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206 Cards in this Set
- Front
- Back
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Serosa
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Serous Membrane
Covers surface of reproductive tract Simple squamous |
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Muscularis
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Smooth muscle layer
Circular and longitudinal layers |
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Submucosa
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Varies in thickness depending on region
Blood vessels, nerves, lymphatics Supports mucosa |
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Reproductive Tract
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Surrounded by peritoneum that is continuous with the broad ligament
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Broad Ligament
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Part of Peritoneum
Supports and Suspends Ovaries, Oviduct, Uterus, Cervix, Anterior Vagina Houses vascular supply, lymphatics, drainage, nerves Failure of broad ligament leads to vaginal/uterine prolapse |
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Mesovarium
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Anterior/cranial portion of broad ligament
Supports ovary Houses blood and lymphatic vessels Forms hilus (holds blood vessels) |
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Mesosalphinx
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Supports oviduct
Helps orient infundibulum so that ova may be directed to the oviduct |
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Mesometrium
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Supports uterine horns and body of uterus to dorsal body wall
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Ovaries
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Primary sex organs
Produce gametes/oocytes Produce sex hormones (estrogen/progesterone) |
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Corpus Luteum
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Part of ovaries
Oxytocin, relaxin, inhibin, activin |
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Germinal Epithelium
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Structure in ovaries
Simple cuboidal Surrounds tunica albuginea Does not produce germinal cells |
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Tunica Albugenia
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Connective tissue capsule
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Ovarian Cortex
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Deep to tunica albuginea
Houses growing oocytes (except in horses), functional corpus luteum, corpus albicantia |
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Corpus Albicantia
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Degenerating corpus luteum
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Ovarian Medulla
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Houses blood vessels, nerves, lymphatics
Dense connective tissue |
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Ovarian Follicles
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Located within cortex of ovary
Oocyte surrounded by follicle cells |
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Oocyte
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Primary: Oogonia (diploid)
Secondary: Haploid |
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Primordial Ovarian Follicle
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Most immature type
Oocyte surrounded by flattened cells |
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Primary Ovarian Follicle
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Oocyte surrounded by single layer of cuboidal cells
Either develops into secondary follicle or degenerates |
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Secondary Ovarian Follicle
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Oocyte surrounded by many layers of follicular cells
Oocyte surrounded by zona pellucida |
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Zona Pellucida
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Layer of glycoproteins
Surrounded by plasma membrane |
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Antral/Tertiary Ovarian Follicle
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Oocyte surrounded by: zona pellucida, corona radiata, enlarged antrum, many layers of follicle cells
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Corpus Hemorrhagicum
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Forms immediately after ovulation
Result of protrusion of tissue and rupture of blood vessels |
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Corpus Luteum
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Produced when follicle ruptures
Secretes progesterone (stimulates growth of uterine endometrium) |
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Corpus Albicans
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White connective tissue scar
Forms when corpus luteum regresses |
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Infundibulum
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Part of oviduct
Lateral, funnel-like opening of the tube Encircled by fimbriae (finger-like projections) Captures ovulated oocyte |
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Ampulla
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Part of oviduct
Medial to infundibulum Large diameter compared to isthmus |
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Isthmus
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Part of oviduct
Medial to ampulla Smaller diameter |
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Muscularis
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Part of oviduct
Transports: ovulated oocyte and spermatozoa to site of fertilization |
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Uterus Functions
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Sperm transport
Luteolysis and control of cyclicity Environment for pre-attachment embryo Maternal contribution to placenta Expulsion of fetus and fetal placenta |
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Duplex Uterus
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2 cervical canals
Separate each uterine horn into distinct compartments 2 uterine horns, 2 cervixes, single vagina opening 2 Types: one with one vaginal canal, another with two |
