoglubolins
:explode:hypocalcemia :arrow_forward: increase calcium from the blood into milk drain from the bloody by mobilization of calcium, lose ability to maintain normal muscle activity
Male Reproductive System
Functional anatomy
made up of number of organs to produce spermatozoa and transport to the female reproductive tract
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involves hypothalamus and pituitary gland and genital system
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consist external and internal part
:explode:external part: testis,penis and scrotum
:explode:internal part: epididymis,vas deference,seminal vesicles,prostate gland, bulbourethral gland
:star:Emission/Expulsion
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Emission :arrow_forward: release of spermatozoa and accessory gland fluid into the pelvic urethra by sympathetically thoracolumbar reflex contraction smooth muscle
Expulsion :arrow_forward:ejaculation forceful of semen from the urethra by parasympatically sarcral reflex that rhythmic contractions of bulbospongiosus
Spermatogenesis
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haploid spermatogonium undergo mitosis and produce one cell remain spermatogonium and other cell become primary spermatocycte
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the primary spermatocycte undergo meiosis 1 and produce secondary spermatocycte
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secondary spermatocycte also again undergo meiosis 2 to speperating chromosome pairs into 4 cell with diploid called spermatids
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spermatids differentiate and form true sperm and store at the lumen of the epididymsis for maturation
Regulation feedback mechanism involving hypothalamus and anterior pituitary also testis
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hypothalamus synthesis and secrete GnRH in a pulsatile manner
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send to the ganodotropins cell in the anterior pituitary
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release 2 hormone :arrow_forward: LH/FSH
:explode: LH :arrow_forward: bind to membrane receptor an leydig cell stimulus and convert cholesterol into testosterone thus synthesized androgen diffuse into blood/lymph then facilitates transport of androgen from testis to epididmysis for maturation of spermatozoa
:explode:FSH :arrow_forward: target receptor of sertoli cell within seminiferous tubules then FSH/testosterone stimulate sertoli cell by secretion ABP that involved in the transfer nutrient to germ cell then inhibin produced by sertoli cell to response FSH and stimulating steroidogenesis in leydig cell
Puberty
hypothalamus initiation of puberty
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suppresion of GnRH synthesis and pulsatile secretion
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stimulation of pituatary by GnRH and gonand by LH/FSH
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initiation/progression of puberty
:star:Factor affect puberty
:fire: age
:fire:breed
:fire:energy intake
:star: Anabolic steriod
:pencil2:synthetic/human-made of the male sex hormone testosterone
:pencil2:increase performance,mental attitude,stamina and physical strenght
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influence of androgen max/minimize androgenic side effect
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lead to incomplete development of hypothalamic pituitary-gonadal axis
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effect smaller testicles and low sperm production
Corpus Luteum
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CL secretion of progesterone which prepares the uterus to initiation and maintenance of pregnancy
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from wall of follicle which collapsed and folded after ovulation
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rupture of the follicle break down the tissue surround the granulosa caused hemorrhage into cavity from vessels in the theca.
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the fold inward into the cavity contain granulosa and theca that support cell growth and differentiation
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granulosa cells undergo changes from estrogen to progesterone secretion and luteinization begins of preovulatory and accelerates with ovulation
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LH important for luteotropin with CL maintained in non-pregnant and pregnant by slow pulsatile pattern of LH release ( one pu;se per 2-3 hours)
:star: Regression of the CL in non-pregnant large animals controlled by uterine secretion of PGF2alpha
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uterus is responsible for control of the duration of the life span of CL
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in large animals, regression of CL initiated by uterine synthesis and release of PGF2alpha about 14days
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mode occur by local countercurrent transfer or general systemic transfer
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across the blood vascular system from higher concentration to low concentration involve general circulatory system.
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PGF2alpha rapidly metabolized systemically by one passage through the lungs
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pattern of synthesis and release PGF2alpha is pulsatile about 6 hour intervals to be affected
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minimum 4-5 pulses within 24 hours required to cause complete luteolysis
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recycling not present in non-pregnant dog and cat as regression of CL lutueal phase about 35-70 days
:star: changes in luteal life span in PGF2apha synthesis by the uterus
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the presence of embryo blockage of PGF2alpha synthesis and continuance in luteal activity.
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absence of uterine horn affect luteal phase lengthened which control the CL
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in non-pregnant , inflammatory response of the endometrium caused by bacterial sysnthesis and release of PGF2alpha
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premature luteolytic and shorting of the estrous cycle :arrow_forward: pathognomonic for uterine infection
Ovarian cycle
:pencil2: interval between successive ovulations
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composed 2 phase :arrow_forward: follicular/ luteal phase
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primates complete seperation of follicular and luteal phases with no follicle growth until luteolytic complete but large animal follicle growth does not occur during luteal phase of the cycle.
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follicle growth and luteolysis is shorter in dometic animals than primates
:star: animals require copulation for ovulation are known induced ovulators (cat,rabbits)
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replaces estrogen as stimulus that induces ovulatory release of gonadotropins
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have follicle growth pattern which cohorts of follicle develop :arrow_forward: maintained then regress
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