A. simple squamous epithelum (is continuous with urinary tract)

B. simple cubodial epithelium (This form represents an intermediate form between simple squamous and
simple columnar epithelium. In cross sections, the cells appear square; on surface view, the cells are
actually polygonal in shape. Simple cuboidal epithelium usually lines small ducts and tubules which
may have excretory, secretory, or absorptive functions; examples are the small collecting ducts of the
kidney, salivary glands and pancreas.)

Simple Squamous Epithelium
surrounds lumen and
capillary bed of glomerulus

Simple Cuboidal Epithelium
surrounds the lumens of
most tubes seen in cross section

(this is from your kindey. the big round thing is a glomerulous)

Stratified Squamous Epithelium has a basement
membrane (line between light pink and fuschia) and epithelial stem cells (purple dots throughout)

The major function of this type of epithelium is
protection against mechanical abrasion. This section shows several layers of epithelial cells and the
basement membrane. Cells closest to the basement membrane appear cuboidal and are actively
dividing but the outermost layer of epithelia consists of squamous cells, so this epithelium is classified
as stratified squamous. This type of tissue is found in the oral cavity, pharynx, esophagus, anal canal and
vagina.

cells: eythrthrocytes and lympoctyes

; matrix: plasma

; fiber: fibrogen

ligaments and tendons are made up of this kind of tissue

This tissue differs from loose fibrous connective tissue
in that its elastin and collagen fibers are tightly packed together
and are all oriented in the same direction, thus
increasing strength and elasticity in that direction.   
These fibers are wavy in shape, and are closely packed in bundles, giving the tissue a characteristic
wavy appearance. Between the bundles may be seen the flattened fibroblasts arranged in rows.

simple columnar epithelium (duodenum), villi projecting into the lumen of the small intestine x100

At 10x magnification,
search for an area of the slide that has finger-like projections surrounding a lumen - these are the villi.
Switch to 40x. Cells are tall and columnar, at right angles to the basement membrane. The nuclei are
elongated and may be arranged toward the base, the center or occasionally the apex. Simple columnar
epithelium is most often found on highly absorptive surfaces such as in the small intestine, although it
may constitute the lining of highly secretory surfaces such as that of the stomach.

simple columnar epithelium, duodenum, x400; the little purple dots are goblet cells

At 10x magnification,
search for an area of the slide that has finger-like projections surrounding a lumen - these are the villi.
Switch to 40x. Cells are tall and columnar, at right angles to the basement membrane. The nuclei are
elongated and may be arranged toward the base, the center or occasionally the apex. Simple columnar
epithelium is most often found on highly absorptive surfaces such as in the small intestine, although it
may constitute the lining of highly secretory surfaces such as that of the stomach.

psuedostratified cilitated columnar epithelium- lines the lumen of trachea and bronchial tubes, 100x. the top red line is epithelial cells, the bottom part with purple dots is cartilage

Pseudostratified ciliated columnar epithelium (thin section) gives one the erroneous
impression that there is more than one layer of cells. However, all the cells rest on the basement
membrane (although not all cells extend to the luminal surface), so it is a simple epithelium. The nuclei
are disposed at different levels, thus creating the illusion of cellular stratification. Notice the border of
cilia on the luminal side. This type of tissue is almost exclusively confined to the larger airways of the
respiratory system (i.e., trachea) and therefore often is referred to as respiratory epithelium. What do you
suppose is the function of this tissue?

psuedostratified ciliated columnar epithelium, 400x. the line of purple dots is the basement membrane- the litte pink whispy things on top are the cilia

Pseudostratified ciliated columnar epithelium (thin section) gives one the erroneous
impression that there is more than one layer of cells. However, all the cells rest on the basement
membrane (although not all cells extend to the luminal surface), so it is a simple epithelium. The nuclei
are disposed at different levels, thus creating the illusion of cellular stratification. Notice the border of
cilia on the luminal side. This type of tissue is almost exclusively confined to the larger airways of the
respiratory system (i.e., trachea) and therefore often is referred to as respiratory epithelium. What do you
suppose is the function of this tissue?