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Bicornate Uterus
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2 uterine horns
Small uterine body single cervical canal Cows and Mares: poorly-developed uterine horns Ewe, cow, queen, bitch: highly-developed uterine horns |
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Simplex Uterus
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Single uterine body
No uterine horns Primates |
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Perimetrium
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Outer serosal layer of Uterus
Part of peritoneum Continuous with serosal layer of mesosalphinx Thin, transparent |
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Myometrium
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Muscularis of uterus
Longitudinal outer layer, circular inner layer |
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Endometrium
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Mucosa secretes materials into lumen of uterus, enhances embryo development and sperm viability, contains uterine glands which penetrate submucosa
Submucosa is mostly connective tissue, houses uterine glands |
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Endometrium (2)
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Produces prostaglandin f2
In absence of embryo, causes luteolysis Ruminants have caruncles (small protuberance, highly vascular, give rise to maternal portion of placenta) Sow and Mare: many endometrial folds, provide uterine surface for development of placenta |
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Cervix
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Fibrous, collagenous, thick-walled
Small amount of muscle with constricted lumen Contains single/multiple folds, or rings |
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Cervix types by species
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Ewe/cow (prominent ridges, close together)
Bitch/queen (smooth) Sow (interlocking digital pads that holds boar's cockscrew penis during copulation) Mare (loose folds that protrude into uterus) |
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Cervix Function
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Site of semen deposition (sperm reservoir)
Produces mucus Seals during pregnancy to serve as a barrier to uterus Birth canal |
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Vagina Functions
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Copulatory organ
Expulsion of urine during micturation Birth canal |
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Vagina
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Highly acidic environment (prevents bacterial infection, unfavorable to spermatoza)
Puts pressure on penis to stimulate ejaculation Cranial vagina formed from paramesonephric ducts Caudal vagina formed from invagination of urogenital sinus |
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Vulva
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External
Labia majora, minora minimizes foreign entry of material |
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Commissures
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External
Sites of union of labia (dorsal/ventral) |
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Perineum
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External
Area surrounding vulva and anus Covers pelvic outlet Can be torn during a difficult parturition |
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Clitoris
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External
Erectile tissue Highly innervated Homologous to glans penis Located in ventral commissure Serves to control copulation in some species |
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Vestibule
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External
Common duct for urine and fetus during parturition Also functions to stimulate penis during copulation |
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Spermatic Cord
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Extends from inguinal ring to its attachment on the dorsal pole of the testis
Provides vasculature, lymphatic and neural connection to the body Thermoregulation of testes House the cremaster muscle |
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Spermatic Cord Structures
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Vas deferens
Testicular artery (branch of the abdominal artery) Pampiniform plexus (network of veins surrounding testicular artery) Cremaster muscle Autonomic nerves Lymphatics |
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Pulse Pressure Elimination
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Testicular artery serves as a pulse pressure eliminator
Pulse pressure: difference between systolic pressure and diastolic pressure |
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Cremaster muscle
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Supports testis
Aids in temp control of testes (contraction/relaxation; causes pumping action of pampiniform plexus) |
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Intra-abdominal testes
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Birds, elephants, sloths, armadillos, some marine animals (whales, dolphins)
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Scrotum
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Protective, two-lobed sac that functions in thermoregulation
Skin, tunica dartos, scrotal fascia, parietal tunica vaginalis |
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Scrotum - Skin
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Sweat glands, sensory nerves, little/no fat
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Scrotum - Tunica Dartos
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Dartos muscle (smooth)
Thermoregulation (cold = contraction to decrease surface area; hot = relaxation to increase surface area) |
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Testes
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Primary reproductive organ in males
Produces: spermatozoa, hormones, proteins, milieu (fluid) |
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Testicular Capsule
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Outer covering of testis
Two layers: visceral vaginal tunic, tunica albuginea Dynamic Undergoes changes in direct response to hormones and neurotransmitters |
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Tunica Albugenia (testes)
