- Human Skin Histology.

-Human skin is considered the largest organ of the body and form  about 16% of the body weight (1) with a surface area somewhat less than 1.5 m² (2).
-The skin form the external surface of the human body.At the orifices of the mouth,nose and the anal canal, the skin join the mucous membrane at the muco-cutaneous junction (3).

-Types of human skin (1):-

1. Thick skin (Non-Hairy) which has thick epidermis and found only in the palms and soles as they are the most sites subjected to abrasions and trauma and thick skin shows characteristic parallel ridges and grooves which are called "Finger prints".
2. Thin skin (Hairy) which has thin epidermis and covers the rest of the body.
   

-Histological structure of the skin :-

skin is composed of 3 layers

1. Epidermis
2. Dermis
3. Hypodermis (Subcutaneous fatty layer) 

1- Epidermis:-

• It is the outer superficial epithelial layer of skin.
• It is composed of Stratified squamous keratinized epithelium.
• The thickness of the epidermis varies in different types of skin. It is the thinnest on the eyelids and the thickest on the palms(0.8mm) and soles(1.4mm).
• The epidermis is ectodermal in origin.
  
• The epidermis is devoid of blood vessels and gets its nutrition through diffusion.
  
  
  

- Organization of human body.

1- Human body (total organism) is complicated &

highly organized & composed of number of systems:-

-Musculoskeletal system.
-Respiratory system.
-Cardiovascular system.
-Hemic and lymphatic systems including immune system.
-Gastrointestinal system.
-Urogentital system.
-Endocrine system.
-Nervous system.
-Integumentary system:- skin, hair and nails.


2- One system is composed of group of organs which

together perform the over all function of the system.(1)

3- An organ :- is composed of several different tissues

which together perform the particular function of the organ.


4- A Tissue :- is a group of cells working together &

these cells are separated by inter-cellular substance.

e.g Muscular tissue & neural tissue.(1)


5- Cell :- is the smallest living unit of the body construction (2)&

it is the structural & functional unit in the body.

cell is composed of complex structure called protoplasm.(2)

In eukaryotes the protoplasm surrounding the cell nucleus

is known as the cytoplasm and

that inside the nucleus as the nucleoplasm.(3)


6- Protoplasm is composed of a mixture of different molecules :-

- water 70%

- proteins 15%

- nucleic acids 1%

- polysaccharides 3%

- lipids 1%

- Minerals & others 4%


7- Molecules are formed of elements :-

- carbon (C)

- hydrogen (H)

- oxygen (o)

- Nitrogen (N)

- phosphorus (p)

- sulfur (s)


Elements are substances which cannot be broken down further

by ordinary chemical means


*References:-

(1) Introduction to anatomy ,Anatomy & embryology department,
Mansoura uni 2006.
(2) Principles of histology vol 1 , Ch 2 cytoplasm,
histology staff members , Mansoura uni 2006.
(3) wikipedia here
(4) Medical biochemistry, Vol 1,Physical chemistry,
Medical biochemistry staff members,2006.

- Blood groups - ABO system.

- Many systems have been discovered to differnetiate bloog groups,the most famous system is ABO system.



- ABO system represent antigenic components on the surface of RBCs according to which
this system was made.
- O RBCS means that there is no antigens on the surface of RBCs so we can give O RBCS
to all other types of RBCs groups.

- B RBCS means that there is B antigens on the surface of RBCs so we can give B RBCS
Only to B person or AB person.

- A RBCS means that there is A antigens on the surface of RBCs so we can give A RBCS
Only to A person or AB person.

- AB RBCS means that there Are both A,B antigens on the surface of RBCs so we can give AB RBCS Only to AB person.

- Muscles.

-Types :-
There are 3 types of muscles each type of muscles has its specific structural and functional unit which is called muscle fiber ( cell):-
1- skeletal muscle has skeletal muscle fiber.
2- cardiac muscle has cardiac muscle fiber.
3- smooth muscle has smooth muscle fiber.

