Female Reproductive System, Lecture notes of Anatomy

Download Female Reproductive System and more Lecture notes Anatomy in PDF only on Docsity! Female Reproductive System ANS 215 Physiology and Anatomy of Domesticated Animals I. Function: Perpetuation of the Species A. Production and development of oocytes B. Provide an environment for the growth and nourishment of the developing fetus after fertilization. C. Synthesis of hormones II. Anatomy: Ovaries, Uterine Tubes, Uterus, Vagina, and Vulva A. Ovaries – two 1. Paired glands that provide for the development of oocytes 2. Production of hormones 3. Suspended from the dorsal wall to the abdomen by the mesovarium a. part of the broad ligament 4. Easily manipulated by rectal palpation 5. Almond-shaped in most species - Bean-shaped in horse – Berry-shaped in the sow 6. Ovulation – release of oocyte occurs over the entire surface in most species a. in the horse they are confined to one site – Ovulation Fossa (indentation) Reproductive tract of the cow (corsal aspect). the body of the uterus, vagina, and vulva (vestibule of the vagina) have been laid open and the right ovary withdrawn from the infundibulum. The broad ligament (a downward reflection of the peritoneum) suspends the reproductive tract from the dorsolateral abdominal wall. 1 Cranial view of bovine female reproductive ortans. The broad ligament is the inclusive term for the mesovarium, mesosalpinx, and mesometrium that suspend the ovary, uterine tubes, and uterus, respectively, from the dorsolateral wall of the sublumbar region. The broad ligament is a reflection from the peritoneum. Ovarian differences resulting from species morphology and functional changes. A. Sow ovary (berry- shaped). B. Cow ovary (almond-shaped) with ripening follicle. C. Cow ovary with fully developed corpus luteum. D. Mare ovary (kidney-shaped) with ovulation fossa (indentation). 7. Structure of ovary a. epithelium – surface layer b. tunica albuginea – connective tissue covering the entire ovary c. cortex – beneath tunica albuginea i. contains follicles in various stages of development d. medulla – loose connective tissue, blood vessels, lymphatics, and nerves 2 9. Corpus Luteum (CL) a. formation after ovulation of follicle by rapid vascularization of granulosa cells b. produces progesterone – hormone of pregnancy B. Uterine Tubes – Fallopian Tubes 1. Paired, convoluted (coiled) 2. Avenue to transport oocytes from ovaries to uterus 3. Site of fertilization 4. Preceeded by fimbriae and infundibulum a. fimbriae assist in directing the oocyte into the infundibulum 5. Lined with both secretory and ciliated cells for the movement of both oocytes and spermatozoa 6. Has both circular and longitudinal muscles which also aid in transport of oocytes and spermatozoa 7. Supported by a continuation of the mesovarium C. Uterus – location for the developing fetus 1. Consists of corpus (body), cervix (neck), and two coruna (horns) 2. Tussue layers a. endometrium - highly glandular over entire lining except ruminants * ruminants have mushroom-shaped projections called caruncles where fetal membranes attach, the fetal sides are called cotyledons - varies in thickness and vascularity under the influence of both hormonal changes and pregnancy - glandular secretions provide nutrients to the embryo before implantation and development of placenta b. myometrium – muscular portion of the uterus - hypertrophy (increased cell cize) and hyperplasia (increased cell numbers) during pregnancy - primary function is in aiding the expulsion of the fetus c. serous covering for support (mesoderm) - provides suspensory support for the uterus - two broad ligaments on from each side that support the uterus and varies structures on their respective sides 5 Position of the cow’s uterus at the third and sixth month of pregnancy. A. Superimposed uterus and ovary (left) (note the location of the ovary – gold color) represents the uterus at the third month of pregnancy. B. Cross-seciton of uterus at the sixth month of pregnancy with its contained fetus relative to the adjoining abdominal viscera (rumen on left and uterus on right side of abdomen). d. cervix – heavy, smooth muscle sphincter - tightly closed except during estrus and parturition - secretes outward flowing mucus from goblet cells * mucus flow prevents infective materials from entering the uterus from the vagina e. vagina - within the pelvis, between the uterus and vulva - sheath for male penis during copulation - urethral open of discharge of urine - passage of fetus during parturition f. vulva (vestibule of the vagina) – caudal portion of the female genitalia - located from the urethral opening to the exterior of the genitalia - clitoris (femal vestigal counterpart to the male penis) * erectile tissue * sensory nerve endings g. labia – external portion of vulva 6 Location of reproductive organs relative to the rectum and urinary bladder. A. Cow, B. Sow, C. Mare, D. Bitch. Note species differences in anatomy of the cervix and mammary gland(s). 7 Relationship of the ovarian artery of a ruminant and its branches (1) to those of the uterine vein (2). The intertwining ensures a large area of contact. III. Hormones of Female Reproduction A. Estrogen – Steroid 1. Produced by granulosa cells of the follicles on the ovaries 2. Major roles: a. stimulate endometrial gland growth b. stimulate duct growth in mammary gland c. increase secretory activity of the uterine tubes d. initiation of sexual receptivity e. regulation of PGF f. early union of epiphysis – ceasing of long bone growth B. Progesterone – Steroid (Hormone of Pregnancy) 1. Produced by corpus luteum (CL) – yellow body 2. Major roles: a. promotion of endometrial gland growth b. stimulation of secretory activity of the oviduct and endometrial glands to provide nutrients for the developing embryo before implantation c. stimulate mammary gland growth d. prevent contractility of uterus