Migration of

the

Conceptus

The egg is

fertilized in the

distal end of the

uterine tube, and

the pre-embryo

begins cleavage as

it migrates to the

uterus.

Ovary

Maturing

follicle

Corpus

luteum

Ovulation

Secondary

oocyte

First polar

body

Sperm Cell

Fertilization

(0 hours)

Zona

pellucida

Sperm

pronucleus

Egg

pronucleus

Second polar

body

*Zygote

 

Cleavage

Blastomeres

2-celled stage

(30 hours)

4-celled stage

8-celled stage

Morula (72

hours)

Blastocyst

Implanted

blastocyst

(6 days)

Ectoderm

Mesoderm

Mesoderm

 

Structure of

the skin and

subcutaneous

tissue.

Dermal Papilla responsibly for exchange of oxygen, nutrients and waste products between the dermis and

the epidermis. *Provides hair with its sole source of nutrition.

Tactile Corpuscle (touch receptor nerve ending in the skin that is responsible for sensitivity to light touch. In particular, they

have highest sensitivity (lowest threshold) when sensing vibrations lower than 50 Hertz.

They are rapidly adaptive receptors.

Blood Capillaries provide oxygen and nutrients to the cells of the body and remove carbon dioxide and

waste materials.

Hair Follicle A hair follicle is a mammalian skin organ that produces hair. Hair production occurs in

phases, including growth (anagen), cessation (catagen), and rest (telogen) phases. Stem

cells are responsible for hair production.

Sebaceous gland Produce an oily secretuion called sebum. *Oil producing gland associated with hair follicles

Hair receptor Entwine each follicle and respon to hair movements

Apocrine Sweat gland Produce secretion by exocytosis. Scent glands that respond especially to stress and sexual

stimulation. *Secrete sex phermones.

Hair bulb Forms the base of the hair follicle. In the hair bulb, living cells divide and grow to build the

hair shaft. Blood vessels nourish the cells in the hair bulb, and deliver hormones that

modify hair growth and structure at different times of life.

Sensory Nerve fibers

Piloerector muscle (arrector pili) In response to cold, fear, touch, or other stimulii, the SNS (sympathetic Nervous system)

stimulates this muscle to make the hair stand.

Lamellated (pacinian) They are nerve endings in the skin responsible for sensitivity to pain and pressure.

Corpuscle (pressure receptor) They are a type of nerve ending in the skin that is responsible for sensitivity to light touch.

In particular, they have highest sensitivity.

Motor nerve fibers The motor nerve fibers help stimulate the Erector pili muscle.

Cutaneous blood vessels

Merocrine sweat gland Sweat glands that function in evaporative cooling; widely distributed over the body

surface; open by ducts onto the skin surface.

Hypodermis (subcutaneous fat) It consists of mostly adipose tissue and is the storage site of most body fat. It serves to

fasten the skin to the underlying surface, provides thermal insulation, and absorbs shocks

from impacts to the skin.

Dermis The dermis regulates temperature and supplies the epidermis with nutrient-saturated blood. It

contains most of the skin's specialised cells and structures such as blood vessels, hair follicles, nerve

endings, lymph vessels and sweat glands.

 

 

Epidermis acts as the body's major barrier against an inhospitable  environment, by preventing pathogens from entering, making the skin a natural barrier to infection. 

Sweat pores sweat pores is actually to cool your body. When you're too hot your body releases sweat

as an attempt to cool you down. This is the primary function of sweat pores.

Hair Hair provides thermal regulation and camouflage for many animals; for others it provides

signals to other animals such as warnings, mating, or other communicative displays; and

for some animals hair provides defensive functions and, rarely, even offensive protection.

Hair also has a sensory function, extending the sense of touch beyond the surface of the

skin. Guard hairs give warnings that may trigger a recoiling reaction.

Strata and

cell types of

the Epidermis

Epidermal Layers:

Stratum corneum

Strum lucidium

stratum granulosum

Stratum spinosum

Stratum Basale

Dermal Layers:

Dermis

Papillary

Recticular

Hypodermis Layer:

Only one and called

the Hypodermis or

Subcutaneous