by Daniel Laberge
Human grooming

An introduction to folds in the skin

Types of folds

Initial vertical folds

The initial folds are all vertical

Human embryo at 28 days

Human embryo at 42 days

Embryo at 28 days
Embryo at 42 days

© Carnegie Collection Embryo No.6473

© Carnegie Collection Embryo No.8098

You can observe the central vertical division. It will later lead to the formation of the vertical center fold.

Usage folds - Temporary and permanent

Newborn hand

© Jason Pratt

The horizontal folds on this baby's fingers started forming several weeks before birth.

A six-week-old human embryo can arch its back and neck. By seven weeks, movement in the arms and legs can be detected by ultrasound.

Wikipedia

Permanent folds and body movements

Permanent folds on the wrist

Permanent folds on the wrist

Permanent fold formation

Permanent fold formation

Coats of fresh epidermis cells hold the fold in place and prevent any damage to the skin.

Wrinkles

Coats of epidermis cells hold the fold

The coats of epidermis cells that hold the fold in place are produced slowly over time.

We all have similar folds

Similar folds on everyone

Differences

Fold complexity

Why are the folds so hard to see?

1• The skin's wound healing process paves over them

2• All you see are the seams

Seam seen from outside and inside

Seam on a coat

seen from

outside

Same seam

seen from

inside

3• It's all epidermis

Newborn hand
Permanent fold formation