Female reproductive histo

• Ovaries

  Almond-shaped bodies approximately 3-cm long, 1.5-cm wide, and 1-cm thick
• Ovary structure


  • Covered by a simple cuboidal epithelium, the surface (or germinal) epithelium, continuous with the mesothelium and overlying a layer of dense connective tissue capsule, the tunica albuginea
  • Most of the ovary consists of the cortex, a region with a stroma of highly cellular connective tissue and many ovarian follicles
  • The medulla contains loose connective tissue and blood vessels entering the organ through the hilum from mesenteries suspending the ovary
• Early development of the ovary


  1. Primordial germ cells migrate from the yolk sac to the gonadal primordia

  2. Cells divide and differentiate as oogonia

  3. Oogonia begin to enter the prophase of the first meiotic division but arrest after completing synapsis and recombination, becoming primary oocytes

  4. Primary oocytes become surrounded by flattened support cells called follicular cells to form an ovarian follicle
• By the seventh month of development, most oogonia have transformed into primary oocytes within follicles
• Many primary oocytes are lost through a slow, continuous degenerative process called atresia
• At puberty the ovaries contain about 300,000 oocytes
• Generally only one oocyte resumes meiosis with ovulation during each menstrual cycle and the reproductive life of a woman lasts about 30 to 40 years, only about 450 oocytes are liberated from ovaries by ovulation
• Ovarian follicle

  Consists of an oocyte surrounded by one or more layers of epithelial cells within a basal lamina
• Primordial follicle


  • Consists of a primary oocyte enveloped by a single layer of flattened follicular cells
  • Oocyte is spherical and about 25 μm in diameter, with a large nucleus containing chromosomes in the first meiotic prophase
  • Organelles tend to be concentrated near the nucleus and include numerous mitochondria, several Golgi complexes, and extensive RER
  • Basal lamina surrounds the follicular cells, marking a clear boundary between the follicle and the vascularized stroma
• Follicular growth and development

  1. Prompted by FSH, an oocyte grows most rapidly during the first part of follicular development, reaching a diameter of about 120 μm

  2. Oocyte differentiation includes growth of the cell and nuclear enlargement, mitochondria becoming more numerous and uniformly distributed, RER becoming much more extensive and Golgi complexes enlarging and moving peripherally, and formation of specialized secretory granules called cortical granules

  3. Follicular cells undergo mitosis and form a simple cuboidal epithelium around the growing oocyte, becoming a unilaminar primary follicle

  4. Follicular cells continue to proliferate, forming a stratified follicular epithelium, the granulosa, in a multilaminar primary follicle

  5. Between the oocyte and the first layer of granulosa cells, the zona pellucida accumulates, containing four glycoproteins secreted by the oocyte

  6. Stromal cells immediately outside each growing primary follicle differentiate to form the follicular theca, which subsequently differentiates further into the theca interna and theca externa
• Antrum

  Small spaces that appear between the granulosa layers as the cells secrete follicular fluid, which accumulates and gradually coalesces, producing the antrum in secondary or antral follicles
• Graafian follicle

  The mature follicle with a single large antrum that rapidly accumulates more follicular fluid and expands to a diameter of 2 cm or more
• Follicular atresia


  1. Most ovarian follicles undergo the degenerative process of atresia, in which follicular cells and oocytes die and are disposed of by phagocytic cells

  2. Atresia involves apoptosis and detachment of the granulosa cells, autolysis of the oocyte, and collapse of the zona pellucida

  3. Macrophages invade the degenerating follicle and phagocytose the apoptotic material and other debris
• Follicular atresia is most prominent just after birth, when levels of maternal hormones decline rapidly, and during both puberty and pregnancy, when qualitative and quantitative hormonal changes occur again
• During a typical menstrual cycle, one follicle becomes dominant and develops farther than the others, usually reaching the most developed stage and undergoing ovulation, while the other primary and antral follicles undergo atresia
• Follicular atresia