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Connective tissue and smooth muscle
Contractions induced by acetylcholine and norepinephrine |
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Testicular Parenchyma
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Seminiferous tubules
Interstitial cells (Laydig cells) Capillaries Lymphatic vessels Connective tissue |
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Mediastinum
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Central connective tissue core of testis
Houses rete tubules |
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Seminiferous Tubules
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Convoluted tubes
Ends join with rete tubules Tubulus contortus, rectus Basal, adluminal compartments |
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Sertoli Cells
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Located within Adluminal Compartment
Only somatic cells within the seminiferous epithelium Anchored to basement membrane Surround germ cells Contain receptors for FSH, testosterone Produce: androgen binding protein, sulfated glycoproteins 1/2, transferrin, inhibin Join each other via tight junctions Form permeability barrier |
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Basal Compartment of Sertoli Cells
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Contains spermatogonia, early primary spermatocytes
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Adluminal Compartment of Sertoli Cells
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Primary spermatocytes, secondary spermatocytes, spermatids
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Sperm Transport
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Tubulus contortus
Tubulus rectus Rete tubules Excurrent duct system (efferent ducts, epididymis, ductus deferens, urethra) |
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Epididymis
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Single highly convoluted tube
Three regions: caput, corpus, cauda Sperm maturation Sperm reservoir Sperm transit time altered in cauda during sexual exitation (smooth muscle contracts to transport spermatozoa into ductus deferens) |
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Spermatozoa in Cauda Epididymides
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Eligible for ejaculation
Sexual preparation (increases spermatozoa in ejaculate) Can be depleted after multiple ejaculations Non-cellular fluid vehicle for delivery of spermatozoa to female Not required for fertilization |
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Seminal Plasma
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Epididymis
Accessory sex glands (ampulla, vesicular glands, prostate gland, bulbourethral glands) |
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Accessory Sex Glands
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Production of seminal plasma
Located along pelvic region of urethra Secretions: solution of buffers, nutrients, substances needed to assure sperm motility and fertility |
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Ampulla
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Enlarged end of vas deferens (increase in mucosa)
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Vesicular Glands
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Seminal vesicles
Lobular Glands Secretions: fructose, sorbitol |
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Prostate gland
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Single gland
Located at the junction of the bladder and pelvic urethra Two structural forms: corpus/disseminate prostate |
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Bulbourethral Glands
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Pair of organs
Located on either side of the pelvic urethra near ischial arch |
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Penis
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Copulatory Organ
Compromised of: base, shaft, glands penis Sigmoid flexure (s-shaped bend in penis in bulls, boars, rams) Retractor penis muscle (pair of smooth muscles; relaxation = penis extention; contraction = penis drawn back) |
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Erectile Tissue
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Corpus spongiosum (tissue surounding urethra)
Corpus cavernosum (tissue on dorsal aspect of penis) |
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Pituitary Gland: Anterior Lobe
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Contains specialized epithelial cells that produce glycoproteins
Gonadotrophins (follicle-stimulating hormone, leutenizing hormone) Originates from stomodeal ectoderm (tissue in roof of embryo's mouth) - Ranthke's pouch |
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Pituitary Gland: Posterior Lobe
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Contains axons and telodendria of neurons whose cell bodies are in the hypothalamus
Oxytocin Originates from neural tissue from a diverticulum from the floor of the brain (infundibulum) |
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Pituitary Gland: Development
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Stalk on Ranthke's pouch regresses and separates from the stomodeal ectoderm
Infundibulum continues to grow to form posterior lobe Ranthke's pouch associates with posterior lobe Both lobes become surrounded by sella turcica of sphenoid bone |
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Sex determination
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Initiated at fertilization
Spermatozoa delivers X or Y chromosome to oocyte |
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Early Embryo
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Yolk Sac: extraembryonic structure that develops from primitive endoderm, regresses in size as conceptus develops
Primordial germ cells develop in yolk sac, migrate into midgut, reside in genital ridge Genital ridge: gonadal ridge; undifferentiated gonad located on the dorsal body wall, eventually forms gonads Primordial germ cells reach genital ridge, stimulate proliferation of connective tissue, causing primitive sex cords to form |
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Pronephros
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Embryonic Renal System
Non-functional remant of primitive kidney found in lower animals Regresses and is evetually replaced by mesonephros |
