Female Genital System Anatomy

Female Genital System

• The female genital system is studied in the Gynecology Cytology module.
• The female genital system encompasses the ovaries, genital tract (fallopian tubes, uterus, and vagina, plus external genitalia), and mammary glands.
• The primary purpose of the female genital system is to facilitate reproduction, under hormonal, nervous, and psychological factors.

Anatomy of Genital Organs (I)

• Ovaries are located on either side of the uterus described to have an almond shape.
• At reproductive age, the average dimensions are 4 x 2.5 x 1.5 cm, altering in weight and size depending on age.
• Internally, ovaries are divided into the cortex and medulla.
• The cortex contains follicles including female gametes at differed stages of development.
• The ovarian artery (aorta branch), and the uterine artery's ovarian branches provide vascularization.
• Three layers compose the genital tract (tubes, uterus and vagina):
  • Smooth muscle wall
  • An internal mucous layer
  • Cyclical changes influenced by ovarian hormones
• The fallopian tubes guide eggs from the ovary surface into the uterine cavity, being the location of fecundation.
• Fallopian tubes are divided in:
  • Infundibulum
  • Ampulla
  • Isthmus
  • Intramural portion.
• A muscular layer coats the mucosa consisting of three types of cells:
  • Ciliated columnar cells
  • Non-ciliated
  • Intercalated cells

Embryonic Development

• The urogenital ridge and Müller's duct are crucial for understanding female genital tumors and the genesis of the ovaries.
• Formation the fallopian tubes, uterus, and the vagina's superior portion happen in the Müller's duct.
• The ovaries' coating epithelium is generated from the mesothelium.
• The similar benign and malignant lesions on the peritoneum with the ovaries, and the resemblance across the genital tract, are described to stem from this link between mesothelium and Müllerian epithelium.

Anatomy of Genital Organs (II)

• The uterus divides in three regions:
  • Body
  • Lower uterine segment
  • Cervix.
• The nulliparous uterus averages 50 grams, increasing after childbirth and decreasing following menopause, averaging from 7 to 8 cm in diameter.
• The uterus has three layers:
  • A thick muscular layer (myometrium)
  • External serosa
  • An inner mucous layer (endometrium).
• The endometrial mucosa is affected by ovarian hormone variations during the menstrual cycle.
• The endocervix meets the endometrial cavity at the less developed muscular inferior uterine segment (or isthmus), which helps with dilation during delivery

Cervix and Vagina traits

• Exocervix is lined with non-keratinized stratified squamous.
• The outside cervical orifice connects to the endocervical canal, which is lined with mucosecreting epithelium and leads to the isthmus.
• The vagina comprises of a mucous membrane and muscular layer, and it collapses in a relaxed mood to block the light.
• The external genitals involves major and minor lips, the clitoris, and the vestibule, which create a variety of glandular holes.

Anatomy of Genital Organs (III)

• Modified sweat glands known as the mammary glands emerge from mammary crests or milk lines(epidermis thickenings) that appear on human embryos.
• The persistence of certain milk line segments results in ectopic mammary tissue, commonly found in the axillary region or vulva.
• The pituitary and ovarian female glands develop after puberty, therefore, breasts experience hormonal changes and menstrual cycles until menopause, where they involute.
• The breasts are covered in skin and subcutaneous tissue and rest on the pectoral muscle, separated by the pectoral fascia.
• Breasts are structured by the terminal ductolobular unit (portion responsable for glándula) and gland ducts system.
• Each breast counts with around 15 to 20 ductal major systems, while each terminal duct is connected to sub and segmented ducts through a lactiferous sinus.

