Animal Reproduction
Comp 15.00-16.00: Analyze the
male and female parts of the
reproductive tracts.
Animal Reproduction
• Reproduction
– The process by which animals produce
offspring for the purpose of continuing a
– The process begins with…
• The mating of a male and a female of a species
• This is called copulation
Animal Reproduction
• During copulation
– Sperm cells (Spermatazoa) are transferred
from the male reproductive tract to the female
reproductive tract
– In the female reproductive tract, the sperm
unite with the egg cell (ovum) to form an
• The embryo attaches to the uterus where it receives
nourishment, and develops until the new offspring is
delivered from the female reproductive tract in a
process called parturition
Male Macrostructure and Function
• Male Reproductive System
– Major Function
• The production, storage, and deposition of sperm
• Also functions by production male sex hormones
and serves as a passageway for expelling urine
from the urinary bladder
Male Macrostructure and Function
• Testes
– Paired, ovoid shaped organs that produce
sperm cells and the male sex hormone
• Testosterone causes the development of
secondary male characteristics and sex
behavior/drive (libido)
Male Macrostructure and Function
• Scrotum
– Protects and supports the
• The wall of the scrotum
raises or lowers the tests to
maintain a constant
testicular temperature of
approximately 4-6 degrees
below body temperature,
because sperm must
develop under conditions
cooler than the body.
Male Macrostructure and Function
• Epididymis
– Coiled tube connected to each testis and is
responsible for the maturation, storage, and
transportation of sperm cells.
– The deferent duct (vas deferens) originates
from the epididymis and serves as a
passageway for sperm to the urethra
Male Macrostructure and Function
• Accessory glands
– Responsible for the production of secretions
that contribute to the liquid non-cellular
portion of semen, known as the seminal
Male Macrostructure and Function
• Vesicular glands (seminal vesicles)
– Paired accessory glands that secrete seminal
fluid that adds fructose and citric acid to
nourish the sperm and functions as a
protection and transportation medium for
sperm upon ejaculation
• Ejaculation
– Discharge of semen from the penis
Male Macrostructure and Function
• Prostate Gland
– Secretes a thick, milky fluid that mixes with
the seminal fluid and provides nutrition and
substance to the ejaculation.
• Cowper’s Gland (bulbourethral gland)
– Secrete a fluid similar to the seminal fluid,
cleanses and neutralizes the urethra form
urine residue that can kill sperm cells.
Male Macrostructure and Function
• The Penis
– The organ that allows for deposition of semen
into the female reproductive tract.
– The sheath
• The external portion of the male reproductive tract
that serves to protect the penis form injury and
Male Microstructure and Function
• Spermatogenesis
– Is a process of cell division and maturations
that begins with stationary cells called
spermatogonium and ends with motile
Male Microstructure and Function
• Seminiferous Tubules
– Are tubular structures that coil through the
– The process of spermatogenesis takes place
within the seminiferous tubules.
Male Microstructure and Function
• Interstitial Cells
– Between the seminiferous tubules are groups
of interstitial cells (cells of Leydig) that
function in the production of the male sex
hormone, testosterone.
Male Microstructure and Function
• Testosterone
– Is an androgen hormone that directs the
development of masculine traits
– A constant level of androgens, especially
testosterone, has a major influence on an
animal’s libido, as well as spermatogenesis
Female Macrostructure and
• The purpose of the female reproductive
– Is to produce the eggs (ova) to be fertilized by
the sperm
– Also serves as a receptacle for the penis
during copulation
– Houses and nourishes the fetus until
Female Macrostructure and
• Ovaries
– Two ovaries function to produce eggs and the
female hormones, estrogen and progesterone
• Oviducts (fallopian tubes)
– Are the paired tubes that transport the eggs form
the ovaries to the uterus
• Two funnel-like opening called infundibulums
– Pick up the eggs at ovulation and direct them to the oviducts
• The oviduct is the site where the sperm and th ova meet
and where fertilization occurs
Female Macrostructure and
• Uterus
– The uterus consists of a body and horns
• The embryo attaches to the uterine body, or to the
wall of the uterine horn, depending on the species
of the animal
– Functions as the passageway for sperm
during copulation
– Incubates the embryo during pregnancy, and
contacts to expel the fetus during parturition
Female Macrostructure and
• Vagina
– The vagina serves as the receptacle for the
penis during copulation and as the birth canal
during parturition
• The uterus is separated form the vagina by the
• The cervix serves as a passageway for the semen
from the vagina to the uterus at copulation
Female Macrostructure and
• Vulva
– Is the external portion of the female
reproductive tract that serves to protect the
internal system from infection, to initially
receive the penis at copulation, and to act as
a passageway for urine.
Female Microstructure and
• Just as the male testes produce sperm cells, the
female ovaries produce ova in the process
called oogenesis
– The development of the ova begins before the female
is even born
– Cells called oogonia develop in the ovaries of a fetus
– By the time of birth, these oogonia have matured into
oocytes. There are thousands of oocytes at the time
of birth; however, only a small portion of these
develop into ova or reach ovulation
Female Microstructure and
• Follicle
– The process of oogenesis occurs within a
follicle. Either on a continual cycle or
seasonally, females of different livestock
species will produce ova through the process
of oogenesis.