- Innervation of the muscles:-
*skeletal muscle fiber has somatic innervation.
* both cardiac muscle fiber and  smooth muscle fibers have autonomic innervation.
so
-skeletal muscle fiber is under voluntary control
- both cardiac muscle fiber and smooth muscle fibers are under involuntary control.

-Three in human ear.

There are...

- 3 parts of the human ear:-

1. External ear.
2. Middle ear.
3. Inner ear.

- 3 parts of the External ear:-

1. auricle (pinna).
2. external auditory meatus.
3. Tympanic membrane.

- 3 layers in tympanic membrane:-

1. Outter skin layer.
2. middle fibrous layer.
3. inner mucosal layer.

- 3 cranial nerves innervate the tympanic membrane:-

1. C.N. V (trigeminal).
2. C.N. IX(glossopharyngeal).
3. C.N. X (Vagus).

 -3 Parts of middle ear:-

1. Tympanic cavity.
2. Eustachian tube.
3. Mastoid air cells.

- 3 parts of the tympanic cavity:-

1. epi-tympanum.
2. meso-tympanum.
3. hypo-tympanum.

- 3 middle ear bones (auditory ossicles):-

1. malleus.
2. incus.
3. stapes.

- 3 parts of the malleus:-

1. Head.
2. lateral process.
3. handle.

- 3 parts of labyrinth:-

1. Bony cochlea.
2. 3 semicircular canals.
3. Vestibule.

- 3 semicircular canals :

1. Posterior.
2. lateral.
3. superior.

- 3 compartments of cavity of bony cochlea :-

1. scala vestibuli: Upper compartment.
2. scala media (cochlear duct):middle compartment.
3. scala tympani: lower compartment.

- 3 membranes in cochlear duct:-

1. vestibular.
2. Tectorial.
3. Basilar .

- 3 labyrnthine sensory end organs:-

1. Of cochlea..called organ of corti.
2. of s c c....called crista.
3. of utricle and saccule..called macula.

Enjoy it,,,,,
Dr Ibrahim...

- Anatomy and histology of eye lids.

- Eye lid :

• It is movable muco-cutaneous fold covering anterior surface of eye globe.
• Upper eye lid is more movable than lower eye lid as it have levator palpebrae superioris muscle and Muller's muscle .
• The upper eyelid skin crease (superior palpebral furrow) is approximately 8-11 mm superior to the eyelid margin and is formed by the attachment of the superficial insertion of  levator aponeurotic fibers  (8-9 mm in men and 9-11 mm in women).

-The palpebral fissure is that empty space between the upper and  lower eyelid margins when the eyelids are open (that is, the space between the eyelids that allows you to see  your eyeball and your eyeball to see the world).

- Histology of the cornea.

Histological structure :- is Composed of 5 Layers:-

1- Epithelium:-

• Active mitosis → regeneration within 6- 24 hrs.
• Continue with conjunctiva.

2-Bowman's membrane:-

• Acellular Clear membrane lie under the epithelium.
• Ends abruptly at the limbus. (i.e. end in folded manner)
• Is considered as modified lamella of stroma.
• If destroyed cannot regenerate.

3-Stroma:-

• Represent 90% of corneal thickness .
• Formed of collagen fibrils (Type 1) which has special arrangement which run parallel to each other and parallel to the surface of the cornea making the cornea transparent, unlike sclera in which arrangement is not done in specific way so appear opaque.
• Collagen fibrils lie in mucoid matrix Scattered keratocytes lie between lamellae and are stellate in shape.

4-Descemet's membrane:-

• An elastic membrane which lie ( ) Endothelium and stroma.
• It is resistant to pathology and regenerate easily. 
• This layer is continuous with material of the pectinate ligament or trabecular meshwork of the iris.

5-Endothelium:-
Single layer of flat hexagonal cells with No mitosis.