stratified squamous keratinizing epithelium is skin, 100x

the layers of red stuff on the top are keratinized dead cells, and the line of purple below are live stem cells

The major means of epithelial
tissue protection is through the production of the protein keratin. Cells have different amounts of this,
which alters their characteristics. This specialized form of tissue constitutes the epithelial surface of the
skin and is adapted to withstand constant abrasion and dessication; the cells of the skin become
engorged with keratin, lack nuclei, appear scale-like and eventually die. Cells with lesser amounts
exhibit "non"-keratinization — they have nuclei, appear alive. The tough non-cellular surface of skin,
then, is composed of the protein keratin and the remnants of degenerate epithelial cells.

stratified squamous keratinizing epithelium, 400x; dead enucleated outer cells- gross!

The major means of epithelial
tissue protection is through the production of the protein keratin. Cells have different amounts of this,
which alters their characteristics. This specialized form of tissue constitutes the epithelial surface of the
skin and is adapted to withstand constant abrasion and dessication; the cells of the skin become
engorged with keratin, lack nuclei, appear scale-like and eventually die. Cells with lesser amounts
exhibit "non"-keratinization — they have nuclei, appear alive. The tough non-cellular surface of skin,
then, is composed of the protein keratin and the remnants of degenerate epithelial cells.

stratified squamous keratinizing epithelium, 400x

live epithelial stem cells are blue stained

The major means of epithelial
tissue protection is through the production of the protein keratin. Cells have different amounts of this,
which alters their characteristics. This specialized form of tissue constitutes the epithelial surface of the
skin and is adapted to withstand constant abrasion and dessication; the cells of the skin become
engorged with keratin, lack nuclei, appear scale-like and eventually die. Cells with lesser amounts
exhibit "non"-keratinization — they have nuclei, appear alive. The tough non-cellular surface of skin,
then, is composed of the protein keratin and the remnants of degenerate epithelial cells.

ureter 100x

the white stuff on the outside is adipose tissue

the lumen (white, innermost part of the circle) is surrounded by pink transitional epithelium and darker red smooth muscle

Transitional epithelium, thin section (cross section of a ureter). This form of stratified
epithelium is almost exclusively confined to the urinary tract in mammals, where it is highly specialized
to accommodate a great degree of stretch and to withstand the toxicity of urine. It is so-named because it
exhibits features intermediate between stratified cuboidal and stratified squamous epithelium. In the
relaxed state, this tissue appears to be approximately 4-5 cells thick; basal cells are roughly cuboidal,
intermediate cells are more flattened or polygonal, and the surface cells are large and rounded. Notice
that the plasma membranes of the surface cells are quite thick to provide a permeability barrier. Notice
the two layers of smooth muscle surrounding the epithelia; the inner layer is longitudinal and the outer
layer is circular. The next portion of the section is loose connective tissue and the outermost portion is
adipose tissue (fat cells).

transitional epithelial cells, 400x

easily changes shape

Transitional epithelium, thin section (cross section of a ureter). This form of stratified
epithelium is almost exclusively confined to the urinary tract in mammals, where it is highly specialized
to accommodate a great degree of stretch and to withstand the toxicity of urine. It is so-named because it
exhibits features intermediate between stratified cuboidal and stratified squamous epithelium. In the
relaxed state, this tissue appears to be approximately 4-5 cells thick; basal cells are roughly cuboidal,
intermediate cells are more flattened or polygonal, and the surface cells are large and rounded. Notice
that the plasma membranes of the surface cells are quite thick to provide a permeability barrier. Notice
the two layers of smooth muscle surrounding the epithelia; the inner layer is longitudinal and the outer
layer is circular. The next portion of the section is loose connective tissue and the outermost portion is
adipose tissue (fat cells).

blood, 100x

Blood and lymph are good examples of connective tissues with liquid
matrices. In blood, the erythrocytes, or red blood cells, and the leukocytes, or white blood cells, are
floating in the plasma, which is the liquid matrix. The fibers are the soluble protein fibrinogen; when
clotting occurs, fibrinogen is converted into fibrin fibers which make up the clot. Notice the erythrocytes
with purple-stained leukocytes interspersed randomly throughout. (You'll notice that the leukocytes have
different appearances — there are several classes of them.) Also, small platelets can be seen, which
appear as tiny purple dots between cells. Question: why don't erythrocytes pick up the purple stain?

