Female Reproductive Anatomy

• The text contains study notes on female reproductive anatomy.
• Dr. Jen Clulow is acknowledged.

Learning Objectives

• Ability to draw and label the female genital tract's anatomy.
• Ability to identify the anatomy of the female genital tract and its supportive structures.
• Capacity to describe the female genital tract's composition grossly and histologically.
• Skill to identify and describe similarities and differences in the female tract among domestic species.

Lecture Overview

• Focus on an overview of female reproduction and anatomy.
• Discussion of the functions of the female reproductive tract.
• Examination of female reproductive tract structure.
• Study of ligaments associated with the female reproductive tract.
• Consideration of changes in the female reproductive tract.
• Comparison of different reproductive tracts.

Importance of the Female Reproductive Tract

• Used in reproductive medicine for inserting things.
• Involved in obstetrics and artificial breeding (e.g., embryo transfer).
• Aims to maximize productivity by making it work efficiently.
• Used in diseases treatment like neoplasia (cancer), infections, and conformation aberrations.
• Can be medically stopped working (GnRH vaccines, GnRH agonists) or surgically (spaying or ovariohysterectomy).
• Used in controlling normal function by synchronizing for embryo transfer/artificial insemination.

Functions of Female Reproductive Organs

• Gamete production and transport involving the ovaries, uterine tube, and uterus.
• Hormone production by the ovaries, uterus, and placenta.
• Organ of copulation: vulva, vestibule, and vagina.
• Site of fertilization and attachment: uterine tubes and uterus.
• Support and expulsion of conceptus: uterus and feto-placental unit.
• Nourishment of the neonate: mammary gland.

Structure of the Female Reproductive Tract

• Similar basic structure among domestic species.
• Ovaries are the female gonads.
• Uterine tubes : oviduct/fallopian tube.
• Uterus consists of uterine horns and the uterine body.
• Other structures include the cervix, vagina, vestibule, vulva, and clitoris.

Sexual Development - Female

• No DHT (Dihydrotestosterone).
• No accessory sex glands.
• Urogenital sinus develops into the vestibule of the vagina.
• The genital tubercle becomes the clitoris.
• Genital swelling becomes the vulva.
• The degree of fusion of embryonic structures varies by species.
• There is considerable variation between species.

Development of the Uterus

• Formed by the fusion of paramesonephric ducts (Müllerian duct).
• Paramesonephric ducts develop into future uterus, cervix, and vagina.
• Formed by the fusion of the urogenital sinus (UGS).
• Urogenital sinus develops into future bladder, urethra, and vestibule.
• The urachus forms from the UGS.

Uterine Types

• Bicornuate uterus has poorly to moderately developed uterine horns; seen in mares and cows.
• Bicornuate uterus has highly developed uterine horns; seen in female canids like bitches, queens, and sows.
• Simplex uterus has no uterine horns; found in primates.
• Duplex uterus has two cervices and is found in marsupials and rabbits.

Ovary

• Consists of the tunica albuginea and the ovarian cortex.
• The ovarian cortex contains oocytes, follicles, corpus luteum (CL), and corpus albucans (CA).
• Consists of the ovarian medulla.
• The ovarian medulla consists of vaculature, nerves and lymphatics

Oogenesis

• Maturation of oocytes occurs throughout the follicular phase.
• Mitotic and meiotic divisions occur prenatally.
• Nuclear arrest occurs in primary oocytes.
• Meiosis resumes at puberty.
• A pubertal LH surge resumes meiosis.
• The nucleus of the oocyte migrates towards the periphery of the plasma membrane.
• The first polar body forms just before ovulation.

Follicular Structure of the Ovary

• Primordial follicle consists of quiescent cells in the peripheral cortex, contains a single primary oocyte, and is surrounded by a single layer of flattened squamous follicular cells.
• Primary follicle has a single layer of cuboidal cells and can develop into a secondary follicle or regress.
• Secondary follicle has two or more layers of cuboidal cells and lacks an antrum/cavity or follicular fluid.
• Tertiary follicle (secondary vesicular follicle) contains a fluid-filled antrum.
• A mature (Graafian) follicle appears as a large, protuberant tertiary follicle.
• It may have more than one layer if polyovular (or fertility drugs are used).
• Consists of three distinct layers: theca externa, theca interna, and granulosa.
• Regnier de Graaf (1641-1673) was a Dutch reproductive biologist.
• Oogenesis is the formation and development of female gametes (oocytes).

Atresia

• Pro-oestrus stage involves the development of several follicles in both monovular and polyovular species.
• Most follicles regress/degenerate, a process called atresia.
• During early atresia, the oocyte liquefies, and the zona pellucida folds.
• Late Atresia occurs forming a corpus atreticum.
• Polyoocytic follicles exist and may degenerate.