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Mesonephros
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Embryonic Renal System
Simple version of adult kidney Produces urine that is drained by mesonephric ducts |
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Mesonephric ducts
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Embryonic Renal System
Eolffian ducts Bilateral pair of ducts Empty into urogenital sinus |
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Paramesonephric ducts
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Embryonic Renal System
Mullerian ducts Pair of ducts on either side of the mesonephric ducts Develops at the same time as mesonephros |
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Sexually Indifferent Stage
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Embryo is uncommitted when it comes to sex
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Metanephros
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Embryonic Renal System
Final renal form Forms as a small bud from caudal end of mesonephric duct Increases in size as the mesonephros loses its function and regresses |
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Embryonic Renal System Formation
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Gonad, metanephros continues to enlarge
Metanephric duct eventually becomes ureter Mesonephros almost completely regresses Mesonephric tubules = efferent ducts Mesonephric duct = epididymis and ductus deferens Metanephros becomes fully functional Gonad becomes larger |
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Development of Testes
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5-15 Mesonephric tubules penetrate into primitive gonad
Undifferentiated sex cords begin to align with rete tubules Mesonephric tubules connect with primitive sex cords via rete testes Undiffeentiated sex cords develop into epithelial cords, which eventually form seminiferous tubules Mesonephric duct eventually forms epididymis and ductus deferens |
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Peritoneum of Testis
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Visceral vaginal tunic, parietal vaginal tunic
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Descent of Testes
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Cells of peritoneum infiltrate and fuse with gubernaculum
Gubernaculum penetrates inguinal ring Rapid growth of gubernaculum moves testes into inguinal canal When testes are in inguinal region, gubernaculum regresses and testes move through inguinal opening Gubernaculum continues to regress Testes move deeper into scrotum |
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Cryptorchidism
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Testes fail to enter scrotum
Special thermal needs of testes not met Endocrine function of testes is not affected Bilateral version results in sterility Secondary sex characteristics are normal |
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Inguinal herniation
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Portions of intestine pass into vaginal cavity and enter scrotum
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Absence of TDF
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Cells of sex cords differentiate into primitive follicular cells
Most of genital ridge becomes ovary |
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Development of Ovary
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Primordial Germ cells do not penetrate genital ridge, form along outer surface of future ovary to form cortex
Rete tubule does not form (gametes do not have to pass through tube) Paramesonephric duct grows, sex cord regresses, primitive germ cells do not regress |
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Development of Ovary and Oviduct
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Cranial end of paramesonephric duct remains open, caudal end associates with dorsal wall of urogenital sinus
Primitive germ cells begin to develop Complete regression of mesonephric tubules and ducts |
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Formation of ducts
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Fusion of paramesonephric ducts
Small bud from urogenital sinus fuses with paamesonephric ducts Formation of uterine horns, uterine body, cervix, cranial vagina Formation of caudal vagina and vestibule from urogenital sinus |
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Formation of Vagina
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Oviducts, uterus, cervix and cranial vagina originate from paramesonephric ducts (mesoderm)
Caudal vagina and vestibule originate from the invagination of the urogenital sinus (ectoderm) Genital fold = future broad ligament |
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Freemartinism
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Form of intersexuality
Occurs mostly in cattle bearing heterosexual twins May also occur in pigs, goats, sheep, horses In cattle: gonads of male develop earlier than those of female Gonads produce male hormones earlier in development, male hormones reach the female embryo and influence the development of male sex in female embryo Testes produce anti-mullerian hormone Paramesonephric ducts in female do not develop completely Ovaries do not grow Sterile inter-sex with female phenotype with sterile male gonads and bullish behavior |
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Regulation of Reproduction
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Interaction between nervous and endocrine systems to initiate, coordinate, and regulate all reproductive functions
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Hypothalamus
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Neural control center for reproductive hormones
Hypothalamic nuclei |
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Hypthalamic nuclei that Control Reproduction
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Surge center (releases GnRH)
Tonic center (releases GnRH) Paraventricular nucleus (PVN; releases oxytocin) |
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Hypothalamo-hypophyseal portal system
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Axons from cell bodies of the surge center and tonic center
Extend into pituitary stalk region Nerve endings terminate at the hypothalamo-hypophyseal portal system (capillary system) |
