3. Apocrine Glands
Present in axillae,periumbilical region,perineal and
circumoral areas,prepuce,scrotum,mons pubis,labia
minora.
Modified apocrine glands are
External Auditory Canals(ceruminous Glands),
Eyelids(Moll’s Glands),
Mammary glands.
4. Development
Primary epithelial germ layer or hair germs in 4th – 5th
month of IUL
After 5th month,most regress and persists only in the
sites mentioned
Small and non-functional until puberty when they
enlarge and start secreting their product
5. FUNCTION
In humans is not entirely clear
Continuously secrete very small quantities of an oily
odourless sterile fluid which when modified by
cutaneous bacteria serve as pheromone in animals
May also play some role in olfactory communication
6. STRUCTURE
Coiled secretory portion
Lower part of dermis or subcutaneous
tissue
Lined by columnar or cuboidal cells
depending upon stage of secretion
Ductal portion
Empties into the infundibulum of
hair follicle slightly above the entrance of
sebaceous duct or directly on surface
7. Apocrine gland
Lumen lined by a single layer of cuboidal or columnar
cells
Pale staining cytoplasm
Round nuclei situated near the base of of the cells
Apical borders of the cells project into the lumen
Distal portion of the cells have the appearance of being
“pinched-off” or “decapitated”
9. Secretory cells are surrounded by
A layer of contractile myoepithelial cells
A PAS positive basement membrane zone
Type 3 collagen bundles and elastic fibres of the
periadnexial dermis
10. Apocrine excretory duct
2 layers of cuboidal cells
An inner periluminal cuticle
No outer myoepithelial lining
Distally the epithelium merges with the epithelium of
a hair follicle
The intrafollicular portion is straight (spiraled in
eccrine duct)
11. Ultrastuctural features
Typical of secretory epithelia
Prominent
rER,GA,ribosomes,mitochondria,lysosomes
Secretory granules near the lumen
Reactive histochemically for iron,lipofuscin,neutral
mucopolysaccharides
12. Regulation of secretion
Nervous system
Sympathetic
Cholinergic
Sudomotor transmission
Nerve endings in the close proximity release neurohormonal
transmitters that diffuse into periaadnexial capillary
networks that nourish the secretory coils
Emotional stresses
Sympathetic discharge causes myoepithelial contraction
and excretion of the secretion
13. APPLIED ASPECT
DISORDERS OF APOCRINE GLANDS
Bromhidrosis : bacterial decomposition of the secretion on skin surface
modifies it resulting in Rancid body odour(Corynebacterium spp.) and
sweaty odour(Micrococcus spp.)
Apocrine chromhidrosis – secretion of pigmented(yellow,green,black)
sweat due to Rich lipofuscin content of apocrine sweat or high state of
oxidation, mainly on face and axilla
‘Pseudochromhidrosis’ or extrinsic apocrine chromhidrosis – staining
of the sweat by chromogenic bacteria esp. Corynebacterium spp. or
garments
Apocrine miliria(Fox – Fordyce disease)
It is chronic,pruritic,papular eruption of the apocrine areas,principally
axilla and pubis. May be due to Occlusion of apocrine ducts by a
keratinous plug induced by functional hormonal changes
15. Hidradenitis Suppurativa
Syn- Apocrinitis, Acne inversa
Definition- is a chronic relapsing inflammatory
disease of apocrine gland follicles
It is follicular occlusion disorder, apocrine glands are
involved secondarily in inflammatory process
16.
17. Eccrine Units
These are true sweat gland in humans
Present almost everywhere on the human skin except
on the lips,nail beds,clitoris,labia minora and external
auditory canal
also called as atrichial since they develop from
superficial epidermis and remain independent of the
hair follicle. Eccrine are merocrine and are primarily
involved in thermoregulation.
18. Development
Embryologically these are specialized downgrowth of
epidermis independent of the folliculo sebaceous unit,
at 4th month of IUL
Descend to near the junction of dermis and
subcutaneous tissue
3 million units present at birth , no units formed
thereafter
19. Eccrine unit can be divided into
1. An irregularly coiled secretory gland(proximally)
2. A dermal duct leading from the gland
3. A spiraled intraepidermal
duct(acrosyringium)
20. Eccrine gland :
SECRETORY PORTION
2 rows of cells
A discontinuous outer row of spindle shaped,contractile
myoepithelial cells
An inner row of pyramid-shaped,secretory epithelial cells
2 types of cells
Large glycogen containing pale or clear cells(lumen)
Smaller mucopolysaccharide containing dark
cells(periphery)
22. Eccrine dermal duct
Lined by a double layer of
small,darkly
basophillic,cuboidal epithelial
cells
Each duct enters the
epidermis at the nadir of a rete
ridge and coils and widens as
it spirals upward to open
directly onto the skin surface
24. Intraepidermal keratinocytesof an eccrine duct are
accomplanied by very few melanocytes but they
contain keratohyaline granulesand are linked to one
another and to neighbouring epidermal keratinocyte
by desmosomes
Eccrine and apocrine ducts unlike their glands,are
indistinguishable from each other histologically
25. Sweating
Commences in the pale(clear) cells of the secretory
portion of the eccrine gland
Energy requirements of sweat secretion are met by the
numerous mitochondria and glycogen particles within
these cells
Intercellular canaliculi transport the solution secreted
by pale dark cells to the lumen of secretory coil
26. Secretory and myoepithelial cells of the eccrine gland
are innervated predominantly by the unmyelinated
cholinergic class C nerve fibres(sympathetic nervous
system)
Maximal rate of eccrine secretion in response to
cholinergic stimulation is 5 times that in response to
adrenergic stimuli
28. These mediators may act on contraluminal plasma membranes
of the pale cells
Increases their permeability
Allows sodium,chloride,other electrolytes to diffuse into the
cytoplasm
An energy requiring Na pump located at the canalicular plasma
membrane of pale cells then may trnsport Na actively into
canaliculi ,folld. By transportation of chloride and water
A soln of “precursor sweat” is produced that is isotonic to plasma
Aldosterone acts upon the epithelium that lines eccrine ducts
Stimulates reabsorption of sodium in partial exchange for
potassium
30. The epithelium of excretory ducts is relatively
impermeable to water
This enables ductal reabsorption of greater amounts
of sodium than of water
Excretion of a hypotonic solution known as “sweat”
Myoepithelial cells contract in response to provide
mechanical support the wall of the secretory coil as it
butresses itself against increases in luminal
hydrostatic pressure
31. Eccrine sweat
1. An odorless,colorless,hypotonic solution
2. Specific gravity : 1.005
3. pH : 4.5 – 5.5
4. Sodium- initially low (10-20 mmol) gradually increasing to reach around
100mmol.
