DERMIS (CORIUM) -

• Mesodermal in origin. More developed part.
• Leather is obtained from dermis by tanning. Thinnest in eye lid. Connective tissue present.
• In it 4 types of cell are present -

(i) Fibroblast or fibrocyte - forms fibres attached to fibres.

(ii) Histocytes - Amoeba like, phagocytic in nature.

(iii) Plasma cells - formation of antibodies (g-globuline)

(iv) Mast cells - It forms matrix, heparine & serotonine.

• Collagen & elastin fibres are present.
• When elasticity of dermis is lost skin becomes wrinkeled.
• Dermis consists of b.v., lymph, vessels, unstripped muscles, nerves etc.
• Sensory papillae present in dermis (not in epidermis to avoid unnecessary stimulation).
• These papillae are of following types -

(i) Genital corpusulses - On tip of penis & clitoris.

(ii) Vater pecinian corpusulses or baroreceptor - For pressure deeply placed. More in palm & sole.

(iii) Frigido receptor or end bulb of krausi - For cold.

(iv) Allgesi receptor - For pain. Attached to free nerve endings mainly.

(v) Endings of Ruffini or Calore receptor - For hot.

(vi) Tectile corpuscles or missnner's corpuscles or markle's disc - For touch. Markel's disc is diffterent from other in structure.

(vii) Vibreo receptor - For vibration. Basal part of dermis is peniculus adiposa present on hypodermis (not a part of skin). Fat is stored in it. Also helpfull in temp. regulation. This part is absent in eye lid, prepuce & scrotal sac.

• Outer part of dermis is papillary part or pars papillaris in it dermal papullae present, fibres are dense, lines of langerhanse can be seen.
• Inner part is reticulate part or pors reticularis, papullae are absent, fibres are scattered.
• In dermis melanophage cells engulf melanin by phagocytosis.
• In some area of dermis blood passes from artery to vein directly by shunt or arterioveinuous anastamoses.