red blood cells are red stained

white blood cells are blue stained

plasma is the matrix

fibrinogen (unpolymerized) is the fiber

Blood and lymph are good examples of connective tissues with liquid
matrices. In blood, the erythrocytes, or red blood cells, and the leukocytes, or white blood cells, are
floating in the plasma, which is the liquid matrix. The fibers are the soluble protein fibrinogen; when
clotting occurs, fibrinogen is converted into fibrin fibers which make up the clot. Notice the erythrocytes
with purple-stained leukocytes interspersed randomly throughout. (You'll notice that the leukocytes have
different appearances — there are several classes of them.) Also, small platelets can be seen, which
appear as tiny purple dots between cells. Question: why don't erythrocytes pick up the purple stain?

loose fibrous connective tissue, 100x

the fibroblasts are the cells

collagen and elastin are the matrix fibers

Loose fibrous connective tissue or areolar tissue (spread) is widespread throughout the body,
functioning to bind together the individual cells of muscles and nerves, to bind organs together and hold
them in place, etc. In other words, it acts as a biological packing material between other tissues of more
specific functions. The matrix includes some large, tough collagen fibers (pink stained) and some thinner
elastin fibers (blue stained); both types of fibers are produced by the purple stained fibroblasts. As you
can see, in loose connective tissue the fibers are not packed tightly together and they are oriented in
many different directions.

tendon 400x

the fibroblasts are the cells

the collagen and elastin are the matrix fibers

the darker pink stuff in the picture is the skeletal muscle

Tendon, long section, thin section. Tendons, which
connect muscles to bones and ligaments, which connects bones to other bones, are composed of dense fibrous connective tissue. This tissue differs from loose fibrous connective tissue in that its elastin and collagen fibers are tightly packed together and are all oriented in the same direction, thus increasing strength and elasticity in that direction.  
These fibers are wavy in shape, and are closely packed in bundles, giving the tissue a characteristic
wavy appearance. Between the bundles may be seen the flattened fibroblasts arranged in rows.

adipose, 400x

the fat cells are called adipocytes

there is no extracellular fibers or matrix

Surrounding the ureter, adipose or fat tissue is a
modified type of connective tissue. The stored fat occupies a large part of the contents of the cells
(adipocytes) so that only a small margin of cytoplasm and the nucleus can be noted around the cells.
This gives the cells a ring-like shape. Fat tissue is not only important in nutrient storage, but also in
protection of other tissues, insulation, and padding.

hyaline cartilage, 100x

the chondrocytes are the cells

the collagen and elastin are the matrix fibers

the purple dots on the bottom hald are lacunae with chondrocytes

Hyaline cartilage, thin section. [Look at the center of the section.] This type of cartilage is
the most abundant form in the body. It has a firm rubbery matrix consisting of many tightly packed
collagen fibers. Cartilage fibroblast cells, called chondrocytes, are located in small spaces called
lacunae, which are scattered throughout the matrix. Cartilage varies in its texture, color, and elasticity. It
is found in the body in such places as the nose, larynx, trachea, ear, intervertebral discs, and many parts
of the skeleton. From where in the body do you suppose this slide was taken?

elastic cartilage, 100x

the chondrocytes are the cells

the collagen and MORE elastin are the matrix fibers

the pretty red/purple ovals are lacunae with chondrocytes

 This slide has been stained so that elastin fibers appear black. Your slide might contain hair follicles located on either side of the cartilage. In mammals, this type of cartilage is found in the external ear, in the walls of the external auditory and eustachian tubes, and in the epiglottis.

developing cartilage bone- osteogenic zone, 400x

inside the lacy purple part are osteocytes invading cartilage

Developing cartilage bone, thin section. The immature skeleton of the fetus is initially made
up of mostly cartilage. Eventually, through a complex process known as ossification, the cartilage is
calcified and replaced by bone. What you see in the slide is the interface between the shaft of this fetal
bone and its end, or epiphysis. The shaft is comprised of marrow space surrounded by immature bone
and is stained pink. The epiphysis is cartilagenous and is stained purple-gray. This area constitutes a
growth plate where chondrocytes proliferate and eventually degenerate away from the epiphysis to give
way to deposition of bone tissue; this zone of proliferation is responsible for the elongation of bone.

