BGDA Practical - Female Reproductive Tract Histology

From Embryology

Introduction

Adult human ovary peritoneal surface (viewed by endoscopy)
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This current page provides background support information for Medicine phase 1 BGD Histology Practical Virtual Slides. Page does not form part of the BGDA practical class virtual slides.



Moodle icon2.jpg Moodle Lab Slides - Female Reproductive Tract

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Slides: Female | Male | Placenta

Objectives

  1. Gain an overview of the microanatomy of the female reproductive system.
  2. Undertake a microscopical examination of the ovary, oviduct, uterus, cervix, vagina and mammary glands. The functional significance of the various histological structures identified will be discussed.

Ovary

The external surface of the ovary has a cuboidal epithelium (germinal epithelium) overlying a dense connective tissue layer (tunica albuginea). The outer epithelium is continuous with the peritoneum (serosa) forming a peritoneal fold (mesovarium) between the anterior border of the ovary with the posterior layer of the broad ligament of the uterus.

Ovary structure (regions)

  • cortex - cellular connective tissue containing the developing follicles.
  • medulla - loose connective tissue containing blood vessels, lymphatics and nerves.

Ovarian Follicle

Beginning at puberty, the ovarian primordial follicle goes through a number of developmental stages leading to the release of an oocyte at ovulation at about the middle of the menstrual cycle.

Primordial Follicle

  • located in the cortex just beneath tunica albuginea.
  • One layer of flattened follicular cells surround the oocyte (about 30 µm in diameter).
  • nucleus of the oocyte is positioned eccentric in the cell. It appears very light and contains a prominent nucleolus.
  • most organelles of the oocyte aggregate in the centre of the cell, where they form the vitelline body.

Primary Follicle

(preantral)

  • first morphological stage that marks the onset of follicular maturation
  • previously flattened cell surrounding the oocyte now form a cuboidal or columnar epithelium surrounding the oocyte.
    • cytoplasm has a granular appearance, reason also called granulosa cells.
  • continued proliferation of these cells will result in the formation of a stratified epithelium (with a distinct basement membrane) surrounding the oocyte.
  • zona pellucida becomes visible.
    • extracellular matrix formed by glycoproteins between interdigitating processes of oocyte and granulosa cells.
  • parenchymal cells of the ovary surrounding the growing follicle become organised in concentric sheaths, the theca folliculi.
Ovary follicle 01.jpg

Secondary Follicle

(antral)

  • small fluid-filled spaces become visible between the granulosa cells as the follicle reaches a diameter of about 400 µm.
  • spaces enlarge and fuse to form the follicular antrum
    • defining feature of the secondary follicle.
  • oocyte is now located on one wall of the follicle in the cumulus oophorus.
  • theca folliculi differentiates to form 2 layers the theca interna and a theca externa
    • theca interna - spindle-shaped or polyhedral cells start to produce estrogens (also increased vascularization).
    • theca externa - highly cellular connective tissue with smooth muscle cells.
  • oocyte of the secondary follicle reaches a diameter of about 125 µm.
  • follicle itself reaches a diameter of about 10-15 mm.

Preovulatory Follicle

(Graafian, tertiary, mature follicle)

  • increases further in size (in particular in the last 12h before ovulation).
  • stigma (macula pellucida) ovarian surface swelling formed by enlarging follicle.
    • thinning of the capsule, progressive restriction of the blood flow.
  • prior to ovulation the cumulus oophorus separates from the follicular wall.
  • oocyte floats freely in the follicular antrum, follicular fluid.
    • still surrounded by granulosa cells which form the corona radiata.
  • Ovulation - follicle ruptures at the stigma, oocyte, supporting cells and follicular fluid released from the ovary.
Ova20he.jpg

Corpus Luteum

  • Cells work together in the production of ovarian hormones that support the initial pregnancy.
  • Initial growth of the corpus luteum requires leutenizing hormone ( LH) from the adenohypophysis.
  • Later growth of the corpus luteum requires human chorionic gonadotrophin (hCG) from the implanting conceptus (trophoblast cells).
  • Progesterone is synthesized from cholesterol by both the large and small luteal cells upon luteal maturation.