- Pumps water out → prevent corneal edema → prevent corneal opacification.

(By light microscope)

So Cornea formed of :-

• Epithelium resting on B.M
• Endothelium resting on D.M
• stroma in between

-Turner Syndrome.

Turner Syndrome

*Def :- It is a condition in which a female has only one X sex chromosome instead of XX in her cells (i.e XO or monosomy ) (1).

*Synonyms:-

• Ullrich-Turner syndrome.
• Gonadal dysgenesis (2).
  

*Pathophysiology:-
- Most commonly due to non-disjunction of chromosome X during formation of ova so ovum with one X chromosome when fertilized an by sperm carrying X chromosome give baby with XO.
- It occurs also in normal ovum when fertilized with sperm neither X nor Y .

* Although in females,only one X chromosome is active , the presence of two X chromosomes is essential for development of the ovaries (1).

*Karyotype (1) :- 45,XO

*Buccal smear:- -ve Barr's body.

*Hormonal assay:- decrease sex hormones.

* Clinical picture (1):-

• Short stature ( most common presentation).
  
• Lymphedema (swelling) of the hands and feet
• Broad chest (shield chest) and widely-spaced nipples
• Low hairline
• Low-set ears
• infertility ( due to ovarian dysgenesis)
• Amenorrhea, or the absence of a menstrual period
• Increased weight, obesity
• Shield shaped thorax of heart
• Shortened metacarpal IV (of hand)
• Small fingernails
• Characteristic facial features (e.g hypertelorism,epicanthic fold,narrow maxilla)
  
• Webbed neck from cystic hygroma in infancy.
• Congenital heart diseases in 35% of cases mainly Coarctation of the aorta.
• Poor breast development.
• Congenital renal diseases (e.g Horseshoe kidney).
• Cubitus valgus ( wide carrying angle).
  
• Mental development is subnormal "but intelligence is normal".
  

*Prognosis:-

While most of the physical findings in Turner syndrome are harmless, there can be significant medical problems associated with the syndrome.

*Treatment:-

As a chromosomal condition, there is no cure for Turner syndrome. However, much can be done to minimize the symptoms. For example:-(3)

• Growth hormone, either alone or with a low dose of androgen, will increase growth and probably final adult height. Growth hormone is approved by the U.S. Food and Drug Administration for treatment of Turner syndrome .(3)
• Estrogen replacement therapy at 14-15 years has been used since the condition was described in 1938 to promote development of secondary sexual characteristics.Estrogens are crucial for maintaining good bone integrity and tissue health (3).
  

Return to list of medical syndromes here

*References:-

(1) Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g76.

(2)James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0721629210.
(3)Turner Syndrome Society of the United States. "FAQ 6. What can be done? Retrieved 2007-05-11.

- Klinefelter's syndrome.

Klinefelter's syndrome

*Def:- It is a condition in which males have an extra X sex chromosome (i.e XXY) in his cells(1).

*Incidence:-

• The most common sex chromosome disorder (2).
• The second most common condition caused by the presence of extra chromosomes.
• Roughly it occur by 0.1% in males.
  

* Klinefelter syndrome is named after Dr. Henry Klinefelter, an endocrinologist at Massachusetts General Hospital in Boston, Massachusetts, who first described it in 1942 (3).

*Pathophysiology (1):-

• Most commonly Due to non-disjunction of chromosome X at one of the meiotic divisions so an ovum with XX chromosome when fertilized by a sperm carrying Y chromosome lead to formation of baby with XXY .
• less commonly,the condition arise when a normal ovum is fertilized by XY sperm .
• The condition may appear with XXXY or XXXXY due to non-disjunction at both meiotic divisions this will lead to more mental retardation.

*Karyotype (1) :-

• 47,XXY
• 48,XXXY
• 49,XXXXY

*Buccal smear:- +ve Barr's body.

*Hormonal assay:- decrease androgens.

