Lec.13 DEV'T OF IMMUNE SYSTEM Flashcards
The adult body employs multiple layers of defense against foreign materials.
These defenses are derived from all ____.
____, comprising of intact epithelia (i.e. the skin and gastrointestinal tract) serve as a first layer of defense and are derived from the ectoderm and endoderm, respectively.
three embryonic germ layers
Physical barriers
Cells of the second and third layers of defense, the ____ and ____ systems, are derived from the mesoderm.
innate (pre-existing) immunity
specific (induced/acquired) immunity
*Lymphocytes
Differentiation of lymphocytes begins in the ____ as early as during the hepato-lienal period.
____ develops, followed by the appearance of lymph nodes, tonsils, and the spleen.
thymus
Gut-associated lymphoid tissue
*Lymphocytes
In the medullary period, the bone marrow becomes a site of both hematopoiesis, including lymphopoiesis, and lymphocyte differentiation.
The bone marrow, the thymus, and also the gut-associated lymphoid tissue comprise the ____, in which cells of the lymphoid cell lineage differentiate and mature.
primary lymphoid tissues
*Lymphocytes
Lymphoid cell lineage can be divided as:
large lymphocytes with a granular cytoplasm - ____
small lymphocytes with almost no cytoplasm - ____
natural killer cells
B and T lymphocytes
*T Lymphocytes
A small population of common ____ will begin to stay at the Thymus during fetal development.
T lymphocytes mediate cellular immune response to foreign macromolecules either: ____ (by killing virus-infected cells), ____ (activation of specialized phagocytes like macrophages)
hematopoietic stem cells
directly
indirectly
*T Lymphocytes
In the thymus, ____ proliferate, mature and form different type of T cells.
During maturation in the thymus, clones of T lymphocytes differentiate into either:
____
____
progenitor T lymphocytes
Helper T cells (Th cells)
Cytotoxic T cells (Tc cells)
*B Lymphocytes
In many species, B lymphocyte development and maturation takes place in the ____.
In the sheep, the major site for these processes appears to be in an ____.
In birds, another site of development is the ____.
Bone marrow
ileal Peyer’s patch
Bursa of Fabricius
*B Lymphocytes
B lymphocytes mediate a humoral immune response through their differentiation into antibody-producing plasma cells.
The antibodies bind to set areas on foreign macromolecules (antigens) known as ____.
epitopes
*Lymphoid Organs
Organs that regulate the initial development and maturation of lymphocytes are called ____.
Some examples include: bone marrow, thymus, bursa of Fabricius and Peyer’s patches.
primary lymphoid organs
*Lymphoid Organs
The thymus forms around:
Day __ of gestation in ruminants
Day __ in carnivores
Day __ in horse
The thymic reticulum develops from the ventral endodermal part of the third pharyngeal pouches.
Day 40 of gestation in ruminants
Day 30 in carnivores
Day 60 in horse
*Lymphoid Organs
Eventually, the thymus is infiltrated of ____ of hematopoietic stem cell origin.
T lymphocytes will migrate into the deeper portions of the thymus for maturation, and eventually into the blood stream.
T lymphocyte precursors
*Lymphoid Organs
Pre-natally, at least in the sheep, an ileal Peyer’s patch exists and is regarded as the primary lymphoid organ for _____ maturation.
The bursa of Fabricius in birds functions the same as the Peyer’s patches.
In domestic species other than the sheep, the bone marrow is to be regarded as the _____.
B lymphocyte
primary lymphoid tissue
*Lymphatics
The lymphatic vasculature develops in parallel with the ____ but more slowly.
Whereas the blood vasculature forms a continuous loop, with arteries and veins connected through capillaries, the lymphatic system is an open-ended, one-way transit system.
blood vasculature
*Lymphatics
The lymphatic vasculature consists of ____, that finally drains into the venous circulation through the jugular vein or the cranial vena cava.
The ____ are secondary lymphoid organs, and serve as local filters in the lymph stream as it makes its way towards the blood circulation.
tissue capillaries, collecting vessels and ducts
lymph nodes