Compact Bone, Ground, 100 X
Cells: Osteocytes
Matrix Fibers: Collagen, Calcium Phosphate Coated

Compact bone, ground (from the human femur). Bone has a hard, relatively rigid matrix
comprised of numerous collagen fibers which are impregnated with calcium deposits. Compact bone
consists of numerous structural units called Haversian systems. Each Haversian system is seen as a
nearly round area, the central core of which is the Haversian canal, which runs lengthwise through the
bone. Bone is living tissue; the blood vessels, lymph vessels, and nerves that supply the tissue run
through the Haversian canal. Around the canal is the matrix, arranged in concentric layers called
lamellae. The lamellae are perforated by lacunae where the osteocytes, the fibroblasts of bone cells, are
located. (The lacunae are visible as flat dark spots.) Numerous fine canaliculi interconnect lacunae and
Haversian canals to provide the resident osteocytes with tissue fluid and metabolites.

skeletal muscle, 400x

multinucleate

voluntary

Skeletal muscle (or Striated muscle), cross section, thin section. Skeletal muscle fibers are
extremely elongated unbranched cylindrical cells; they may be up to several centimeters in length, while
their diameter is approximately 20-100 µm. Each fiber is multinucleate, containing a great many
flattened peripherally located nuclei at fairly regular intervals. The fibers are crossed by numerous
alternating light and dark bands, or striations, providing this tissue with its name. These bands are the
result of the arrangement of the contractile proteins, which are responsible for the peripheral
displacement of the nuclei. The fibers of skeletal muscle are bound together into bundles by delicate
connective tissue.

smooth muscle, 400x

no striations; involuntary

Smooth muscle (or visceral muscle), thin section. (From the intestine; look around the
periphery of the section.) Smooth muscle is found encapsulating the blood vessels and lines such
structures as the intestinal tract, the uterus, and the bladder. Note the absence of striations. Each fiber is
elongate, pointed at each end, and contains a single centrally located rod-shaped nucleus. Smooth
muscle fibers interlace to form sheets of muscle rather than bundles. It might appear to you that smooth
muscle looks like fish swimming.

cardiac muscle, 400x

intercalcated disks are horizontal lines

involuntary

Cardiac muscle, thin section. The cells of cardiac muscle branch and interdigitate, forming a
complex three dimensional network. You'll see in the slide that where adjacent cardiac muscle cells meet
are dark staining, specialized intercellular junctions called intercalated discs; these not only provide
points of anchorage for the myofibrils but also permit extremely rapid spread of contractile stimuli from
one cell to another, resulting in nearly simultaneous contractions. The one or two nuclei are round or
ovoid and are centrally located within the cells. Note that cardiac muscle has striations but the striations
are not as organized as those of striated muscle.

central nervous system, spinal cord squash, 100x

Neurons, squash (from spinal cord). Each neuron consists of a cell body in the central
nervous system (the balloon-like structure). The cell body portion containing the nucleus, and from it
extend long, thin fiber-like processes called dendrites and axons. The purple dots throughout the
section are glial cells, the nutritive and support cells of the central nervous system. The axon of a motor
neuron may be several feet long and exits the central nervous system to synapse with a skeletal muscle
cell.

neuron- cell body portion, 400x

surrounded by squashed glial cells

Neurons, squash (from spinal cord). Each neuron consists of a cell body in the central
nervous system (the balloon-like structure). The cell body portion containing the nucleus, and from it
extend long, thin fiber-like processes called dendrites and axons. The purple dots throughout the
section are glial cells, the nutritive and support cells of the central nervous system. The axon of a motor
neuron may be several feet long and exits the central nervous system to synapse with a skeletal muscle
cell.