*Clinical picture:-

• Infertility.
• Gynecomastia.
• Subnormal intelligence or Mental retardation.
• microorchidism (i.e. small testicles)(4).
• Absence of body hair.
• Long stature (due to absence of androgens which help closure of epiphysis).

Complications:

ü  Leg ulcers

ü  Osteoprosis

ü  Carcinoma of breast

Treatment: Testosterone (11-12y)

ü  can improve behaviour and learning.

ü  Prevent osteoporosis

ü  Development of 2ndry sexual characters

Intra-cytoplasmic sperm injection (ICSI) can help with fertility in men who produce minimal sperm.

Recurrence risk is very low.

 

Return to list of medical syndromes here

*References:-
(1) Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g75.
(2)James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. p 549. ISBN 0721629210.
(3)Klinefelter, HF Jr; Reifenstein, EC Jr & Albright (1942), "Syndrome characterized by gynecomastia, aspermatogenesis without a-Leydigism and increased excretion of follicle-stimulating hormone", J Clin Endocrinol Metab 2: 615–624. Klinefelter, HF (1986), "Klinefelter's syndrome: historical background and development", South Med J 79(45): 1089–1093 talks about the history of the development of the literature.
(4)Leask, Kathryn (October 2005). "Klinefelter syndrome" (HTML). National Library for Health, Specialist Libraries, Clinical Genetics. NationalLibrary for Health. . Retrieved 2007-04-07.

- YY syndrome.

YY syndrome

*Def :- A genetic condition where males have an extra Y chromosome (i.e XYY) in each of their cells .

* This is not usually an inherited condition but a defect that occurs during cell division.

* Often the condition is asymptomatic.

* Incidence :- rare disease.

*Synonyms:-

• Diplo-Y Syndrome.
• Polysomy Y.
• XYY Chromosome Pattern.

*Pathophysiology:-
Due to non-disjunction of chromosome Y during 2nd meiotic division so YY sperm when fertilizes an ovum carrying X chromosome give baby with XYY.

*Karyotype :-
47,XYY

* Clinical picture:-

• Tall stature
• Subnormal intelligence.
• Developmental delays.
• May show aggressive tendency or antisocial behavior.

Return to list of medical syndromes here

*References:-
- Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g75,76.

- Cri Du chat syndrome.

Cri Du chat syndrome

*Synonyms:-

• chromosome 5p deletion syndrome.
• 5p minus syndrome.
• Lejeune’s syndrome.

*Incidence:- rare.

*Pathophysiology:-
results from deletion of the distal short arm of chromosome no 5 (1).

*Karyotype :-
46,xx,5p-(female).
46,xy,5p-(male).
(5p- means that the short arm of chromosome 5 is shorter than normal).

*Clinical picture:-

• characteristic cry of affected infants, which is similar to that of cat ( i.e a high-pitched cry ) due to problems with the larynx and nervous system,about 1/3 of children lose the cry by age 2.
• feeding problems because of difficulty swallowing and sucking.
• low birth weight
• growth retardation.
• Mental retardation.
• hypotonia.
• microcephaly.
• cardiac defects (eg, ventricular septal defect [VSD],atrial septal defect [ASD], patent ductus arteriosus [PDA], tetralogy of Fallot).

*Treatment:-

• No specific treatment is available for this syndrome.
• The mental retardation must be addressed.

Return to list of medical syndromes here

*References:-
Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g74.

- Wolf-Hirschhorn Syndrome.

Wolf-Hirschhorn Syndrome

*Pathophysiology:-
results from deletion of the distal short arm of chromosome no 4 (1).

* Clinically, the minimal diagnostic criteria for Wolf-Hirschhorn syndrome (ie, ‘‘core’’ phenotype) consists of typical facial appearance , mental retardation, growth delay, hypotonia and seizures (or EEG anomalies)(2).