Theca Lutein Cells

  • the darker stained cells.
  • derived from the theca interna of the original follicle.
  • lack microvilli on the surface.
  • lack the aromatase enzyme.
  • produce androgens for the granulosa lutein cells to convert.

Granulosa Lutein Cells

  • the lighter stained cells.
  • derived from the granulosa cells of the original follicle.
  • contain aromatase enzyme.
  • produce estrogen and progesterone from the androgens produced by the theca lutein cells.
Corpus Luteum Links: anatomy overview | histology overview | low power label | high power label | low power | high power | corpus albicans | theca and granulosa lutein cells | Granulosa cell | Ovary Development | Menstrual Cycle
Corpus luteum lutein cells.jpg

Corpus Albicans

corpus albicans

Hormone secretion in the corpus luteum ceases within 14 days after ovulation if the oocyte is not fertilised. In this case, the corpus luteum degenerates into a corpus albicans - whitish scar tissue within the ovaries.


Ovary Histology


Uterine Tube

(oviduct, Fallopian tube)

  • uterine tube acts as a conduit for the oocyte, from the ovaries to the uterus.
  • consists of a mucosa and a muscularis.
  • peritoneal surface of the oviduct is lined by a serosa and subjacent connective tissue.
Overview Mucosa
Uterine tube histology 02.jpg Uterine tube histology 03.jpg

Muscularis

  • inner circular muscle layer and an outer longitudinal layer.
  • inner longitudinal layer is present in the isthmus and the intramural part.
  • peristaltic muscle action for the transport of spermatozoa and oocyte.

Mucosa

  • ciliated and secretory epithelium resting on a cellular lamina propria.
  • number of ciliated cells and secretory cells varies along the tube.
  • secretory activity varies during the menstrual cycle, and resting secretory cells are also referred to as peg-cells. Some of the secreted substances are thought to nourish the oocyte and the very early embryo.

Tube Regions

Week1 001 icon.jpg
infundibulum ampulla isthmus intramural
funnel-shaped (up to 10 mm in diameter) end of the oviduct. Finger-like extensions of its margins, the fimbriae, are closely applied to the ovary. Ciliated cells are frequent. mucosal folds, or plicae, and secondary folds which arise from the plicae divide the lumen of the ampulla into a very complex shape. Fertilization usually takes place in the ampulla. narrowest portion (2-3 mm in diameter) of the tube located in the peritoneal cavity. Mucosal folds are less complex and the muscularis is thick. An inner, longitudinal layer of muscle is present in the isthmus. penetrates the wall of the uterus. The mucosa is smooth, and the inner diameter of the duct is very small.

Uterus

  • parts - body (upper two-thirds) and cervix.
  • walls - mucosal layer, the endometrium, and a fibromuscular layer, the myometrium.
  • peritoneal surface of the uterus is covered by a serosa.

Myometrium

  • smooth muscle fibres form several layers with preferred orientations.
  • muscular tissue hypertrophies during pregnancy.
  • GAP-junctions between cells become more frequent.

Endometrium

  • simple columnar epithelium (ciliated cells and secretory cells) and an underlying thick connective tissue stroma.
  • mucosa is invaginated to form many simple tubular uterine glands.
    • glands extend through the entire thickness of the stroma.
  • stromal cells of the endometrium are embedded in a network of reticular fibres.

Menstrual cycle

  • hormones alter the endometrium.
  • only the uterus body mucosa takes part in the menstrual cycle.
  • endometrial layers (based on changes)
  1. basalis - remains during menstruation, functions as a regenerative zone for the functionalis.
  2. functionalis - lost during menstruation, functions as the site of cyclic changes in the endometrium.
Uterus Histology Links: Labeled - proliferative phase | Labeled - gland proliferative phase | Labeled - secretory phase | Unlabeled - secretory phase | Unlabeled - late secretory phase | Labeled - gland secretory phase | Menstrual Cycle | Uterine Gland | Uterus Development


Links: Menstrual Cycle - Histology


Vagina

The wall of the vagina fibromuscular tube consists of 3 layers:
  1. mucosa
  2. muscularis
  3. adventitia


Mucosa

  • stratified squamous epithelium
    • deep stratum basalis, intermediate stratum spinosum, superficial layers of flat eosinophilic cells
    • rests on a cellular lamina propria (many leukocytes).
  • towards the muscularis some vascular cavernous spaces may be seen (erectile tissue).