Peripheral Nerve
Cross Section, 100 X
Axon portions of
Neurons
with
Schwann
Cells

Peripheral nerve. There are three basic parts to the peripheral nerve: the perineurium,
epineurium, and endoneurium. They provide several layers of protection around the nerve fibers. The
purple dots represent Schwann cell nuclei. These cells wrap around individual nerve fibers creating
insulated channels. Individual nerve fibers may be efferent or afferent.

group of circles in middle is the peripheral nerve bundle

to the top right of that, the smaller squished oval structure is the artery- the outside is smooth miscle and the inside blue part is stained elastin on the artery endothelium surface

the very long, squished oval on the right is the vein

Small neurovascular
bundle comprised of an artery,
vein and nerve. The vessels
supplying and draining a partic-
ular area of tissue tend to pass
together, frequently accompanied
by a peripheral nerve and surrounded by connective tissue which forms an ill-defined protective sheath. This slide shows that the three
components lie in loose areolar connective tissue and are surrounded by a more condensed collagenous
sheath. Notice that the artery has a rigid wall compared to the collapsed appearance of the vein. This is
because the inner walls of the artery are largely made up of elastin to provide for the expansion and
recoil necessary for the maintenance of the blood pressure. In smaller arteries and arterioles, the
diameter of the lumen is regulated by smooth muscles in the vessel walls and is under the control of the
sympathetic nervous system.

what kind of tissue is the best at contracting?

what kind of tissue is the best at being irriatated?

muscle

--------

nervous

1) Epithelial Tissues - Linings of ducts, GI, Urinary and Respiratory tracts and Skin.

2) Connective Tissues - Support Tissues composed of cellular components with matrix of
extracellular protein fibers and glycoproteins (except adipose which has no fibers or matrix).

3) Muscle and Nerve - Have action potentials, cells highly specialized with unique shapes & features.

The SA Node is the Heart’s Pacemaker, initating atrial depolarization.   
 
SA Node cells have leaky to Ca++ membranes & depolarize c. 1/sec at rest

The AV Node inserts a delay before passing on depolarization.   

After delay, the AV node send depolarization signal through the bundle of His to Purkinjie fibers to depolarize ventricles

1- ventricular filling

2- isovolumetric ventricular contraction

3- ventricular ejection

4- isovolumetric ventricular relaxation

endocardium (inside)

epicardium (outside)

the pulminary circuit is the right side of the heart that recieves deoxygenated blood from the body and pumps it to the lungs

the systemic circuit is the left side of the heart that recieves the oxygenated blood from the lungs and pumps it to the rest of the body

you need the systemic pressure to be high (if its too low, you have poor delivery of blood to the tissues)

BUT if you were to have that high of pressure also in the pulminary circuit, you would get pulminary edema (fluid accumulation in the lungs)

@ placenta: fetal blood picks up O2, drops off CO2

oxygenated blood goes through

fertilization!

fertilization (haploid sperm + haploid egg) results in a zygote.

zebrafish zygotes surrounded by thin transparent membrane called chorion which prevents polyspermy

this single cell's cytoplasm that migrates around the yolk to the animal pole (dorsal surface) forms the blastodisc.

the early cleavage period!

cleavage is cell division without overall change in embryo size

cells formed from cleavage are blastomeres

a. first: vertical cleavage (animal pole to vegetal pole)

b. second: cleavage vertical, but 90 degrees to first cleavage

early cleavages make equal size daughter cells and are synchronous

in zebrafish, there is meroblastic cleavage where cleavage is restricted to blastodisc and does not penetrate yolk

in some other organisms, there is holoblastic cleavage where cleavage plane cuts through the entire cell, including the yolk

blastula period!

cell is now a blastoderm (128 cells)

water is pumped into interior of embryo, and the early blastula is a ball of cells with clear, irregular spaces in between them

features include YSL (formed by blastomeres that had sat on the surface of the yolk, fusing and releasing their cytoplasm and nuclei into the cytoplasm of the yolk cell)

also, during the blastula period, epiboly goes down

from lab practical study guide:

Yolk Syncytial Layer (YSL) forms through syncytial cell division of cells adjacent to yolk
during blastula stages. During High Stage, the blastoderm is a high mound of cells sitting on a
flat YSL surface on the yolk cell.

from lab itself:

The blastomeres that sit on the surface of the yolk have remained connected to it throughout cleavage
via the cytoplasm. These cells now fuse and release their cytoplasm and nuclei into the cytoplasm of the
yolk cell to form the yolk syncytial layer or YSL. The YSL nuclei continue to undergo mitotic divisions
for about 3 cycles, but the cytoplasm of the YSL stays together and does not cleave.

The YSL is a developmental structure characteristic of bony fish (teleosts). At first the YSL forms a ring
around the edge of the blastodisc; the ring then spreads until it forms a border between the embryo and
its yolk, eventually covering the entire surface of the yolk (see epiboly on the next page). The YSL
membrane thus separates the embryo proper from the yolk, which contains nutrients that were deposited
by the embryo’s mother. The correct expression of enzymes in the YSL cytoplasm and numerous solute
transporters at the YSL membrane is vital for the transport of minerals and food stores out of the yolk,
until the embryo has developed mouth structures and swimming abilities that permit it to feed (at day 4
and 5 of development).

from lab practical review:

beginning at Dome stage. Blastoderm begins movement from animal pole
around the yolk cell toward the vegetal pole.

from actual lab handout

 
In the “high stage,” the yolk is flattened and the blastodisc is a high mound of cells upon it. 

Subsequently the animal-vegetal axis shortens, two stages pass, and the YSL surface begins to dome towards the animal pole. This is the “dome stage” (4.33 hpf), and it is an obvious sign that epiboly is beginning.

During epiboly, the YSL and blastodisc thins and moves to spread completely over the surface of the
yolk cell; it is now called blastoderm. The yolk cell itself bulges towards the animal pole.  

If 50% of the distance between the poles along the animal-vegetal axis is covered with blastoderm, then
the embryo’s stage is 50% epiboly.

from lab pracitcal handout: 

a) Morpholino injection – artificial oligonucleotides that block specific genes usually by binding to a particular mRNA (used to make oep morphant).
   b) small molecules that block a receptor in target cells, preventing the expression of a particular gene or set of genes (used to make ntl morphant).

from in class lab handout:

Morpholinos are short artificial oligonucleotides that can combine with RNA or DNA in a cell. Scientists
design particular base pair sequences for a Morpholino so that it will bind to a specific target gene or its
mRNA silencing its expression. The Morpholino molecules are then injected into a zygote. By observing
changes in morphology of the treated embryos, scientists can elucidate the function of that gene in development. By observing which structures are not formed in the morphant, scientists can learn what
the normal function of the targeted gene is.

top arrow is pharyngeal arches

bottom arrow is eye

Cartilage Staining
1) Week old embryos are fixed in TCA and preserved in acid ethanol.

2) Replace acid ethanol with 0.1% Alcian Blue dye. Alcian bue specifically stains cartilage.

3) Destain with acid/ethanol.

4) Clear with KOH/Glycerol solution

5) Observe cartilage structures which remain blue, such as the pharyngeal arch of the jaw, gill arches, neck vertebrae, fins, etc.

how does one form a fish that was mutated during development?

by introducing a morphogen (articifically created and specific morphagens are morpholinos)

the morphagen canprevent proper communication between cells, by preventing normal turning on of transcription of mRNA from genes. this defect in a gene causes a change in development. Most mutations are recessive and require inheriting the mutant allele from both parents to express the phenotype.

oep One Eyed Pinhead (ALK inhibitor drug morphant)

a result of a +nodal signaling inhibitor (morphilino morphant phenotype)

Morphant Phenotype: no trunk, no endoderm (gut,
liver etc), no mesoderm except somites in the tail
(no heart, blood, hatching gland, notochord; dorsal
aorta; cyclopia; ventral nervous is missing).

no tail (ntl)

ALK receptor kinase inhibitor morphant phenotype

ntl morpholino induced Phenotype: no tail;
horizontal myoseptum missing; somites are
C-shaped instead of chevron (〈) shaped.

caspar mutation

Caspar has genotype roy-/- , phenotype: dark eyes and genotype nacre-/-, phenotype: totally unpigmented skin with no silvery reflective cells (iridophores) and no dark pigmented cells (chromophores)

hg, hatching gland

fb, forebrain

mb, midbrain

hb, hindbrain

nc, notochord

sc, spinal cord

fp, floor plate.

