Histology and Embryology Jicheng LI Zhejiang University Medical School

Reference books 1.唐军民、李继承.组织学与胚胎学（Textbook of Histology and Embryology），北京大学医学出版社，2011年1月。 2.Junqueira LC, Carneiro J, Kelley RO. Basic Histology. 9th ed. New York: Appleton & Lange, Stamford, Connecticut, 1998 3.Gaetner MP, Hlatt JL. Colour Textbook of Histology. Williams & Wilkins, 1997 4.Su Huici. A Textbook of Histology. China Science and Technology Press, Beijing

Chapter 1 Introduction

I.     What’s histology? II.    Why we study it ? III.   How to study it ? -Histological methods.

I. What’s histology? Histology (Greek words): /histo-tissue /logia-study of ,or knowledge of Histology means the knowledge of tissue, is a branch of Anatomy.

Anatomy: ---gross anatomy ---microscopic anatomy -- microanatomy structures related to function. Histology is a science which study the microstructure and the relationship between the structure and function of human being.

Cell: smallest unit of structure and function of body ↓ tissue: group of cell and extracellular ground substance four basic tissue: --- epithelium ↓ --- connective tissue --- muscular tissue --- nervous tissue organ: made up of tissue, have special shape, structure and function system: organs which have related function get together.

II.What’s Embryology? Embryology is a kind of science which study the processes and the regulations of the development of human fetus. 1.Preembryonic period 2.Embryonic period 3.Fetal period

III. How to study it- histological methods ---Development of histology depends on the development of technique. ---Histology studies the microstructures. So, we should have the aid of microscope to study. Several types of microscopes are available.

Some Instruments for Histologcal Research

Light Microscopy

Preparation of tissue for LM The most routine one is paraffin section stained with hematoxylin and eosin(H&E) The steps: a. Obtaining the specimen: fresh, small pieces ( less than 5mm3)-tissue block b. Fixation: use formalin or Bouin’s to preserve structural organisation c.  Dehydration: use ethyl alcohol to get rid of water of tissue and cell

d.  Clearing: use xylene to get rid of alcohol *alcohol and xylene are embedding mediums e.  Embedding: firstly, heat the paraffin, make it melt, then put tissue block into melted paraffin, allow paraffin harden, the tissue block is embedded in.

f.   Sectioning: use microtome to cut the tissue into 3-8um thick sections, then mounted them on glass slides

g.   H&E staining ---Hematoxylin: basic stain, combines with acidic components, make them appear blue colour- basophilic, i.e. cell nucleus, hyaline cartilage ---Eosin: acidic stain, combines with basic components, make them appear pink colour- acidophilic (eosinophilic), i.e. cytoplasm

 H&E staining

TEM

Preparation of tissue for EM The steps are same to preparation for LM a.   tissue block: more small, less than 1mm3 b.   plastic materials for embedding c.  ultra-thin sections is about 30-50nm thick( use ultramicrotome) d.   heavy metal salts- increase staining contrast ---lead citrate ---uranyl acatate

Basophilic granulocyte (TEM) 在血涂片上很难找到…因为数量少。 C核呈“S”形，染色浅，轮廓不清楚。 胞质含有许多大小不等，分布不均的紫蓝色的嗜碱性颗粒。 EM：大量的嗜碱性颗粒，圆形椭圆形。 颗粒内有时可见板层状结构。 Basophilic granulocyte (LM)