during pregnancy e. regulate secretions of gonadotropins 10 C. Gonadotropins – Glycoprotein – (‘gonad-‘ gamete producing, ‘-tropin’ stimulating effect) 1. Produced and secreted by anterior pituitary a. follicle stimulating hormone (FSH) - stimulates follicle growth b. luteinizing hormone (LH) - ovulation of follicle - luteinization of granulosa cells to form corpus luteum (CL) * luteinization – hypertrophy and vascularization of the ovulatory site D. Luteinizing Hormone Releasing Hormone (LHRH)/Gonadotropin Releasing Hormone (GnRH) (same hormone, two different names) - Peptide 1. Secreted from the hypothalamus a. into the blood stream to affect a response in the anterior pituitary to secrete LH and FSH E. Prostaglandins – Eicosanoids – PGF2 specifically 1. Secreted by the uterus 2. Transported to the ovaries via uterine vein then diffusion across to the ovarian artery – an important mechanism, one pass through the lungs breaks down PGF2 3. Brings about the demise of the CL 11 IV. Ovarian Activity and Follicular Growth A. Puberty – beginning of reproductive life 1. Beginning of ovarian activity 2. Hormone dependent development of Graafian follicles from growing follicles a. under the cyclic influence of LH and FSH which are released in response to the release of GnRH (LHRH) from the hypothalamus - LH and FSH which are then secreted from the anterior pituitary - at the same time on the ovary the interstitial cells begin to surround the basement membrane of the granulosa cells to form the theca interna and theca externa, these cells then become vascularized with a capillary bed - capillaries increase in size and are located next to the basement membrane - LH receptors form on the granulosa cells - under the influence of LH – androgens are produced by the thecal cells which cross the basement membrane, then the granulosa cells, under the influence of FSH, convert these androgens to estrogen - under the influence of estrogen, the antrum of the follicle is formed - FSH also stimulates the formation of LH receptors on the granulosa cells - the surge in LH, approximately 24 hours before ovulation, causes a reduction of FSH receptors that bring about a decrease in the conversion of androgens to estrogen - the LH receptors on the granulosa cells, which convert to luteal cells after ovulation, will produce progesterone - this site of ovulation now is called a corpus luteum (CL) 12 ovarian activity and uterine involultion (involution - return to normal) VII. Fertilization and Pregnancy A. Transportation of oocyte and spermatozoa 1. oocyte is caught by the contractile fimbriae 2. within oviduct, the oocyte is moved by cilia and oviduct motility 3. spermatozoa, released by ejaculation of the male, travel to the oviduct via uterine contractility among other mechanisms 4. spermatozoa are caught in various uterine structures (crypts and folds) to assure viable sperm present the time the oocyte is present in the oviduct a. reservoirs at the junction of the uterine body and the uterine tubes 5. spermatozoa must undergo capacitation a. changes necessary for penetration of the zona pellucida and subsequent fertilization of oocyte i. requires several hours – 8 hrs. in the bovine 6. ovulation occurs after the onset of sexual receptivity (estrus) – allows time for capacitation to take place 7. oocytes are viale for 12 – 18 hrs. 8. spermatozoa are viable for 24 – 48 hrs. (cow, ewe, and sow), up to 90 hrs. for bitch and 120 hrs. for a mare B. Fertilization is the fusion of male and female gametes, oocyte and spermatozoa 1. Penetration of zona pellucida by sperm 15 a. enzymes involved: hyaluronidase and acrosin b. meiosis resumes and second division takes place c. once penetration takes place, the zona reaction takes place to prevent more spermatozoa from entering the oocyte d. pronuclei develop from each gamete, they join creating a nucleoli where the haploid number of chromosomes unite creating a full compliment e. the zygote remains in the uterine tube for 3 – 4 days, then the developing CL must be fully functional for the zygote to survive in the uterus 1. progesterone is the hormone of pregnancy - minimizes uterine contractions that are present during estrogen dominance of the estrous cycle - causes the development to the glandular endometrium that secretes uterine milk to nourish the developing embryo before implantation f. 16 – 32 cell stage of the developing embryo is called the morula g. a cavity forms within the morula by day 6 – 8 and the cell mass is called the blastocyst 2. three phases or stages a. oocyte period i. until blastocyst attaches to endometrium ii. nutrition from yolk sac and uterine milk b. embryonic period i. until about day 45 ii. rapid growth – major tissues, organs, and systems iii. become recognizable by ultrasound iv. nutrition from mother = uterus and the developing placenta 3. placentation a. development of extraembryonic membranes b. three parts 16 i. chorion - outer layer next to the endometrium or the outermost tissue ii. allantois - middle layer which fuses with the chorion iii. amnion - the innermost layer - envelops the fetus and contains fluid derived from fetal urine and respiratory secretions * the amniotic fluid protects the fetus from external shock * prevents adhesion of fetal skin to the amnion * aids in dilation of the cervix and lubrication during parturition Fetus of horse within the placenta. The chorioallantois is the combination of the allantois with the chorion. Umbilical arteries and veins ( not shown) occupy the space between the outer allantois and chorion. The chorion is associated intimately with the endometrium. The inner allantois is fused with the amnion. c. types of placentation i. diffuse – attachment is continuous throughout the entire surface of the endometrium - horse and pig ii. cotyledon – attach at mushroom-like structure throughout the endometrium - ruminants such as the cow, sheep, and goat 17