Menstrual Cycle

• The endometrium lining is shed during menstruation if fertilization happens
• The uterine corpus has two things:
  • The myometrium
  • The endometrium.
• The menstrual cycle depends on the ovarian cycle, consisting stages and sub phases, which alter endometrial composition.
• Includes follicular, lutea, and lutea degeneration. –The endometrial lining develops with glands and dense stroma, divided into basal and functional layers, undergoing menstrual changes.
• Glands and stroma endometrial changes dictate menstrual cycle stage, used to asses hormone composition

Phases of the Menstrual Cycle

• Proliferative phase, driven by estrogens produced, marked by gland proliferate
• Secretory phase: sustained by corpus luteum produced progesterone.
• The endometrium generates a high vascularized tissue, being rich in glycogen
• Glycogen accumulates underneath the cell cores, marking histologically ovulation

Endometrial stroma traits

• Spiral arteries, which have a relevant role
• Drop of estrogen and progesterone occurs in luteo lysis
• Ischemia causes degeneration of the functional layer
• Excretion by menses

Ectocervix and Endocervix

• The uterine cervix divides in two:
  • Exocervix is wrapped in stratified squamous epithelium.
  • Endocervix is composed of secreting glands to produce mucosa.
• The squamocolumnar junction is the meeting spot for these two sections, varying in position because of anatomy
• Estrogen acts on this union by favoring squamous epithelium maturation.
• Ectropion is the presence of glandular epithelium in the exocervix
• Metaplasia happens as its followed by squamous epithelium switch.
• The cervical neoplastic pathology vulnerables the location of the transformation

Follicles traits

• Made up with the oocyte and the layer of epithelial cells.
• Follicles are made of an oocyte, plus a layer of epithelial cells, who multiply and form the granulosa layer that creates estrogen.
• They transform the surrounding theca cells into external and internas, being the last one an estrogenic secretion

Pituitary and Ovarian Hormones

• Puberty triggers Gn-RH secretion, stimulating secretion of FSH(follicle stimulant)
• FSH stimulates the follicular maturation increasing levels of estrogen and a great freeing of LH coinciding with ovulation.
• Rest of follicle transform in the yellos corpus luteum, after releasing the oocyte, and secreting progesterone under LH stimulus.
• These secretion, then the estrogen and progesterone stop releasing, causing uterine mucosa to break down in menstruation
• The levels drop actives the FSH secretion

Puberty and Climacterium

• Puberty in women causes the start of menstruation, resulting in changes and functions with different effects on genital organs (breasts, uterus, vagina, genitals etc)

Hormone activity and Physiological changes on Menopause

• Mammary glands contains sparse ducts embedded in connective tissue
• Cyclic production of estrogen causes the ducts to elongate, condense connective tissue, deposit adipose, and cause the breasts growth during puberty.
• Cyclical exposure to progesterone produces secretory portion growth.
• Breast maturation occurs during puberty, and undergoes terminal differentiation while on pregnancy.

Pregnancy traits

• There is a cyclic exposition to progesterone while on ovulation, wich causes mammary grows
• The menstruation results in stromal edema reduction
• As estrogen levels drop during menopause causes the gland to atrophy
• The uterus determines endometrial atrophy
• The endometrium reduces lamina propia populated by glands.

Pregnancy and Lactation

• During pregnancy cervical mucus densifies and becomes rich in leukocytes as a defensive plug for the cervix.
• The product when the oocyte has been fertilizated on the fallopian happens to form a zygote, which descends and multiplies to turn in an uterus cavity that produces placental development.
• The placental growth inhibits the menstruation, while secreting chorionic gonadotropin hormone to product progesterona, that sustains the corpus luteum while supporting the body.
• The placenta forms with elements joining the fetus, while containing vellisties to exchange maternal/fetal blood.

Lactation traits

• Pregnancy only creates complete functionality in the mothers breasts
• Mammary glands are mosty lobes
• Estrogen and progesterone restrain milk secretion while the mammarys develop -Prolactina stimulates the glands to release milk a day before birth, while epithelial cells start releasing colostrum at first.
• The mother milk grants nutrition and provides protection for autoimmune diseases.

Anticonception traits

• Hormonal anticonceptives inhibits gestagens creating situations by which is not able perform ovulation.
• Cytological alterations may need the hormonal knowledge to be detected
• Hormonal birth controls reduces epitelial rate maturity of the cervix while causing breast mild hypertrophy.

Intrauterine Device traits (IUD)

• Hinders fertilization while preventing zygote implantation
• The hormone reinforce the device by acting over the cervix for creating mucus consistency
• Risk may incur on ectopic diseases.
• Cytology changes might indicate adenocarcinoma because of irritation.