The 2nd Semester of 2019 -2020 Academic Year in Nantong University, Supplementary Exam of

Histology and Embryology

Ⅰ. Review and Question ( 100 points in total, 10 points each) Score Reviewer

1. In what regions of the body would you expect to find hyaline cartilage, fibrocartilage, and elastic
cartilage, and why would these supporting connective tissues be located in these regions?

Cartilage is a connective tissue structure that is composed of a collagen and

proteoglycan-rich matrix and two cell types: the chondrocyte and the
chondroblasts.

There are three types of cartilage:

 Hyaline cartilage (glassy cartilage)

 the most widespread type of cartilage in the body,

particularly in the fetus and infant.

 thin collagenous fibril of type II collagen

Distribution:

Much of the fetal skeleton consists of cartilage

In the adult, hyaline cartilage persists in the larynx, trachea, bronchi, ribs, and on the articular
surface of bones.

Fibrocartilage

 Fibrocartilage has characteristics intermediate

 between hyaline cartilage and dense connective tissue.
 large amount of parallel collagen fibers (type I)
 cartilage cells are in a line, small and less, surrounded with a bit of purple matrix, the
rest of the tissue is dense connective tissue.
 It is found in
 the intervertebral disks
 the symphysis pubis
 the articular discs of the sternoclavicular and temperomandibular joints
 the menisci of the knee joint
  Elastic cartilage

 large amount of elastic fibers

 Elastic cartilage is found in
 the external ear
 the walls of the external, auditory canal, (the Eustachian tube)
 the epiglottis

2. When blood is centrifuged, a thin, gray-white layer called the buffy coat covers the layer of packed
erythrocytes. What are the components of the buffy coat?

 Blood is a red fluid (fluid CT) (specific gravity of 1.052-1.064).

Constitutes about 7% of our total body weight

 The lowermost layer (45% of the blood volume) consists of erythrocytes.

 Above this region is a grayish white layer (buffy coat) which represents the platelets,
lymphocytes and granulocytes (about 1-2% volume).

 The uppermost layer is the plasma

A buffy coat suspension is a concentrated leukocyte suspension. It contains

most of the white blood cells and platelets from a whole blood sample.
3. How does the myelin sheath differ between the CNS and the PNS?

Myelin is present in the central nervous system (CNS) and peripheral nervous
system (PNS); however only the central nervous system is affected by MS.
CNS myelin is produced by special cells called oligodendrocytes. PNS myelin
is produced by Schwann cells. The two types of myelin are chemically
different, but they both perform the same function — to promote efficient
transmission of a nerve impulse along the axon.

MNF in CNS

Structure:

similar to in PNS

 myelin-sheath formed by flattened ending of oligodendrocyte’s processes

 one oligodendrocyte can envelop many axons

 no incisure and basement membrane

① MNF in PNS

LM:

 Axon

 Myelin-sheath:

HE: net-liked;

OsO4(osmium tetroside) fixation and stain: black with

Schmidt-Lantermann incisure

 Neurilemma: cell membrane of Schwann and basement membrane

 Ranvier node: narrow part, no myelin-sheath-saltatory conduction

 Internode: the segment of NF between two Ranvier nodes

4. What is the main function of capillaries? What are the three kinds of capillaries and describe the
structure of each capillary.

• Fuction: Capillaries: the smallest blood vessels, constituting a complex network of thin tubules.
Through the walls, the interchange between blood and tissues takes place.

Structure : A single layer of endothelial cells, Basal lamina, A few connective tissue (pericytes)

Types:

 Continuous capillary : distributed in muscle tissue, CT, exocrine glands, and nervous tissue.

 endothelial cell: large number of pinocytotic vesicles, no pores

 basal lamina : continuous

 transport macromolecules by pinocytotic vesicles

 Fenestrated capillary: distributed in the kidney, intestine, and endocrine glands

 endothelial cells: present abundant pores (fenestrae), have diaphragms on them(renel

glomerulus no diaphragm )

 basal lamina : continuous

 macromolecules can pass through by the pores

 Sinusoid : distributed in liver, bone marrow and spleen

 a greatly enlarged diameter

 endothelial cell: intercellular clefts are large between cells, many pores without diaphragm

 basal lamina : discontinuous or in absence

 5. Compare and contrast the red and white pulp of the spleen with respect to the anatomy and
functions of each

Structure:

 Capsule: DCT, containing smooth muscle, is covered by mesothelium

 Trabeculae (artery and vein)
 Parenchyma(white pulp, red pulp)

White pulp: periarterial lymphatic sheath: T, lymphatic nodules (splenic nodules): B, marginal zone

Red pulp: marginal zone, splenic cord

 . 6. What seven hormones are released by the anterior pituitary, what target organs do they affect, and
what are the functions of these hormones?

