Fertilization Male Learning Objectives Gametogenesis Lactation 280 Days 8-10 months -Anestrous To learn the different structures and nomenclatures for the parts of the female reproductive system. To learn the basic functions for the different parts of the tract and how they work together. 40-60 Days 21 Days Spermatogenesis Rectum Suburethral Diverticulum Uterus Ovary Vulva Vagina Pelvis Cervix Broad Ligament Bladder Oviduct Uterine Body Uterine Horn Overall functions for the female reproductive tract Ovary Oviduct Control activity of organs (hormonal) Cervix Vagina Blind pocket Bladder Membrane lines Hymen Mare - Transurethral Fold Urethra Clitoris - Endocrine function Suburethral Diverticulum Vulvo-vaginal sphincter muscle Vestibule Ovary, uterus, fetus, placenta, pituitary - Example: Estrus Transport sperm Stimulation of myometrial contractions Produce oocyte Female Gamete (Diploid) Facilitate fertilization - Sperm passage from uterus to oviduct Provide environment for embryo and fetus Early oviduct, uterus the remainder of pregnancy Labia Majora 1 Ovaries: Give birth to fetus Germinal Epithelium - Surface Epithelium Corpus Luteum Medulla Continuous with peritoneal lining Cuboidal Cells - prevent adhesions Are not true germ cells Broken at ovulation Cortex Dilation of cervix, Strong uterine contractions Recycle to become pregnant again Tunica Albuginea Involution of uterus, return to positive energy balance Dense connective tissue layer Provides structure to ovary Provide nutrients to young Cortex- Contains Female germ cells Germinal - Oocytes - mature oogonia Epithelium - Follicles - Corpora lutea (pl), Corpus luteum (Sing) Lactation - Stimulate mammary gland development Tunica Albuginea Medulla - Contains connective tissue, blood vessels lymphatics, nerves Mare has an inversion of cortex and medulla Ovarian functions: Ovulation can occur on any point of the cow, ewe and sow ovary (Cortex layer on outside) The mare ovary has an inversion of the cortex and medulla (outside layer). Therefore, ovulation can only occur at the Ovulation Fossa Produce estrogens (Follicles) - Large Tertiary or Graafian Follicle Induces Estrus Activity Contains oocyte - Diploid (2N) Graafian Follicle Blood vessels and connective tissue in medulla Produce progesterone Corpus luteum forms from ovulated follicle Functions to prepare uterus for pregnancy and is essential to maintenance of pregnancy in all species Internal CL Structures within the Ovary Graafian Follicle Ovum Secondary Oocyte (1N) Ovulates Tertiary Follicle Stroma Primary oocyte (2N) Corpus Luteum Produces Progesterone Single Cell Largest cell of body 180 µm (2N) Nucleus Primary follicle Proliferating primary Two or more follicular layers Increase in size of oocyte and Height of follicular cells Secondary follicle Ooplasma Follicular Cells Vitelline Membrane Primary Oocyte Surrounded by several layers of follicular (Granulosa cells) Corpus Hemorrhagicum (Bloody body) Primary oocyte Stage of the majority of follicles Resting Stage Ruptured Follicle Forms from ovulated Follicle Young animal may have 20,000-30,000 oocytes after puberty Primary Follicle CL regresses Secondary Follicle Atretic Follicle Corpus Albicans Fate of most Dead CL Follicles Tertiary follicle Follicle forms a fluid filled cavity Differentiation of several distinct cell layers in the follicle wall Antrum Primary Oocyte 2 Theca Externa Line outside layer of follicle wall. Composed of connective tissue, and blood vessels Graafian Follicle Theca Interna Antrum Cavity contains follicular fluid serum like Large Ovulatory Follicles of the Sow Cow Graafian Follicle Granulosa cells which surround the oocyte. This layer of cells released with oocyte after ovulation. Important for ovum transport in oviduct Middle layer of cells on follicle wall. Function Produce testosterone which is converted to estrogen by the granulosa cells. (Two Cell Theory) Line inside of follicle wall. Support and control of oocyte development Cumulus Oophorus Zona Pellicuda (2N) Granulosa Cells Primary Oocyte Follicle Wall - Graafian Follicle Stroma FSH & LH Receptors Follicular Basement Membrane Fluid Theca Externa Layer Zona Pellicuda Estrogen Corona Radiata Theca Interna Layer Granulosa cells produce estrogen from testosterone Theca Interna cells Produce - Testosterone LH Receptors Stimulated by Hormones FSH and LH Granulosa Layer Hormones released from the brain Antrum LH and FSH Blood supply Ovarian Single granulosa cell layer that is in direct contact with zona pellucida of oocyte Capillary Corpus luteum Corpus Hemorrhagicum Luteal Cells Collapsed follicle - Contains blood, lymph, granulosa and theca cells Sow Internal CH Mare Solid tissue which