Histology - Connective Tissue Part 2

slender fibrils, no bundling.

Heavily glycosylated. Fibrils only. First collagen laid down in embryo and after an injury.

Surround: Adipocytes, smooth muscle fibers, prepheral nerve fibers, small blood & lymph vessels (microcirculation). Also a major component of the reticular lamina that underlies the basal lamina.

Forms a delicate latticework (network) providing support for organs that: 1. filter blood or lymph (spleen, lymph nodes) 2. Have rich microvasculature (liver, GI tract, encocrine organs) and 3. Have rapidly changin populations of proliferating cells (bone marrow).

Monomers form flat sheet-like meshwork. No fibrils (no periodicity). Found in basal lamina (epithelium) and external lamina (muscle & nerve). Provides support (epithelium) and filtration.

Anchoring, non-fibrillar. Anchors basal lamina to reticular lamina.

From mesenchyme, which is sourced from mesoderm and neural crest. Mesenchyme-like cells, retained in adult CTs are source of stem cells.

Fribroblast, Chondrocyte, Adipocyte

Benign: lipoma. Malignant: Liposarcoma

Benign: Chondroma. Malignnant: Chondrosarcoma

Principal CT cell. Synthesizes & secretes all ECM components.

Numerous cells in close proximity, cell structure reflects intense synthetic activity, gwoth or repair within 2 hours after injury. Secrete type III collagen. Later replace type II with type I.

Quiescent fibroblast. Fewer cells, more widely dispersed. Reduced activity, ECM maintenance.

Protein-secreting cell containing bundles of actin filaments (contractile). Most active during 1st week (2nd week: undergo apoptosis). Generate & maintain steady contractile force (approximate tissues) Assist with synthesis & secretion initial ECM (quick repair).

Arise from monocytes (white blood cell) after migration from blood into CT, whereafter they are considered resident CT cells.

1. 1. Host response to injury: Inflammation. 2. Host defense.

Large cells, eccentric nuclei, pften appear vacuolated

Features of a phagocytic cell

When macrophages encounter large foreign bodies, they may fuse to form a very large cell. These very large cells engulf or “wall-off” the foreign body.

Preformed chemical mediators of inflammation. Secrete Cytokines & Leukotrienes. Skin, Respiratory & GI systems.

Anticoagulant mast cell. (a GAG).

A mast cell that promotes increased vascular permeability, intense smooth muscle contraction, and mucus secretion by nasal & bronchial glands.

Most common type of fat cell. Large, spherical cells with eccentric nucleus and thin rim of cytoplasm that synthesize and store lipids as TAGs for energy and secrete hormones, growth factors, and cytokines.

(brown) fat cells located in brown adipose tissue. Function: Heat generation (thermogenesis)

1. 1. Develop elsewhere (bone marrow) 2. Migrate into CT’s to perform their functions 3. Short-lived: White blood cells and Plasma cells

Oval-shaped cell (tear drop), Eccentric nucleus, Prominent nucleolus, Heterochromatin distributed in “Clock-face or Cartwheel” pattern.

Comprises the functional parts of an organ. Liver = hepatocytes.

The connective, supportive framework of a biological cell, tissue, or organ.

Epithelium + Lamina propria

Simple columnar with brush border + goblet cells

Mesenchyme
Mucous

Lies immediately deep to epithelium surrounds blood vessels

Tendons
Ligaments
Aponeuroses