hormones are chemical messengers secreted into blood that modify the
physiology of target cells.
 Adrenocorticotrophic hormone (ACTH) triggers the adrenals to release the hormone cortisol,
which regulates carbohydrate, fat, and protein metabolism and blood pressure.
This hormone affects the adrenal gland.
 Thyroid-stimulating hormone (TSH)  stimulates thyroid hormone synthesis, storage
and liberation.
This hormone affects the thyroid.
 Luteinising hormone (LH)  stimulate the release of sex hormone
This hormone affets the gonads ( ovaries for women and testes fof men)
 Follicle-stimulating hormone (FSH) stimulate the formation of oocyte and sperm
 and liberation.
This hormone affects the thyroid.
 Luteinising hormone (LH)  stimulate the release of sex hormone
This hormone affets the gonads ( ovaries for women and testes fof men)
 Prolactin (PRL)  stimulates milk production after childbirth
its major target organ is the mammary gland
 Growth hormone (GH)  promote the growth and metabolism of bone
affects growth of bones, muscles and various other organs ( such as liver)
 Melanocyte-stimulating hormone (MSH) regulates the production of melanin, a dark pigment,
by melanocytes in the skin.

It affects Melanin-producing cells ( melanocytes)

7. Explain why the kidneys, heart, GI tract, and gonads are considered part of the endocrine system.

The endocrine system is the collection of glands that produce hormones that regulate
metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and
mood, among other things.

The endocrine system affects almost every organ and cell in the body.
Although the hormones circulate throughout the body, each type of hormone is targeted
toward certain organs and tissues. The endocrine system gets some help from organs
such as the kidney, liver, heart and gonads, which have secondary endocrine functions.

 The kidneys : secretes hormones such as erythropoietin, calcitriol,renin and

prostagrandines. In addition to synthesis , the kidneys also contribute to
the degradation of certain hormones – such as insulin . erythropoietin acts on the bone
marrow to increase the production of red blood cells. Calcitriol acts on the cells
of the intestine to promote the absorption of calcium and phosphate from food
and bone to mobilize calcium from the bone to the blood
 Heart : secretes two peptodes: A-type Natriuretic Peptide and B-type
Natriuretic Peptide (BNP). Both hormones lower blood pressure by relaxing
arterioles, inhibiting the secretion of renin and aldosterone, inhibiting the
reabsorption of sodium ions by the kidneys.
S
 GI tract: ome important hormones are Gastrin, Secretin. Gastric is Secreted
from the stomach and plays an important role in control of gastric acid
secretion. Secretin: Another hormone secreted from small intestinal
epithelial cells; stimulates secretion of a bicarbonate-rich fluids from the
pancreas and liver.
 Gonads: Their main role is the production of steroid hormones.1) The testes
produce androgens, which allow for the development of secondary sex
characteristics and the production of sperm cells. Testosterone, the most
prominent androgen in males, stimulates the development and functioning of the
primary sex organs. 2) The ovaries produce hormones, such as estrogen and
 progesterone, which cause secondary sex characteristics and prepare the body
for childbirth.

8. The GI tract from the esophagus to the anal canal is composed of four tunics. Describe the general
histology of the tunics and the specific features of the stomach tunics.

Mucosa: consists of epithelium of simple columnar, lamina propria composed of areolar tissue
containing small blood vessel and nerves, and muscularis mucosa thin layer of smooth muscle for
contractions.

Submucosa: composed of areolar and dense irregular connective tissue, contains blood vessels,
lymph vessels, and nerves-submucosal nerve plexus-innervates sm. Muscle and glands, houses
mucosa-associated lymphatic tissue (MALT), helps prevent ingested microbes from crossing GI tract
wall, Peyers patches in ileum.

Muscularis: inner circular layer, outer longitudinal layer, myenteric nerve plexus.

Adventitia: composed of areolar connective tissue, found outside the peritoneal cavity. Adventitia is
the outermost layer.

A. Mucosa

 1. Epithelial cells

 2. lamina propria

 3. Muscularis mucosa

B. submucosa: CT, duodenal gland

C. muscularis : thicker

 inner oblique

 middle circular

 outer longitudinal

D. adventitia: serosa
 glomerulus
9. Describe both the anatomic and histology structure of the glomerulus and the visceral layer of the
glomerular capsule.

afferent arteriole (thick)

capillary network

efferent arteriole (thin)

high hydrostatic pressure

glomerular (Bowman’s) capsule

 parietal (external) layer:

simple squamous epithelium

 capsular cavity: filtrate

 visceral (internal) layer:

podocytes
 Podocytes are cells in the Bowman's capsule in the kidneys that wrap around the capillaries of the
glomerulus. The long processes, or "foot projections," of the podocytes wrap around the capillaries, and

podocytes
leave slits

have primary and secondary processes, embrace

the cap
the secondary processes contact the basement
membrane, interdigitating to form the 25nm wid
spaces--filtration slits
diaphragm span the adjacent processes—slit
membrane

10. Describe the implantation of the blastocyst into the uterine wall.