Histology/Histopathology

Question 1

what are the 3 embryonic layers?

Answer 1

ectoderm, mesoderm, and endoderm

Question 2

what are the 4 basic tissue types?

Answer 2

epithelial, connective, muscle, nerve

Question 3

where do epithelial tissues arise from?

Answer 3

both ectoderm and endoderm

Question 4

where do connective tissues arise from?

Answer 4

they arise from the mesoderm, but some connective tissues of the cranium, including cranial bones, arise from the ectoderm

Question 5

where do muscle tissues arise from?

Answer 5

mesoderm

Question 6

where does nerve tissue arise from?

Answer 6

it arises from the ectoderm, after first differentiating into neuroectoderm in the form of the neural tube/neural crest

Question 7

types of connective tissue

Answer 7

• connective tissue proper: cells, extracellular matrix, extracellular fibers
• specialized CT: blood, bone, cartilage

Question 8

types of muscle tissue

Answer 8

• striated: muscle, cardiac
• non-striated: smooth

Question 9

types of nerve tissue

Answer 9

• sensory/afferent
• motor/efferent
• connecting/interneurons

Question 10

after the blastocyst forms, which cell types differentiate and participate in implantation?

Answer 10

• inner cell mass (aka embryoblast)
• trophoblast: makes connection with endometrium

Question 11

what are the three types of cells making up the embryo?

Answer 11

trophoblast, hypoblast, epiblast

Question 12

which two cell types develop into the actual fetus?

Answer 12

epiblast and hypoblast

Question 13

what are the three types of embryonic tissues?

Answer 13

• ectoderm: skin, hair/glands, nervous system
• mesoderm: inner skin, muscles/bone, kidneys/bladder, gonads
• endoderm: gi tract

Question 14

define parenchyma

Answer 14

the cells in an organ that are actually responsible for the organ’s function

Question 15

stroma

Answer 15

all parts of the organ that support the parenchyma (could be connective tissue, epithelium, etc.)

Question 16

hilum

Answer 16

where blood vessels and nerves get into the organ

Question 17

general structure of a solid organ

Answer 17

• connective tissue capsule surrounding the organ
• parenchyma
• stroma
• hilum

Question 18

what is a characteristic feature of hollow organs?

Answer 18

glands and glandular secretions (in many cases, the mucosal epithelium itself is a secretory epithelium)

Question 19

layers of a hollow organ (from the outside in)

Answer 19

• serosa: epithelium, CT
• muscularis externa: outer longitudinal layer, inner circular layer
• submucosa
• mucosa: muscularis mucosa, mucosal CT, mucosal epithelium

Question 20

describe the H&E stain

Answer 20

• hematoxylin: stains acidic components like nuclear material
• eosin: stains basic components like cytoplasmic material

Question 21

describe the periodic acid-schiff stain (PAS)

Answer 21

• periodic acid: stains glycoproteins by converting them to aldehydes
• schiff: a colorless fuschin, reacts with aldehydes to form a magenta product
• important because glycoproteins are found in basement membranes, which are found in secretory tissues

Question 22

what are some glands that produce secretions by both exocrine and endocrine mechanisms?

Answer 22

pancreas and liver

Question 23

what characterizes ducts?

Answer 23

basal infoldings in their plasma membrane

Question 24

what are striated ducts?

Answer 24

they are known for ion-pumping activity by the numerous mitochondria, and they modify anything produced by the parenchyma

Question 25

define euchromatic

Answer 25

presence of euchromatin, which is dispersed chromatin that is functional and accessible for transcription

Question 26

define heterochromatic

Answer 26

presence of heterochromatin, which is condensed chromatin that is not functional and not accessible for transcription

Question 27

define basophilic

Answer 27

anything acidic, gets stained by basic dye (hematoxylin)

Question 28

define eosinophilic

Answer 28

anything basic, gets stained by acidic dye (eosin)