Muscularis

  • inner circular and outer longitudinal layers of smooth muscle
  • bulbospongiosus muscle - (striated) forms an inferior sphincter around the vagina


Adventitia

  • adventitia bordering the muscularis is fairly dense and contains many elastic fibres.
  • outer part of the adventitia loose connective tissue with a prominent venous plexus.
Vagina histology 01.jpg

Mammary Gland

Adult female mammary anatomy cartoon

The mammary glands are modified glands of the skin and their development is similar to that of sweat glands.

  • compound branched alveolar glands, secretory unit is the alveolus
  • consist of 15-25 lobes separated by dense interlobar connective tissue and fat.
  • each lobe contains an individual gland.
  • lactiferous duct - excretory duct of each lobe with own opening on the nipple.

Alveolus

  • inner layer of cuboidal secretory epithelial cells
    • merocrine secretion, protein micelles are release by exocytosis.
  • outer layer of myoepithelial cells
    • located between the secretory cells and the surrounding basal lamina.
    • contraction helps force the milk from the secretory alveoli into the ducts.

Note - plasma cells in the stroma also secrete antibodies (dimeric IgA) and released into the milk, to provides passive immunity to the suckling young.

lactiferous duct lactating mammary gland
Lactiferous duct 01.jpg Mammary gland 01.jpg
Links: Mammary Gland Development | Milk

Terms

  • corona radiata - layer of cells of cumulus oophorus remaining attached to zona pellucida of oocyte after ovulation.
  • corpus - (Latin, corpus = body).
  • corpus albicans - (Latin, corpus = body + albicans = "whitish") a degenerating corpus luteum in the ovary.
  • corpus luteum - (Latin, corpus = body + luteum = yellow) major endocrine organ which is the remains of ovarian follicle after ovulation; yellow in ovary of cow where de Graaf (q.v.) first saw it.
  • cortex - (Latin = rind, or bark) outer layer of an organ.
  • cumulus oophorus - (Latin = cumulus = a little mound + Greek oon = egg + phorus = bearing) part of the wall of an ovarian follicle surrounding and carrying the oocyte.
  • fimbria - (Latin, fimbria = a fringe) the fringed open ovarian end of the uterine tube.
  • follicle - (Latin, folliculus = little bag).
  • hilum - or hilus (Latin,= a trifle; depression in a seed) a depression at vascular entrance/exit of a gland or organ.
  • mesovarium - short peritoneal fold connecting the anterior border of the ovary with the posterior layer of the broad ligament of the uterus.
  • medulla - (Latin, medulla = pith, marrow) the inner portion of an organ, in contrast to cortex.
  • menstrual - (Latin, menstruus = monthly) relating to the monthly female sexual cycle.
  • mucosa - (Latin, = mucous membrane) thin layer which lines body cavities and passages formed by epithelium and lamina propria.
  • oocyte - (Greek, öon = egg + kytos = hollow vessel (cell) the female germ cell in the ovary.
  • parenchyma - (Greek," + enkeim = to pour in) the essential functional cells of an organ as opposed to its stroma.
  • salpinx - (Greek, = a trumpet) the uterine tube.
  • serosa - (Latin, serum = whey; a pale fluid) a serous membrane lining body cavities.
  • stroma - (Greek, = a cover, table-cloth, bedding) term for the internal supporting frame-work of a tissue, or organ, as opposed to its parenchyma.
  • tunica albuginea - a dense, white, fibrous sheath enclosing a part or organ.
  • uterine tube - (oviduct, Fallopian tube)
  • uterus - (Latin, = womb, from uter = a large goatskin bag used as a wine-skin).
  • zona pellucida - (Latin, zona = a girdle + perlucere = to shine through) the refractile layer of glycoclayx (ECM) surrounding oocyte in a growing ovarian follicle.

Links: Female | Ovary | Oocyte | Uterus | Vagina


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Cite this page: Hill, M.A. 2017 Embryology BGDA Practical - Female Reproductive Tract Histology. Retrieved August 18, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/BGDA_Practical_-_Female_Reproductive_Tract_Histology

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© Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G