is composed of luteal cells that originate from granulosa and thecal cells of the Graafian Follicle Function to produce Progesterone that: 1) Inhibits estrus and parturition 2) Blocks myometrial contractions 3) Stimulates endometrial secretion of nutrients 4) Stimulates the production of a luteolytic agent to Kill the CL if no embryo is present. Prostaglandin F2α 3 Corpus albicans Ovarian Changes During the Estrous Cycle: Regressed or degenerate corpus luteum. Causes a drop in blood progesterone. Composed of connective tissue which has no function (Scar tissue). Continue to get smaller with each day until they are not necessarily even visible Secondary Follicle Prepare for future cycles - continues growth - Expression Graafian Follicle Estrus of heat, stands to be Corpus Albicans mounted Ovulation of oocyte Rapid growth to Graafian follicle High Estrogen Developing large Tertiary follicle Corpus Hemorrhagicum DAY 1 19-21 18 Regressed CL No progesterone production Filled with blood and lymph Progesterone is still low 2-3 Days of the Bovine Estrous Cycle Uterine Horn Oviduct Isthmus Utero-Tubal Junction Second 1/2 of oviduct 1. Few folds in lumen 2. Few ciliated epithelial cells 3. Small diameter 4. Very muscular Point where the uterine horn meets the oviduct Functions to block polyspermy Ampullary-Isthmic Junction Site of Fertilization Ostium - opening to oviduct Funnel shaped - covers the ovary to pick-up ovum Infundibulum 4-5 21 Days Regressing Corpus Luteum If not pregnant release of PGF2α from uterus causes CL death Developing Tertiary Follicle Ampulla First 1/2 of oviduct Cilia 10-17 6-7 7-10 Early Corpus Luteum Increasing Progesterone in blood Mature CL - Progesterone high Oviductal functions: Ovary Fimbria Cumulus oophorus surrounding ovum aids in pick-up by the fimbria lining the infundibulum 1. Many folds 2. Ciliated epithelium 3. Large diameter 4. Not very muscular Petal-like structure Lines the infundibulum Contains ciliated cells to move ovum Follicle Ovulated Graafian Follicle releases ovum Publication permission granted by Dr. Richard J. Blandau from original films by the University of Washington Transport oocyte to site of fertilization Taken School of Medicine-Ovulation and Egg Transport in Mammals Sperm will continue Transport sperm to site of fertilization out through oviduct Isthmus- Fluid towards ovary into peritoneal cavity Utero-tubal junction is tight Muscle contractions toward ovary Ampulla - cilia beat towards uterus Reduce sperm numbers to prevent polyspermy Bull deposits 7 X 109 sperm in vagina - only a few 100 in isthmus and AIJ Isthmus serves as a reservoir until sperm released to AIJ Remove oocyte from surface of ovaryPublication permission granted by Dr. Richard J. Blandau Taken from original films by the University of Washington School of Medicine - Ovulation and Egg Transport in Mammals; Ligaments contract - move ovary (Mesovarian), oviduct (Mesosalpinx), and infundibulum (mesotubarium superius) Allows cilia on fimbria to come in contract with cumulus and oocyte Cilia of ampulla and fimbria Smooth muscle contractions may also play a role Provide proper environment for oocyte, sperm & fertilization Secretions from epithelial cells lining ampulla help prepare sperm for fertilization (capacitation) and aid in early development of egg - Secretions stimulated by estrogen are unique to estrus phase of cycle Transport & facilitate development of early embryo After fertilization, zygote remains in isthmus or ampullaryisthmic junction for 2-5 days, until lumen of isthmus dilates to allow passage into uterine horn. Muscular contractions move ovum into uterus rapidly Embryos held in oviduct to allow time for uterus to prepare for implantation 4 Components of the uterus: Horns Advanced Duplex (Opossum) Two cornua Length: Pig - 4 to 5 ft (Bicornuate) Cow - 7 to 8 in (Bipartite) Duplex (Rabbit, Mouse) Bicornuate (Pig) Two Uterine Horns Two Uterine Horns Two Uterine Horns (long) Two Cervices Two Cervices Body Two Vaginas Fusion between horns (common opening to both) Allows transuterine migration in ewe, mare and pig Site of semen deposition in mare and sow, also AI One Vagina Smaller Uterine Horns Bipartite (Cow, Ewe, Doe) Layers in wall of uterus Three distinct layers in oviduct, vagina and uterus Outer - perimetrium Outer serous layer continuous with peritoneum - blocks adhesions Middle - myometrium Inner circular layer of smooth muscle outer longitudinal layer Peristaltic contractions Inner - endometrium Provides point of placental attachment and glands provide secretions for embryo development (Estrogen and Progesterone) Modified Bipartite (Mare) Estrogen stimulates uterine secretions which capacitate