Agriculture Reference
In-Depth Information
The sensory organ of the skin (the cutaneous sense)
consists of the specifi c sensory cells, which are the recep-
tors, and the sensory nerves whose infl ux reaches the
central nervous system. There the infl ux is transformed in
sensations. There are highly specialized pressure, touch,
pain, cold, and heat receptors.
The hair presents the bulb and the root implanted into
the dermis and the shaft that extends from the surface of
the skin. The invagination of the epidermis and connective
tissue enclosing the root of the hair is called the hair fol-
licle. Some hairs are associated with thin bundles of
muscles, which raise the hair (arrectores pillorum muscles),
and with sebaceous glands. The hair muscles are supplied
by the sympathetic nervous system. The sebaceous glands
located between the base of the tail and the anus produce
a typical waxy secretion. There are different and various
types of hairs, among them, the beard (see Figure 6.40),
which is specifi c to the goat. Accumulation of hair follicles
and sebaceous glands located in skinfolds caudomedial to
the base of the horns are called horn (scent) glands. They
are partially responsible for the characteristic odor of buck
goats in the breeding season. Nevertheless, much smaller
glands are found in female and in castrated male goats.
Interestingly enough, the goat does not possess tactile hairs
on the chin and cheek. The long fi ne wool of the Angora
goat is called mohair, whereas that of the Cashmere goat
is processed into cashmere wool (Frandson et al., 2003).
The tassel (wattle, or cervical appendix) is a symmetri-
cal cutaneous appendage on the latero-ventral surfaces of
the neck, close to the caudal border of the masseter
muscles, and contains a bar of cartilage (see Figure 6.40).
The presence of wattles is controlled by an autosomal-
dominant gene (Pugh, 2002 ).
so- called “ passive immunity. ” Comparable to passive
immunization is the use of colostrum in the fi rst several
days of the neonates. The colostrum contains antibodies
from the mother's immune system. In all mammals, the
lymphatic system (which is part of the cardiovascular
system) is deeply involved in immune reactions. The
lymph nodes, the lymphatic structures in the mucous mem-
branes, thymus, spleen, and bone marrow are the structures
producing antibodies and immune reactions resisting the
action of the antigens. They all contribute to the defense
mechanism of the organism. Those lymphatic structures in
the mucous membranes are located in the pharynx, larynx,
intestine, prepuce, vagina, etc.
The immune system consists of diverse organs produc-
ing different types of antibodies and maintaining the integ-
rity of the body. The lymphocytes, macrophages, and other
“cells” possess immune properties. The thymus and the
bone marrow produce T- and B - lymphocytes, respectively,
which are later produced in the lymph nodes, spleen,
and tonsils. The macrophages belong to the reticulo-
endothelial system (in the reticular connective tissue) and
have the property of phagocytosis (inclusion of the antigen
into their cells and breaking it down) and storage (of
the phagocytized material). For details please consult
topics describing the immunity and the immune system,
such as “ Veterinary Immunology ” by Tizard (2000)
and “ Veterinary Immunology ” by Outteridge (1985) . Even
in the current texts, the caprine immune system is not
addressed directly.
SUMMARY
This chapter, Functional Anatomy of the Goat, was written
as basic knowledge. It covers the essential information to
start with, for any direction the reader will take to pursue
a professional education, to be enrolled in a graduate
school, or to start a research program. The anatomical
structures are described in a systemic and systematic order,
using the international anatomical nomenclature. For
details, different sources of information are suggested.
The 15 sections of this chapter cover the anatomy of the
goat in different proportions, based on the role (functional-
ity) of the anatomical structures. Thus, larger spaces are
attributed to the horn and digital organ; to the cardiovas-
cular, respiratory, digestive, and reproductive systems; to
the sense organs; and to the mammary gland.
The chapter is illustrated with a minimum of original
drawings. Additional fi gures may be seen in the cited lit-
erature (Constantinescu, 2001). The additional suggested
readings are provided for the reader to look for more
details.
THE IMMUNE SYSTEM
The immune system is an intricate complex of cellular,
molecular, and genetic components, strongly interrelated
for providing a defense against foreign organisms or sub-
stances and aberrant native cells (Nickel et al., 1981). The
defense is the so - called “ immune response. ” The foreign
organisms or substances constitute the “antigen,” and the
result of the reaction of the immune system is the produc-
tion of “ antibodies. ” A very specifi c reaction occurs
between the antigen and the antibodies, at the end of which
an “active immunity” is established. Also the active immu-
nity can be obtained by inoculation in a healthy organism
with an attenuated or killed antigen (vaccine). In an indi-
vidual already attacked by an antigen, specifi c antibodies
obtained from a donor (called antiserum) can be inoculated
and can act immediately against the antigen. This is the