Corpus Luteum (CL)

• The corpus hemorrhagicum involves the collapse of follicular walls and hemorrhage into the antrum.
• Corpus luteum is the "yellow body".
• Granulosa and theca interna cells are involved.
• Vasculature invades the clot to form a highly vascular gland.
• Lutenisation occurs.
• Two cell types predominate: granulosa lutein cells (producing progesterone) and theca lutein cells (producing androgenic precursors).
• Luteolysis is the end of dioestrus, occurring if fertilization has not occurred.
• Hormonal influences stimulate this, leading to the formation of corpus albicans.
• If fertilization and maternal recognition of pregnancy occur, the CL produces progesterone (P4) for part or throughout the gestation.

Mare Ovaries

• The cortex and medulla are reversed.
• Ovulation occurs through the ovulation fossa.
• Kidney-shaped ovary.
• Follicles and corpora lutea are centrally located.
• Mature follicles rupture into the ovulation fossa.
• Follicles rupture through the cortex in other species.

Uterus

• Three distinct layers: endometrium (mucosa), myometrium (muscularis), and perimetrium (serosa).
• The lamina propria and submucosa are connective tissue with associated vessels and nerves.
• 3 main layers: endometrium, myometrium, and perimetrium.
• The endometrium is the mucosal layer.
• The myometrium is the muscular layer
• The perimetrium is the serosal layer.
• There is no submucosa.
• Theuterus breaks all the rules; endometrium, myometrium, and perimetrium approximate with mucosa, muscularis, and serosa.

Ligaments of the Female Reproductive Tract

• The reproductive tract is supported by the "broad ligaments," both left and right.
• The broad ligaments attach the reproductive tract to the lumbar region of the abdominal roof or pelvic walls.
• Blood vessels and nerves run within the broad ligaments.
• Each broad ligament has three parts: mesovarium (supports the ovary), mesosalpinx (supports the uterine tube), and mesometrium (supports uterus).
• Functions of the broad ligaments:
  • Support and position reproductive organs.
  • Carry blood vessels and nerves to reproductive organs.
• The uterus has additional ligamentous support via the mesometrium, round ligament, and intercornual ligament.
• The most important support for the uterus is the mesometrium (L & R).
• The round ligament is a thin cord that lies in a fold of the mesometrium.
• The round ligament is a remnant of the gubernaculum
• The round ligament travels from the tip of the uterine horn to the inguinal canal.
• The intercornual ligament is dorsal and ventral.
• The intercornual ligament is between the uterine horns in cows.

Reproductive Blood Supply - Ruminants and Pigs

• Aorta → Internal iliac a. → Internal pudendal a. → Uterine a.
• Arterial Supply: UTERINE a. (main supply), Ovarian a. → uterine branch, Vaginal a.
• Features: Caruncles are very vascular (ruminants), Uterine a. enlarges during pregnancy – can palpate "fremitus" in the cow.

Cervix

• The cervix is very thick-walled and facilitates sperm transport.
• Sperm transport depends on mucus characteristics.
• The cervix acts as a sperm reservoir and sequesters sperm in cervical crypts.
• It prevents excessive sperm numbers and allows selection of viable sperm.
• The cervix acts as a barrier between the sterile uterus and non-sterile vagina, influenced by P4 and E2.

Changes in the Female Repro Tract

• Changes in the female reproductive tract occur throughout life in response to hormones and pregnancy.
• Long-term changes include puberty, old age, and physical changes associated with gestation.
• Short-term changes include each oestrous cycle and changes with pregnancy and parturition.

Comparative Uteri - Canine

• Short uterine body and long, straight uterine horns in canines.
• Extensive mesometrium which allows movement of the uterine horns.
• Canine uteruses have a short cervix.
• Uterine blood vessels rupture during pro-oestrus, causing bloody vulval discharge.

Comparative Uteri - Mare

• Mare uteruses are T-shaped.
• Large uterine body is ~ 20cm long.
• Uterine horns are ~ 25cm long each.
• Semen is deposited into the uterus.

Comparative Uteri - Cow

• Uterine body is short.
• Dorsal and ventral intercornual ligaments support the horns.
• Endometrium has small longitudinal and circular folds.
• Caruncles are arranged in rows and are placental attachment sites.
• Possible diapedesis of RBCs from caruncles at the end of oestrus, causing blood-tinged vaginal mucus (metoestral bleeding).
• The Cervical mucosa has many goblet-like cells
• Oestrus cases clear mucous, and pregnancy causes a thick mucous plug.

Comparative Uteri - Sow

• Uterine horns are very long at 1-2m.
• The uterine body is short.
• Fetuses are not palpable on rectal exam.
• Embryos are spaced via contractions of the myometrium.
• The sphincter between body and horns regulates the passage of piglets at farrowing.
• The Cervix is very long in sows; up to 25cm, with no fornix and high folded.
• Cervical mucosa has many goblet-like cells
• • Oestrus cases clear mucous, and pregnancy causes a thick mucous plug.
• The sow Cervix is palpable on rectal examination.
• Dieostrus and anoestrus are hard and distinct.
• In Large & oedematous oestrus & farrowing.
• The Appearance of the external ostium changes during the oestrous cycle.
• Relaxed, congested, hyperaemic during Oestrus and Farrowing.
• Contracted, shrunken & pale.
• Semen is directly deposited into the cervix by boars.