  1. Apoptosis and detachment of granulosa cells

  2. Autolysis of oocyte

  3. Collapse of zona pellucida

  4. Macrophages invade and phagocytose apoptotic material and debris
• Follicular atresia takes place from before birth until a few years after menopause, but is most prominent just after birth, during puberty, and during pregnancy
• Follicular development and ovulation

  1. One follicle becomes dominant

  2. Dominant follicle undergoes ovulation

  3. Other follicles undergo atresia

  4. Dominant follicle produces estrogen to prepare reproductive tract
• Antral follicle


  Fluid-filled cavities or vesicles form within the granulosa layer
• Mature follicle


  • Large single antrum filled with follicular fluid
  • Oocyte projects into fluid-filled cavity surrounded by granulosa cells
• Ovulation


  • Hormone-stimulated process by which oocyte is released from ovary
  • Occurs midway through menstrual cycle
• Events around ovulation


  1. Meiosis I completed by primary oocyte

  2. Granulosa cells produce more prostaglandin and hyaluronan

  3. Ballooning and weakening of ovarian wall

  4. Smooth muscle contractions expel oocyte and fluid
• Secondary oocyte


  Haploid cell containing 23 chromosomes, arrested in metaphase II
• Corpus luteum

  Temporary endocrine gland formed from ovulated follicle
• Formation of corpus luteum

  1. Granulosa and theca interna cells reorganize

  2. Cells change histologically and functionally under LH influence

  3. Produce progesterone and estrogen
• Without pregnancy


  Corpus luteum degenerates, leading to menstruation
• With pregnancy


  Corpus luteum maintained by HCG, secretes progesterone to maintain uterine mucosa
• Corpus albicans

  Scar of dense connective tissue formed from remnants of degenerated corpus luteum
• Uterine tubes


  • Funnel-shaped infundibulum with fimbriae
  • Expanded ampulla where fertilization occurs
  • Narrow isthmus
  • Intramural portion passing through uterine wall
• Uterine tube wall


  • Folded mucosa
  • Thick muscularis with circular and longitudinal smooth muscle
  • Thin serosa
• Uterine tube epithelium


  • Contains ciliated cells that sweep fluid and sperm
  • Contains secretory cells that produce fluid to nourish sperm and oocyte
• Wall of the oviduct

  • Folded mucosa
  • Thick, well-defined muscularis with interwoven circular and longitudinal layers of smooth muscle
  • Thin serosa covered by visceral peritoneum with mesothelium
• Mucosa of the oviduct

  • Numerous branching, longitudinal folds most prominent in the ampulla
  • Folds become smaller in regions closer to the uterus and are absent in the intramural portion of the tube
• Mucosa of the oviduct

  Lined by simple columnar epithelium on a lamina propria of loose connective tissue
• Cell types in the oviduct epithelium

  • Ciliated cells
  • Secretory peg cells
• Fertilization


  1. Sperm undergo acrosomal reaction

  2. Sperm proteins bind ZP3 and ZP4 receptors, activating acrosin

  3. First sperm penetrates zona pellucida and fuses with oocyte, triggering cortical reaction

  4. Oocyte completes meiosis II

  5. Sperm and oocyte nuclei fuse to form zygote
• Uterus


  Pear-shaped organ with thick, muscular walls
• Layers of the uterine wall

  • Perimetrium (outer connective tissue layer)
  • Myometrium (thick tunic of highly vascularized smooth muscle)
  • Endometrium (mucosa lined by simple columnar epithelium)
• Myometrium


  • Bundles of smooth muscle fibers separated by connective tissue
  • Interwoven layers with fibers parallel to long axis of organ
  • Undergoes extensive growth during pregnancy, strengthening uterine wall
• Endometrium


  • Lamina propria contains nonbundled type III collagen fibers with abundant fibroblasts and ground substance
  • Simple columnar epithelial lining with ciliated and secretory cells
  • Basal layer adjacent to myometrium
  • Functional layer with spongier lamina propria