5. Potassium- 5-6mmol.
6. Chloride- concentration increases with increase in sweat secretion.
7. pH- 7.2-7.3 and HCo3- 14mmol in primary sweat
8. Lactate- 30-40mmol
9. Solutes :
Na,Cl,K,urea,lactate,HCO3,NH3,Ca,P,lactate,Mg,SO4,Zn,Fe,iodide,amino
acids,proteins,Igs
10. With increased rates of sweating, pH increases, Na and Cl conc
increases,K,lactate and urea conc. decreases
32. Function of eccrine gland
To produce sweat during periods of stress induced by heat
Excessive body heat dissipated by evaporation of water
excreted onto the skin surface
I L of evaporated sweat removes approx. 585 kcal of heat
from the body
A temperatjure control centre in the preoptic area and
anterior nucleus of the hypothalamus serves as a neutral
thermostat that regulates the temperature of blood with
thermosensory impulses that arise in the skin
An increases inbody temperature of 0.01 degree C excites
hypothalamic stimulation of eccrine sweating via efferent
pathways of sympathetic nervous system
33. The 1st response to elevation of temperature is an
increase in the no. of eccrine glands that function
actively
With increasing thermal stress, an increased amount
of sweat is secreted by each gland
2 – 3 l of sweat produced per hour by individuals
exposed to high environmental temperature
During exercise,catecholamines secreted by adrenal
glands help tp mediate the maximisation of sweating
This is not seen in heat induced sweating
34. During prolonged stress, for eg. in tropical climates,
eccrine glands become acclamatised , i.e. they acquire
ability to secrete more copious amounts of sweat at a
greater rate in response to relatively smaller elevations
in boby temperature
At the same time adrenal cortex secretes more
aldosterone which increases the reabsorption of
sodium in swaet duct thereby preventing excessiv e
sodium loss
35. Eccrine glands of the palms,soles,axillae and forehead
respond predominantly to emotional rather than
thermal stimuli
Certain heavy metals (eg. Lead, mercury) and some
drugs (eg. Ethanol, griseofulvin)are excreted in sweat
36. Disorders of eccrine glands
Hyperhidrosis
Causes of generalised hyperhidrosis
Febrile infective illness-TB, malaria, brucellosis
Metabolic-DM, Hyperthyroidism, hypoglycaemia,
hyperpituitarism
Parkinson’s disease
Menopause
Internal malignancy and lymphomaNeurological
disorders-Familial dysautonomia,Episodic
hypothermia with hyperhidrosis
Drugs- fluoxetin
37. Palmoplantar hyperhidrosis- emotional stimuli
increases sweating of palms and soles.Sweating
may be continuos or phasic.
Complications include pompholyx, contact
dermatitis, pitted keratolysis
39. SWEAT GLAND LESIONS
Aplasia
Hypohidrotic ectodermal dysplasia
Ichthyosis
Any cause of atrophy (acro dermatitis chronica atrophicans)
Scleroderma & sjogren’s syndrome
Ross’s syndrome
Consists of wide spread hypohidrosis combined with patchy compensatory
hyperhidrosis together with tonic pupils& loss of deep tendon reflexes. The
changes are due to selective degeneration of sympathetic pathway.
Sweat retention syndromes
Miliarias
Tropical anhydrotic asthenia
Pompholyx
40. Apoeccrine gland
Present in the axillae of adults
10 to 45% of all glands in the axilla
Thought to develop during puberty from eccrine-like
precursors
Larger than typical apocrine glands
Ducts open directly onto the surface of the skin via the
epidermis
Secretory portion is irregularly dilated
Epithelial lining of the dilated segments of the gland
resembles that of the apocrine gland
Epithelial lining of the undilated segments resembles that
of the eccrine gland
41. Apoeccrine glands contribute to axillary sweating in
adults
Studies have shown that these glands secrete copious
quantities of a serous solution of sweat in response to
cholinergic and adrenergic stimulation