sperm Provides environment for embryo Uterine secretions stimulated by estrogen and progesterone Proper timing of embryo and uterus is important for embryo transfer Components of Cervix Uterine Body Crypts At birth expels fetus Strong rhythmic myometrial contractions (Progesterone low) Recovers from pregnancy Uterine involution - myometrial contractions and enzymatic activity shrink uterus back to normal size Makes the corpus luteum regress If not pregnant, uterine endometrium releases Prostaglandin-F2a(PGF2α) to cause the CL to regress If pregnant - embryo provides a chemical signal which allows CL to be maintained No Uterine Horn, All Uterine Body Simplex (Human) Larger Uterine Body with Smaller Uterine Horns Functions of uterus: Transport sperm - when female is in heat Estrogen stimulates myometrial contractions so that sperm move to site of fertilization Muscle contractions Towards oviduct during estrus (heat) but following ovulation are towards cervix until progesterone increases from CL Sperm motility Viable sperm (motile) are important so that they are not absorbed Absorption and phagocytosis Occurs by uterine epithelium and leukocytes which fight infection Partially prepares sperm for fertilization Supports development of fetus Quiescent myometrium - Progesterone Immunological protection from rejection by maternal immune system Common Uterine Body One Cervix One Vagina Fold COW Cervix is very hard and rigid during estrus Composed of thick connective tissue Cervix Cow has 4-5 annular rings Cervix tightly closed except during estrus Mucus characteristics change during estrous cycle Estrus - clear, watery long parallel strands (Estrogen) Diestrus - little mucus Jelly-like mucus crossed linked by disulfide bonds (Progesterone) Longitudinal Folds Contain crypts which provide surface area for sperm reservoir Os Cervix Fornix Vagina Present in mare, ewe and cow Vagina Mucus discharge during estrus 5 Mare SOW Uterine Body Uterine Body There are no obstacles in the mare after the fornix vagina Cervix Mare is opposite of other species as cervix is soft and pliable during estrus flattens on floor Vagina of vagina. During pregnancy is tight and closed Fornix of Mare Longitudinal Folds Cervix Cervix Sow cervix has many interdigitating pads Note: Sow does not have fornix vagina Fornix Vagina Os Cervix Os Cervix Os Cervix Vagina Fornix Vagina Vagina Functions of the Cervix: First sperm barrier in cow and ewe Not involved in sow and mare Transport sperm Long strands of mucus Under estrogen mucus is thin and watery. Sperm enter parallel stands of mucus in vagina and are transported into cervical folds and crypts. Conditions in cervical mucus favor sperm motility. Muscular action of vagina and cervix may help movement Stallion & Boar ejaculate through the cervix Stallion glans penis bells out and expands cervix Force of ejaculation sends semen directly into uterus Stallion Boar Boar has a corkscrew penis Glans penis locks into the interdigitating pads of cervix Volume of semen (300-400 ml) moves into uterus Utero-tubal junction is much more functional in sow to control sperm numbers entering oviduct Functions of Vagina: Copulatory organ - Fornix vagina site of semen deposition (Cow and Ewe) No glands - Secretions come from passage of plasma components as well as cervix Provides lubrication pH is acidic (5.7) - Bacteriostatic Stimulates glans penis of bull temperature and pressure Birth Canal - Dilates for fetus during parturition Functions of Vestibule: Common duct for urine & reproduction Stimulates male for copulation Passage for fetus during parturition Vulva-vaginal sphincter muscle behind urethra contracts to block urine from entering uterus Mare - Has a transurethral fold to direct urine out Barrier to sperm Mucus and anatomy of cervix act as a sperm filter Prevents large numbers of sperm from reaching oviduct in cow and ewe Reservoir for sperm Sperm enter crypts and folds which protect them for a long period of time as it is a favorable environment for sperm survival as they move into uterus. Majority of sperm (90%) is lost out of the vagina Blocking bacterial invasion during pregnancy Mucus highly crossed-linked, cervix constricts Leukocytes present to kill bacteria Birth Canal Cervical plug liquidifies and cervix dilates to permit fetal expulsion at parturition Transurethral Fold Bladder Urethral Opening Clitoris Vulva 6 Vestibular glands may contribute to lubrication during estrus Pheromones - airborne chemical messages odor attracts male or female Functions of Clitoris: May control a response to copulation in female Sensitive to neural stimulation Oxytocin release from brain Journey Through the Mare Reproductive Tract 7