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Posterior lobe of pituitary gland
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Does not have a portal system
Neurohormones are deposited directly into capillaries in the posterior lobe of pituitary Cell bodies in PVN synthesize oxytocin Oxytocin is transported along the axons Stimulation of neuron induces release of oxytocin into blood |
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Feedback Mechanisms
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Positive - stimulate GnRH neurons
Negative - Suppress GnRH neurons |
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Hypothalamic Hormones
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Produced by neurons located in hypothalamus
Function: stimulate release of other hormones Gonadotropin-Releasing Hormone (GnRH) = neuropeptide, decapeptide |
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Pituitary Hormones
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Released into the blood from the anterior and posterior lobes of pituitary
Anterior Lobe: follicle-stimulating hormone (FSH), lutenizing hormone (LH), prolactin Posterior lobe: oxytocin |
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Gonadal hormones
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Originate from gonads
Function: affect function of hypothalamus, anterior lobe of the pituitary and reproductive tissues Initiate development of secondary sex characteristics (maleness, femaleness) |
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Other hormone sources
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Hormones produced by uterus: Prostaglandin F2(alpha)
Hormones produced by placenta: Progesterone, estrogen, equine/human chorionic gonadotropin (eCG/hCG), |
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Neurohormones
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Synthesized by neurons
Released directly into bloodstream Can cause a response in a tissue elsewhere in the body (if tissue has a receptor) Oxytocin (released from posterior pituitary) |
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Releasing Hormone
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Synthesized by neurons in the hypothalamus
Cause the release of other hormones from anterior pituitary (can also be classified as neurons) Gonadotropin releasing hormone (released by hypothalamus; causes anterior pituitary to release FSH/LH) |
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Gonadotropins
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Release by the gonadotroph cells in anterior lobe
Stimulate gonads FSH, LH |
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Sexual Promoters
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Produced by gonads
Stimulate reproductive tract Regulate function of hypothalamus, anterior lobe of pituitary, behavior |
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Pregnancy maintenance
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Found in high concentrations during times of pregnancy
Maintain pregnancy (progesterone) May assist the female in her lactation ability |
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General metabolic hormones
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Promote metabolic well-being
Thyroxin Adrenal corticoids Growth hormone |
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Luteolytic hormones
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Cause regression of the corpus luteum
Prostaglandin F2(alpha); causes a decrease in progesterone secretion by corpus luteum |
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Peptides
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Small molecules
GnRH |
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Glycoproteins
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Polypeptide hormones (contain carbohydrate moieties)
From anterior lobe: FSH, LH, TSH (thyroid) |
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Inhibin
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Glycoprotein
1 alpha, possibly 2 beta subunits Produced by: sertoli cells in male, granulosa cells in female Supresses FSH activity from anterior lobe |
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Activin
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Produce hormone from follicular fluid
2 Beta subunits Stimulates secretion of FSH in vitro |
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Prolactin
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Protein hormone secreted by anterior lobe
Stimulates lactogenesis Initiates maternal behavior |
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Prostaglandins
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Lipids
Mediate changes in blood pressure (PGE2 lowers, PHF2(alpha) increases) Influences lipid metabolism Mediate inflammation |
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Prostaglandins in Reproduction
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Involved in the control of ovulation
Stimulate uterine smooth muscle |
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Pheromones
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Substances secreted to the outside of the body
Influence reproductive processes Cause specific behavioral or physiological responses (onset of puberty, estrus in females, etc) |
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Endocrine glands
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Compromised of many cells that synthesize and secrete a specific hormone
hormone enters blood hormone is transported to every cell in body only specific cells respond to the hormone (target cells) |
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Hormone receptors
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Have specific affinity for a specific hormone
Contain three distinct regions/domains (extracellular + transmembrane domain = functional; intracellular = non-functional) |
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Extracellular Domain
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Contains specific site that binds to a specific hormone
Transmembrane domain Changes configuration when hormone binds to extracellular domain Activates other membrane proteins (g-proteins) Intracellular domain Function unknown |
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Protein hormone action
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Hormone-receptor binding