Gastrulation period!

Epiboly pauses at the 50% level. At Embryonic Shield stage, cells form a bulge on the inner edge of the blastoderm. Embryonic layers form during gastrulation beginning with epiblast and hypoblast, which will further differentiate into ectoderm, mesoderm and
endoderm. Epiboly restarts and embryo thickens at the dorsal side where the shield once was.
 

At 90% Epiboly cells form the flat neural plate near the animal pole on the dorsal side of the
embryo, which then curls on itself to form the neural tube. This starts the process of neurulation,
leading to the formation of the nervous system.

 Segmentation period!

Chevron shaped somites develop along the notochord.

Neurulation continues with brain and spinal chord forming, the head develops with eyes and ears forming.

Organs begin to form, tail bud becomes prominent and lengthens, first body movements appear.

Pharyngula Period!(24-48hr)

Named for the formation of pharyngeal arches (form the
jaws and gills).

Embryo continues to lengthen, fins begin to form, pigment
cells become visible, eyes begin to darken, heart begins to beat (c. 24hpf).

Blastodisc

forms as Zygote’s cytoplasm moves around yolk to animal pole. (Chorion removed)

here you can see the shield!

As gastrulation proceeds, the organization of the body plan of the zebrafish begins with a bulge of cells
called the embryonic shield that forms at one side of the blastoderm at shield stage. Once the embryonic shield forms, epiboly continues at a rate of ~15% per hour while gastrulation continues.

Neural Plate

begins forming at 90% Epiboly. This begins the formation of the Neural Tube which will become the brain and spinal chord.

(while the gastrulation period begins at 50% epiboly, the gastrulation process actually begins at the shield stage)

draw a little picture of a rat and see if you can label it with the following terms: 

cranial

caudal

rostral

dorsal

ventral

distal

proximal

left

right

lateral

medial

Cranial means “towards the head”

caudal, “towards the tail”.

Rostral means “toward the nose,” and is typically used when talking about the head.

Dorsal refers to the back of the body of an animal (the upper surface in rats)

ventral, to the belly (the undersurface in rats).

The terms distal and proximal describe the relative distance from the roots of the limbs; for
example, the shoulder is proximal to the forelimb and the foot is distal to the forelimb of a rat.

Left and right are self-evident, but remember that in anatomical directions they always pertain to the
specimen's left or right, regardless of the way the specimen is viewed by the observer.

The midline is an imaginary line that goes from the head to tail of an animal through the center of the body.

Lateral refers toward the side of the body (either right or left). Medial means nearer to the midline.

draw a little picture of a rat and see if you can label the following planes and sections:

longitudinal axis

sagittal section

parasagittal section

frontal section

transverse plane

transverse cross section

The longitudinal axis describes the direction from the caudal to cranial end of the animal.

A longitudinal, vertical section along the midline from the cranial to the caudal end is a sagittal section.

Such a section lies in the sagittal plane.

Sections or planes parallel with, but lateral to the sagittal plane, are often referred to as parasagittal.

A frontal section or plane also lies on the longitudinal axis, but horizontally at 90° from the sagittal
plane; also passing from the cranial to caudal end, but dividing the dorsal from the ventral.

The transverse plane is 90° from the two longitudinal planes and the midline. A section cut through the
body at right angles to the longitudinal axis is a transverse or cross section.

abdominal cavity is aka peritoneal cavity

the muscular diaphragm is the upper border (is made of skeletal muscal fiber, the diaphragm's contactions create negative pressure in the thoraic cavity and this powers inflating the lungs)

parietal peritoneum: lines the abdominal wall

visceral peritoneum: overlies the organs

both produce fluid which lubricates the organs

 Portal vein is the term for a vein between two organs or two capillary beds, unlike the usual arrangement of artery —> capillary bed —> vein.

