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Anatomy and Histology of Skin: Structure and Function of the Epidermis and Dermis, Exams of Pathology

An in-depth exploration of the structure and function of the skin, focusing on the epidermis and dermis layers. The composition, cellular makeup, and functions of each layer, as well as the presence of various glands and structures within the dermis. Students of anatomy, physiology, or healthcare-related fields may find this document useful for understanding the intricacies of skin histology.

What you will learn

  • What structures and glands are found within the dermis, and what functions do they serve?
  • What is the role of melanocytes in the epidermis, and how do they produce melanin?
  • What are the five layers or strata of the epidermis, and what functions do they serve?

Typology: Exams

2021/2022

Uploaded on 09/12/2022

marylen
marylen 🇺🇸

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ATLAS OF HEAD AND NECK PATHOLOGY SKIN
table of contents previous next
SKIN
Skin is composed of two layers, the epidermis, the outer layer, which is derived
from ectoderm, and the dermis, derived from mesoderm. The two layers are firmly
adherent one to another with the dermis corresponding to the lamina propria of
mucous membrane. Loose connective tissue lies under the dermis and corresponds to
the superficial fascia.
The epidermis is a stratified squamous keratinized epithelium with five layers
or strata. (1) stratum germinativum or stratum basale lies just superficial to the
dermis; (2) stratum spinosum or prickle cell layer; (3) stratum granulosum; (4)
stratum lucidum; (5) stratum corneum.
The stratum germinativum consists of a single layer of columnar or cuboidal cells.
Mitotic figures are found here which produce new cells that eventually will be dis-
placed into the next layer, the stratum spinosum, which is several layers thick and
contains cells that are scale-like or polyhedral and which become flattened toward the
surface. The name spinosum derives from “intercellular bridges” which appear to
project from one cell to another but do not indicate cytoplasmic continuity between
the cells The stratum spinosum and germinativum are grouped together as the
malpighian layer and all cells here are referred to as keratinocytes. The stratum
granulosum rests on top of the stratum spinosum and contains flattened polyhedral
cells with vesicular nuclei. These cells contain granules of keratohyalin giving a
granular appearance to the layer. The stratum lucidum is a clear translucent layer
difficult to identify in many sections. The stratum corneum is the outermost layer of
the epidermis and is composed of dead scale-like cells that become progressively
flattened and joined together. This layer stains pink and is an area for constant loss
of dead cells.
The pigment melanin is responsible for the shades of brown in the skin and is
produced by specialized cells of epidermis, the melanocytes, that are scattered among
keratinocytes of the stratum germinativum and stratum spinosum. They appear as
cells with a clear space surrounding an oval shaped nucleus and the melanin they
produce is transferred to the adjacent basal cells by phagocytosis. There is one
melanocyte for every four to ten basal cells. Melanocytes may be somewhat difficult
to identify in routine histological preparations.
The exact limits of the dermis are often difficult to identify since it merges
into the underlying subcutaneous tissue. It is composed of dense connective tissue
and itself is divided into two layers, the papillary layer, superficially, and the reticular
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SKIN

Skin is composed of two layers, the epidermis, the outer layer, which is derived from ectoderm, and the dermis, derived from mesoderm. The two layers are firmly adherent one to another with the dermis corresponding to the lamina propria of mucous membrane. Loose connective tissue lies under the dermis and corresponds to the superficial fascia.

The epidermis is a stratified squamous keratinized epithelium with five layers or strata. (1) stratum germinativum or stratum basale lies just superficial to the dermis; (2) stratum spinosum or prickle cell layer; (3) stratum granulosum; (4) stratum lucidum; (5) stratum corneum.

The stratum germinativum consists of a single layer of columnar or cuboidal cells. Mitotic figures are found here which produce new cells that eventually will be dis- placed into the next layer, the stratum spinosum, which is several layers thick and contains cells that are scale-like or polyhedral and which become flattened toward the surface. The name spinosum derives from “intercellular bridges” which appear to project from one cell to another but do not indicate cytoplasmic continuity between the cells The stratum spinosum and germinativum are grouped together as the malpighian layer and all cells here are referred to as keratinocytes. The stratum granulosum rests on top of the stratum spinosum and contains flattened polyhedral cells with vesicular nuclei. These cells contain granules of keratohyalin giving a granular appearance to the layer. The stratum lucidum is a clear translucent layer difficult to identify in many sections. The stratum corneum is the outermost layer of the epidermis and is composed of dead scale-like cells that become progressively flattened and joined together. This layer stains pink and is an area for constant loss of dead cells.

The pigment melanin is responsible for the shades of brown in the skin and is produced by specialized cells of epidermis, the melanocytes, that are scattered among keratinocytes of the stratum germinativum and stratum spinosum. They appear as cells with a clear space surrounding an oval shaped nucleus and the melanin they produce is transferred to the adjacent basal cells by phagocytosis. There is one melanocyte for every four to ten basal cells. Melanocytes may be somewhat difficult to identify in routine histological preparations.

The exact limits of the dermis are often difficult to identify since it merges into the underlying subcutaneous tissue. It is composed of dense connective tissue and itself is divided into two layers, the papillary layer, superficially, and the reticular

layer, deep. The papillary layer includes the ridges and papillae that protrude upward into the base of the epidermis and is a thin collagenous and elastic section of the dermis. The reticular layer of the dermis is the fibrous bed of the dermis with coarse, interlacing, collagenous fibers and numerous elastic fibers. Also found in the dermis, chiefly in the reticular layer, are sweat glands, hair follicles with the arrector pili muscle, sebaceous glands, ceruminal glands, and blood vessels, nerves, and lymphat- ics.

Skin, normal histology. An undu- lating epidermis is set above the dermis(homogeneous pink staining area).”