* Different categories of the Wolf-Hirschhorn syndrome phenotype are defined according to the extent of the chromosome.4 deletion(2):-

• 1st category :- caused by small deletion that is usually associated with a mild phenotype, lacking major malformations. This category is likely under-diagnosed.
• 2nd category :- caused by large deletions that cause the widely recognizable Wolf-Hirschhorn syndrome phenotype.
• 3rd category :- caused by very large deletions that cause a severe phenotype that can hardly be defined as typical Wolf-Hirschhorn syndrome.

* Factors affecting prognosis include (2):-

• extent of the deletion.
• occurrence of complex chromosome anomalies.
• severity of seizures.

*Karyotype (1):-
46,xx,4p-(female).
46,xy,4p-(male).
(4p- means that the short arm of chromosome 4 is shorter than normal).

* Clinical picture(3),(4):-

• Growth retardation.
• CNS:- Developmental delay and mental retardation of varying degree,microcephaly, seizures, congenital hypotonia with muscle hypotrophy particularly of the lower limbs.
• Skull:- Frontal bossing, high frontal hairline, hemangioma over forehead or glabella, scalp defect with or without underlying bony defect.
• Face:- Characteristic features including prominent glabella, hypertelorism, broad beaked nose, and frontal bossing, collectively described as "Greek warrior helmet" facies.
• Eyes:- Hypertelorism, down-slanting palpebral fissures, epicanthal folds, strabismus, coloboma, proptosis.
• Nose :- Broad or beaked nose, nasolacrimal duct stenosis or atresia
• Mouth:- Short upper lip, short philtrum, cleft lip or palate, bifid uvula, carplike mouth, micrognathia, retrognathia
• Teeth:- Hypodontia
• Ears:- Low-set ears; large, floppy, or misshapen ears; microtia; preauricular dimples; chronic otitis media with effusion; sensorineural hearing loss.
• Cardiovascular:- Atrial septal defect, ventricular septal defect.
• Pulmonary:- lung hypoplasia secondary to diaphragmatic hernia.
• GIT:- Diastasis recti, umbilical or inguinal hernias, accessory spleens, absent gallbladder, diaphragmatic hernia, intestinal malrotation.
• Genitourinary:- Hypoplastic kidneys, cystic dysplastic kidneys, unilateral renal agenesis, hydronephrosis, exstrophy of bladder, hypoplastic external genitalia.
• Skeletal:- Long slender fingers with additional flexion creases, long narrow chest, hypoplastic widely spaced nipples, hypoplasia or duplication of thumbs and great toes, hypoplasia of pubic bones.

Return to list of medical syndromes here

*References:-
(1) Principles of histology vol1,staff members ,faculty of medicine,mansoura university,ch3,p.g74.
(2) Zollino M, Murdolo M, Marangi G, et al. On the nosology and pathogenesis of
Wolf-Hirschhorn syndrome: genotype-phenotype correlation analysis of 80 patients
and literature review. Am J Med Genet C Semin Med Genet. Nov 15 2008;148C(4):257-69. [Medline].
(3)Battaglia A, Carey JC, Wright TJ. Wolf-Hirschhorn (4p-) syndrome. Adv Pediatr. 2001;48:75-113. [Medline].
(4)South ST, Whitby H, Battaglia A, Carey JC, Brothman AR. Comprehensive analysis of Wolf-Hirschhorn syndrome using array CGH indicates a high prevalence of translocations. Eur J Hum Genet. Jan 2008;16(1):45-52. [Medline]. [Full Text].

- Chromosomal anomalies (aberrations).

Chromosomal Aberrations

Def: is a deviation from the normal number (numerical aberrations) or the normal shape (morphology) of chromosomes (structural aberrations).

They are a common cause of early spontaneous miscarriage.

Incidence: is about 1 in 150; often cause multiple congenital anomalies and cognitive difficulties.

Acquired chromosomal changes play a significant role in carcinogenesis and tumour progression.