G-protein activation Adenylate cyclase activation Protein kinase activation Synthesis of new products |
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Gonadotrophins
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Protein hormones
FSH, LH Bind to follicular cells in ovary Results in synthesis of estradiol |
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Steroid hormone action
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Steroid hormone is transported in blood
Movement of through cell membrane and cytoplasm Binding of steroid to nuclear receptor (transcription factor) mRNA synthesis and protein synthesis |
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Steroid directed synthesis
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Mucus secretion from cervix during estrus
Secretion of uterine ilk from uterine glands Secretion of seminal plasma components from accessory sex glands |
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Strength of Hormone
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Pattern and duration of secretion
Half-life Receptor density (more receptors, more sensitive) Receptor-hormone affinity |
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Episodic Hormone Secretion
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(Like a heart monitor)
Typically associated with hormones under nervous control Nerves in hypothalamus fire (neuropeptides are released in sudden burst) Predictable pattern |
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Basal secretion
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(even, small disturbance)
Tonic secretion Hormone secretion is low Fluctuates with low amplitude pulses |
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Sustained secretion
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hormone levels remain elevated for long periods of time
Steroids tend to be secreted in this manner (high progesterone during pregnancy of diestrus) |
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Receptor Density
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Varies as a function of cell type
Animal condition and nutrition can affect number of receptors The higher the number of receptors, the higher the degree of potential response by target cell |
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Receptor-hormone affinity
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Receptors vary with regards to affinity to various hormones
The greater affinity of the hormone for the receptor, the greater the biological response |
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Hormone analogs
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Similar molecular structures
Agonist, antagonist |
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Hormone agonist
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analog
Bind to specific receptor and initially cause same biological effect as native hormone |
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Hormone antagonist
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Have greater affinity for hormone receptor but will promote a weaker biological activity
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Blood concentrations of hormone determined by
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Secretion rate of hormone
Rate at which hormone is metabolized |
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Metabolism of steroids
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Liver inactivates steroid molecules
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Steroid Metabolites
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Each steroid is metabolized in a different manner
Different metabolites are produced Progesterone produces glucuronide Testosterone produces glucuronide, sulfate salt Appear in urine, feces |
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Protein Hormones
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Pituitary gonadotropins (LH, FSH)
Short half-life Removal of glycosylation from gonadotropin |
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Chorionic gonadotropins
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HCG, eCG
Longer half-life Superovulation in domestic animals |
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Estradiol
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Defeminizes the hypothalamus (which is inherently female); minimizes function of surge center
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Alpha fetoprotein
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Glycoprotein
Binds estradiol Prevents estradiol from crossing blood/brain barrier Estradiol does not have an effect on the female brain |
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Post-pubertal endocrine profile
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Males: LH secretion every 2-6 hours
Females: LH, estradiol surge every 20 days |
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Factors affecting development of hypothalamic GnRH neurons
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Development of threshold body size
Exposure to variety of environment and social cues Genetics |
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Onset of Puberty in Females: Age of First Estrus
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when female become sexually receptive to males
may not reflect true acquisition of puberty (silent ovulation present in heifers, ewes; first ovulation not accompanied by estrus) |
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Onset of Puberty in Females: Age at First Ovulation
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Difficult to determine (palpation, ultrasound, surgical procedures)
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Onset of Puberty in Males: Age when behavioral traits are expressed
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Typically acquired before male is capable of ejaculation
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Onset of Puberty in Males: Age at first ejaculation
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Precedes the ability to produce sufficient spermatozoa to achieve fertilization
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Onset of Puberty in Males: Age when spermatozoa first appear in ejaculate
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Males acquire ability to ejaculate before spermatozoa are available for ejaculation
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Onset of Puberty in Males: Age when Spermatozoa first appear in urine
