AHE Block 1

What is histology

the study of tissues of the body and how they are arranged

Primary components of the tissue

• cells

• ECM:support and maintenance

difference between exocrine and endocrine glands

Exocrine have epithelial lined ducts that deliver secreted material where is needs to go

Endocrine have no ducts and secrete hormones that alter the cell function

Kinds of secretion

Serous - watery (tears and sweat)

Mucous - mucus (tongue)

Seromucous - two combined

Secretion method

merocrine - secretory vesicles, cells are not damaged (sweat glands)

holocrine - cells with product rupture (sebaceous glands)

apocrine - product accumulates in apical portion of cytoplasm and decapitates (mammary gland)

Functions of connective tissue

• protect

• support

• bind

• transport

• immunity

• storage

Characteristics of CT

Cells - specific to function

Protein fibers - form ECM and provide support

Ground substances - inorganic material

Kinds of fiber

Collagen - strong

elastic - flexible

reticular - framework

Areolar tissue

loose and diverse

holds organs in place

elastic and reticular fibers

Adipose tissue

Store, cushions, and insulates

insulates body

adipocytes

reticular tissues

network support

dense regular tissue

Binding

fibroblasts

collagen fibers

dense irregular tissue

supports and binds

joints

collagen fibers

Simple squamous cells

movement of cases

respiratory and cardiovascular

Simple cuboidal

movement of fluids across the cell barrier

urinary

Simple columnar

absorption and secretion (microvilli)

digestive and reproductive

Pseudostratified

Absorption and secretion across free surface

respiratory

Stratified squamous

protection n

skin

oogenesis

1. oogonia in ovary undergoes mitosis

2. primary oocyte begins meiosis 1 and arrests in prophase

3. after puberty the primary oocyte completes meiosis 1

4. secondary oocyte starts meiosis 2 and arrests in metaphase (here until fertilization)

Follicular phase

1. primary follicle: primary oocyte and follicular cells

2. secondary follicle: primary, zona, and small antrum

3. mature follicle: secondary and large antrum

4. ovulated structure: secondary and corona

Spermatogenesis

1. spermatagonia goes through mitosis

2. primary spermatocyte goes through meiosis 1

3. secondary spermatocyte goes through meiosis 2

4. spermatids then form and morphologically change

5. sperm

Cell stages vs follicular stages

Cells tell us about what is happening during development and follicular tells us about the structures

Fertilization 12-24 hours after ovulation

1. sperm penetrates corona then zona of secondary oocyte

2. zona hardens to prevent entry

3. plasma membranes fuse so only the sperm nucleus enters

4. secondary oocyte finishes meiosis 2 and becomes ovum

5. ovum and sperm create diploid zygote

Fertilization 30 hrs - day 6

1. zygote undergoes mitosis increasing cell number

2. morula forms around day 3

3. Blastocysts - embryoblasts(epiblast and hypoblast), blastocyst cavity(yolk sac), and trophoblasts

4. implantation occurs late in the first week

Implantation

this occurs when the blastocyst adheres to the wall

1. blastocyst embeds in endometrial lining

2. syncytiotrophoblasts die digging into the connective tissue

3. apoptosis facilitates implantation

Major structures formed

• bilaminar embryonic disc: former embryoblast, tissues and organs of embryo

• amniotic cavity: forms amniotic sack and will protect fetus

• umbilicle vesicle: yolk sac, formed from blastocyst cavity, provide nutrients until placenta is formed

• chorion: helps form placenta