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Pl. XI · Cervix

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Pl. XI · FAM. RECIPIENTIDAE

Recipiens transiens

The Borderline  ·  cervix

The plate

The specimen, drawn

Pl. XI

Hand-drawn field-guide plate headed Recipiens transiens, var. balanus — The Borderline, Pl. XI, FAM. RECIPIENTIDAE. A rock face crossed by one sharp horizontal ink line. Above the line, dozens of chalky acorn barnacles — small volcano shapes of overlapping wall plates with a crosshatched four-plate door in the middle of each — crowded densely just above the line and thinning upward. Below the line, bare hatched wet rock with not a single barnacle on it. Below, a pink schematic of the cervical transformation zone: on the left a tall mucous simple columnar lining with a branching gland dipping below it, on the right a stratified squamous lining many cells deep with nuclei flattening toward the surface, the two meeting at a single heavy vertical line with no gradient between them, and the basement membrane running straight on underneath both. A circular inset at ×200 shows the junction enlarged.

The rock at low tide, with the transformation zone below it and the junction read at ×200 in the circle.

Habitat & range

Where it lives

Body map

Body map: a female human figure drawn as a broken pencil outline with diagonal hatching inside it, on a transparent ground. Numbered cream markers outlined in rust mark the cervix, the neck of the uterus, opening into the vagina. Below the figure, a heading reading "where it lives" and a numbered key naming each marker.

The neck of the uterus, opening into the vagina.

Range

  • The lower third of the uterus, projecting into the vault of the vagina.
  • About 2.5 cm long, with a narrow canal running through it between the internal and external os.
  • The canal is lined by mucus-secreting simple columnar; the part facing the vagina by stratified squamous.
  • Where those two linings meet is the transformation zone, and its position shifts with age and hormonal state.

Collection record

  • Add your slide numbers here.

Niche

What it does for a living

Be a door. Mucus-plugged and hostile for most of the month, thin and passable for a few days around ovulation, and tough enough below to survive being a passage.

field collected specimen

How to know it on sight

  • Two completely different linings meeting at a line, with no gradient between them.
  • On the canal side, tall pale mucus-secreting simple columnar, often with branching crypts dipping into the stroma.
  • On the vaginal side, non-keratinised stratified squamous many cells deep, nuclei flattening toward the surface.
  • The basement membrane runs straight on underneath both. The epithelium changes; the membrane does not.
Cervix histology, Masson's trichrome stain showing glands and stroma.

Specimen 1

Histological slide of the cervix tissue. Red blood cells spread across the surface with cuboidal epithelial cells. The tissue structure is composed of cells stained in red and connective tissues in blue, visualized under high magnification.

The cervix at higher power — the lining and the stroma beneath it, with blood and surface cells.

Specimen 2

Histological section of cervical stratified squamous epithelium, stained with H&E, is oriented diagonally across the frame. The well-defined squamous cells with visible nuclei layers toward the upper left, transition into disorganized inflammatory cells with amorphous purple deposits with a light pink background on the lower right. Overall frame: Light pink and dark purple cells with a white upper left and bottom right background.

Cervical stratified squamous at high power. Well-ordered layers above, flattening as they approach the surface.

Specimen 3

Microscopic image of transitional epithelium, stretched. The layered tissue section shows a stratified cellular structure, with visible cell nuclei stained purple-blue and cytoplasm in pink-red hues with a light background space. Cell morphology in this image demonstrates the transitional epithelium's unique ability to stretch

Transitional epithelium, for contrast: another multi-layered lining that is not squamous and belongs elsewhere.

Hand-drawn teaching figure in coloured pencil, pink tissue with plum nuclei on cream: five linings drawn flat in a row, each labelled — germinal stratified for the gonads; pseudostratified with long stereocilia for the epididymis and ductus; ciliated simple columnar with peg cells for the uterine tube; secretory simple columnar for the cervix and endometrium; and stratified squamous for the vagina and ectocervix.

People keep calling her by the wrong name

Look-alikes

Two plates. The first is the lining below the line on its own, which is what you will see if your section misses the junction. The second is the organ above, which shares the columnar lining but cycles and sheds, and this one does neither.

Vagina / ectocervix

Histological section of cervical stratified squamous epithelium, stained with H&E, is oriented diagonally across the frame. The well-defined squamous cells with visible nuclei layers toward the upper left, transition into disorganized inflammatory cells with amorphous purple deposits with a light pink background on the lower right. Overall frame: Light pink and dark purple cells with a white upper left and bottom right background.
Stratified squamous alone — the section missed the line.

Many layers, flattening toward the surface, no glands and no columnar anywhere. A section this uniform has missed the zone.

Uterus

A high-magnification photomicrograph reveals a human uterus in the proliferative stage. The dominant colors are red and white. The endometrium comprises a rich, red blood vessel network interspersed with endometrial glands (white hollow structures). The image suggests dense cellularity and a complex architectural arrangement of the uterine tissue.
Endometrium — columnar, but with a functional layer.

Simple columnar again, but making tubular glands in a layer that will be shed. The cervix has crypts and sheds nothing.

Examine it yourself

The virtual slide

Zoom to ×40 and run along the surface until the epithelium changes. Stop on the change itself: that single line, with the basement membrane running on underneath it, is the whole plate.

Virtual slide courtesy of Histology Guide.

YOur missions

Field Notes for Future Missions

Mission 1: find the line

Mission 2: quick check

Field notes

Why this organism

Walk a rocky shore at low tide and the barnacles stop in a line you could draw with a ruler. Above it they desiccate; below it they are eaten. The line is not a wall, it is where two different sets of rules meet, and it is the most biologically interesting place on the rock. The cervical transformation zone is that line, drawn inside a person: columnar above, squamous below, and the join is where cells get confused and where every screening test aims.

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Ordo Generativa

the makers · the whole volume.

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In the wild  ·  photograph to come.

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← Epithelial Tissues: A Guided Journey

All plates — The Tissue Field Guide: Epithelium

Frontispiece Ordo Epithelia (main page)
Pl. I · Simple squamous
Pl. II · Simple cuboidal
Pl. III · Simple columnar
Pl. IV · Stratified squamous
Pl. V · Stratified cuboidal
Pl. VI · Stratified columnar
Pl. VII · Transitional
Pl. VIII · Pseudostratified columnar
Epithelial Identification Game

All Modules
  1. Anatomical Language, Membranes & Homeostasis
  2. Just Enough Chemistry
  3. The Cell & Its Transport
  4. Making Cells & Proteins
  5. The Integumentary System
  6. The Skeletal System
  7. The Muscular System
  8. Nervous Tissue & the Senses
  9. The Spinal Cord
  10. The Brain & the Blood–Brain Barrier
  11. The Autonomic Nervous System
  12. The Special Senses
  13. The Endocrine System
  14. Blood
  15. The Heart
  16. Blood Vessels
  17. The Digestive System
  18. The Respiratory System
  19. The Urinary System
  20. Fluids, Electrolytes & Acid–Base Balance
  21. The Reproductive System
  22. The Immune System

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