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Spermatozoa are lost in urine during sexual abstinence
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Onset of Puberty in Males: Age when ejaculate contains a threshold number of spermatozoa
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necessary to have a minimum number of spermatozoa in ejaculate
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Factors affecting onset of puberty
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Development of threshold body size
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Leptin
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Produced by adipocytes
Amount of leptin in the blood is directly correlated to the amount of fat in the body Leptin Receptors: liver, kidney, heart, ekeletal muscles, pancreas, anterior lobe of pituitary, hypothalamus |
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Estrous cycles in sheep
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Usually affected by seasons
Number of hours of light daily governs the release of certain precursors and hormones Length of day decreases = estrous |
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Follicular phase
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Gonadotropin release from anterior pituitary
Preperation of follicles for ovulation |
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During Diesterus
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Low estradiol, high progesterone
Negative feedback on surge center |
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During proestrus
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GnRH is released from tonic center
Growth and development of follicles (produce estradiol) |
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During estrus
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threshold level of estradiol
GnRH is turned on (from surge center) Large quantities of GnRH are released LH surge |
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Estrous cycle
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Follicular phase (20% of estrous cycle)
Luteal phase (80% of estrous cycle) |
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Follicular Dynamics
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Antral follicles develop in response to tonic levels of FSH and LH
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Dominant follicle
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Large preovulatory follicle inhibits other antral follicles from being recruited
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During metestrus
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Group of follicles is recruited (first wave)
Endocrine conditions are not favorable |
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During diestrus
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Second follicular wave occurs (group of follicles is recruited)
Endocrine conditions are still not favorable |
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During follicular phase
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Third follicular wave occurs
Endocrine conditions are favorable |
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During luteal phase
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Dominant follicle can ovulate if luteolysis occurs
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Recruitment (proestrus)
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FSH levels increasing (promote growth of follicle)
Recruiting a group of follicle |
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Selection (proestrus)
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Selected follicles secrete estrogen and inhibin (inhibit FSH secretion from anterior lobe of pituitary)
Lower FSH secretion Higher LH secretion |
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Dominance (estrus)
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Largest follicles secrete more estrogen and inhibin
LH surge Inhibin inhibits FSH secretion (smaller antral follicles undergo atresia/close) |
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Granulosal Layer
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Separated from theca interna by a thin basement membrane
Contains FSH receptors Produce: estrogen, inhibin, follicular fluid |
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During follicular development
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Follicle contains LH-specific membrane receptors (located on theca interna)
LH binds to LH-specific membrane receptors Cholesterol is converted to testosterone Testosterone diffuses out of theca interna, enters granulosal cells Granulosal cells have FSH receptors (FSH binds to receptor; testosterone is converted to estradiol) |
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Major effects of estrogen on reproductive tract
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Increased blood flow
Genital swelling Change in tissue electrical conductivity Leukocytosis Increased mucosal secretion Initiation of uterine gland growth Elevated myometrial tone |
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Menopause
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Termination of menses
Reproductive cyclicity stops Reduction of estrogen, progesterone, inhibin Normal function of hypothalamus and pituitary |
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Effect of follicular depletion
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Declining blood levels of estrogen
Declining levels of progesterone Decrease in number of follicles no LH surge |
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Estrogen deficiency
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Genital atrophy
Decreased secretion by reproductive tract Modification of lipid metabolism and of the vascular walls Increase in physiological loss of bone (osteoporosis) Vasomotor symptoms (hot flashes) |
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Ovulation
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Begins with LH surge (cells in theca interna produce progesterone instead of testosterone)
Progesterone stimulates the synthesis of collagenase by the theca interna Collagenase (breaks down collagen) Tunica albuginea contains connective tissue that is broken down Volume of follicular fluid increases |