The incoming blood comes from the small intestines to the mesenteric veins (from the small intestines) and enters the hepatic portal vein.

This vein branches repeatedly as it enters the liver until it forms sinusoids, a sort of specialized capillary bed. Out-flowing blood enters the hepatic vein from each lobe. These veins join the vena cava as it passes through the liver.

There is also an artery that supplies oxygenated blood to the
liver.

duodenum

jejunum

ileum* is a fan linke array connected by mesentary and mesensteric blood vessels to a central artery and hepatic portal vein

each have different morphology of simple columnar epithelium cells that comprise their inner linigs

the cecum (beginning of the colon)

nope, we only have appendix

ascending

transverse

sigmoidal

descending

they lead to the rectum and then the anus

near the stomach, dark, sickle shaped organ to the left of the stomach (the rat's left)

the spleen is an antigen encounter site for white blood cells of the immune system

it's also graveyard for old red blood cells

The pancreas of the rat is a diffuse, granular organ loosely attached to the
caudal part curve of the stomach.

It can be easily confused with fat, but is usually darker, grey or pink compared to the off white to yellow of adipose tissue.

You will find packets of pancreatic tissue bound in
mesentery and stretching from near the pyloric sphincter to near the spleen.

In humans, the pancreas is a more discrete organ. The pancreas has several cell types. Insulin producing cells are involved with carbohydrate metabolism. Other pancreatic cells produce α-amylase to digest starch, proteases including trypsin, chymotrypsin and carboxypeptidase, as well as lipase and phospholipase for the digestion of fats and cell membranes. Insulin is secreted into the blood stream, while digestive enzymes are secreted into the duodenum.

the kidneys: sinple squamous epithelium, simple cubodial epithelium

bladder and uteters: transitional epithelium

dorsal

outside

The thymus is a wedge-shaped lymphoid organ that sits cranial to the heart and is attached to the
trachea.

It is the site of T-cell maturation and is critical to the development of the immune system as a mammal matures.

This organ slowly disappears in adult humans. It is the site of T-cell maturation.

larynx: voice producing

submaxillary salivary glands: saliva producing (saliva enters buccal cavity through ducts under the tongue)

buccal cavity: the mouth

The trachea is the tube from the pharynx to the lungs.

It is stiffened with cartilaginous rings (hyaline
cartilage) and lined with pseudostratified ciliated columnar epithelium.

Connecting to the lungs, it branches into two bronchi, one leading left, the other right. Further branching leads to bronchi, bronchioles, and finally in the lungs alveoli, where oxygen exchange takes place.

In female rats, the uterus is a long V-shaped structure. The right and left horns of this V will be found
near the dorsal wall of the abdominal cavity and often are be hidden by the intestines.

Ova (egg cells)
are produced by meiosis in two ovaries, which are found at the cranial ends of each horn of the uterus.

In Rats, ova are directly released into the uterus, without the fallopian tubes seen in human females. This
long uterine structure allows room for the gestation of 8-12 fetuses.

During birth, the fetuses are
delivered through the vagina or birth canal, which leads from the uterus inside to the outside
environment. The orifice of the vagina will be seen on the outside of the rat cranial to the anus.

Sperm cells are produced by meiosis then haploid mitosis in two testes. The testes are ovoid organs
located in a small sack, a body cavity exterior and caudal to the abdominal cavity, known as the
scrotum.

Sperm are then moved to the epididymis, storage sacks within the scrotum and adjacent to the
testis.

During reproduction muscles in the epididymes move the sperm up the vas defrens or spermatic
chords, into the abdominal cavity, to be mixed with different fluids from the prostate, the vesicular
gland and the coagulating gland to make semen, which is ejaculated through the urethra of male rat’s
penis into the vagina of the female rat during sexual reproduction.

The penis leads from the abdominal
cavity to the outside. The prostate, the vesicular gland and the coagulating gland each have left and right halves lateral to the bladder.