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After LH surge (ovulation)
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Synthesis of prostaglandin F2(alpha) and E2
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Prostaglandin F2(alpha)
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Stimulates contractions of smooth muscle component of ovary
Stimulates lysosomes to rupture, release enzymes which may help break connective tissue |
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Prostaglandin E2
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Helps to remodel the CL after ovulation
May activate plasminogen A substrate Is converted to plasmin by plasminogen activator Helps to dissolve the coagulum of the corpus hemorrhagicum and remodels the follicle into a CL |
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Superovulation
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Abnormally high number of follicles are induced to grow and ovulate
Administration of exogenous gonadotropins (equine chorionic gonadotropin, FSH) followed by adminstration of LH, GnRH |
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Phases of oocyte maturation
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Mitotic division of primordial cells
Nuclear arrest Cytoplasmic growth Resumption of meiosis |
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Luteal Phase (estrous cycle)
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Begins (ovulation)
Ends (luteolysis; regression of CL) Dominant hormone: progesterone CL originates from ovulatory follicle |
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Luteal tissue
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Large cells (from granulosa cells)
Small cells (from theca interna cells) |
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Factors that may affect the vigor of CL
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number of luteal cells
degree to which the CL becomes vascularized |
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Cellular changes that may affect enlargement of CL
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steroidogenic cells, non-steroidogenic cells
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Steroidogenic cells
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Luteal cells undergo hypertrophy (increase in size)
Small luteal cells undergo hyperplasia (increase in cell numbers) |
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Non-steroidogenic cells
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Increase number of fibroblasts, capillary cells, eosinophils
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Factors that may affect the functional capability of CL
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Degree of vascularity in cellular layers of follicle
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Insufficient luteal function
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poor progesterone synthesis and secretion
Contributes to reproductive failure uterus unable to keep pregnancy |
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Estrus
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Part of the follicular phase of estrous cycle, when an animal will stand to breed
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Estrous
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Cycle of a non-pregnant female mammal that goes through a luteal phase and a follicular phase
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Polyestrus
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Ovulating more than once a year (ex. with the seasons)
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Monoestrus
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Only one breeding season a year
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Luteal phase
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Latter half of the estrous cycle, starting with formation of CL and ending with either pregnancy or luteolysis
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Follicular phase
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Phase during which ovary matures, ending with ovulation
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Proestrus
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GnRH is released from tonic center
Follicles are starting to grow, produce estradiol |
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Estrus
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Threshold level of estradiol
GnRH is turned on from surge center (large quantites of GnRH are released; LH surge) |
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Metestrus
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CL starts to form
Small amounts of progesterone are secreted |
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Diestrus
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Low estradiol, high progesterone
Negative feedback on surge center |
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Estrous Cycle: Bitch
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Length of Reproductive Cycle: 6 Months
Reach Sexual Maturity Between 8-18 months of age Proestrus: 9 days (bloody discharge, not fertile) Estrus: 5-21 Days Diestrus: 56-58 Days (pregnant), 60-100 Days (non-pregnant) Anestrus: 4-5 Months |
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Estrous Cycle: Queen
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Require 12 or more hours of light a day to maintain normal cyclicity
Puberty: 9-10 Months Proestrus: 1-2 Days Estrus: 3-16 Days Interestrus/Postestrus: Period between estrus if ovulation does not occur (2-3 weeks) Diestrus: 35-40 Days Anestrus: Time between cycles (depends on light/season) |
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Estrous vs Menstrual Cycle
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Estrous cycles typically continue until death. Animals usually are only sexually active during the appropriate portion of the estrous cycle, and reabsorb the endometrium if pregnancy does not occur. Menstruation sheds the endometrium, and mammals that menstruate can and do have sex at any point in the cycle. Menstruating mammals end their cycle with menopause.
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Amenorrhea
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Absence of a menstrual period, as seen during pregnancy and lactation, during childhood, and during/after menopause.
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