Female Microstructure and
• Corpus Luteum
– After ovulation, the ruptured
follicle collapses and a small
hemorrhage occurs
• this blood-clotted area is called a
corpus hemorrhagicum and only
lasts two to three days
• This area begins to be filled by a
yellow mass of cells. This yellow
body is called the corpus luteum.
– Its cells have the primary
purpose of producing the female
sex hormone, progesterone
Female Microstructure and
• The process of oogenesis is a part of the
estrous cycle
– This cycle includes estrus, a period in which a
female shows outward signs of receptivity to
breeding as a result of the hormones
secreted, also referred to as “heat”
Structure of the Male Reproductive
System in Poultry
• The male reproductive anatomy of poultry
differs when compared to that of other
animal species
– The poultry anatomy consists of two testes
(each with an epididymis and vas deferens)
that lead to papillae and a rudimentary
copulatory organ
• Rudimentary Copulatory Organ
– An underdeveloped sex organ such as is found in male
Structure of the Male Reproductive
System in Poultry
• The testes are unique in
that they are located along
the backbone within the
abdominal cavity
• The cloaca is the portion of
the lower end of the avian
digestive tract that provides
a passageway for products
of the urinary, digestive,
and reproductive tracts
Structure of the Male Reproductive
System in Poultry
• The copulatory anatomy
consists of two papillae
and the rudimentary
copulatory organ
– The papillae are located
at the end of the vas
deferens and on the floor
of the cloaca
– During copulation, the
sperm is passed from the
papillae into the oviduct
opening or cloacal wall of
the female
Structure of the Male Reproductive
System in Poultry
• Androgen is the male
sex hormone
produces by the
– It not only directs
sexual activity and the
production of sperm,
but it also controls
secondary sexual
characteristics of the
male including:
growth, crowing or
gobbling, and strutting
Structure of the Female
Reproductive System in Poultry
• The female of most animal species has two
functional ovaries
– Mature female poultry have only one functional
• The functional parts consist of an ovary, an oviduct,
and the cloaca.
• The ovary appears as a cluster of tiny, gray balls
that are oocytes
• At maturity, the ovary contains up to 4,000 tiny
oocytes from which yolks or ova (ovum) may
develop over time.
Structure of the Female
Reproductive System in Poultry
• Each oocyte is enclosed in a thin sac
called the follicle and is attached to the
ovary by a vascular stalk.
– When the yolk is mature it is released form
the follicle and then engulfed by the funnellike infundibulum
Structure of the Female
Reproductive System in Poultry
• The yolk
– Enters a coiled oviduct that is about 25 inches
long and consists of five clearly define parts
• The first part is the infundibulum. The
infundibulum functions in receiving the yolk and is
the site of fertilization
• The second part is the magnum that secretes the
thick white or albumen
• The third, the isthmus adds the two shell
Structure of the Female
Reproductive System in Poultry
• The fourth, the uterus secretes the thin white, the
shell, and the shell pigment.
• Last, is the vagina that holds the egg until it is laid
– The egg passes from the oviduct to the cloaca and then
out of the body through the vent at the time of laying
The Formation of an Egg:
The Yolk: The chicken egg starts as an egg yolk inside a hen. A yolk (called an oocyte at this point) is produced
by the hen's ovary in a process called ovulation. The yolk is the food for the developing embryo
Fertilization: The yolk is released into the oviduct (a long, spiraling tube in the hen's reproductive system), where
it can be fertilized internally (inside the hen) by a sperm.
The Egg White (albumin): The yolk continues down the oviduct (whether or not it is fertilized) and is covered with
a membrane (called the vitelline membrane), structural fibers, and layers of albumin (the egg white). This part of
the oviduct is called the magnus.
The Chalazae: As the egg goes down through the oviduct, it is continually rotating within the spiraling tube. This
movement twists the structural fibers (called the chalazae), which form rope-like strands that anchor the yolk in the
thick egg white. There are two chalazae anchoring each yolk, on opposite ends of the egg.
The Eggshell: The eggshell is deposited around the egg in the lower part of the oviduct of the hen, just before it is
laid. The shell is made of calcite, a crystalline form of calcium carbonate. This entire trip through the oviduct takes
about one day.
Growth of the Embryo: The fertilized blastodisc (now called the blastoderm) grows and becomes the embryo. As
the embryo grows, its primary food source is the yolk. Waste products (like urea) collect in a sack called the
allantois. The exchange of oxygen and carbon dioxide gas occurs through the eggshell; the chorion lines the
inside surface of the egg and is connected to the blood vessels of the embryo.
The Incubation Period: The embryo develops inside the egg for 21 days (the incubation period), until a chick
pecks its way out of its eggshell and is hatched.
Structure of the Female
Reproductive System in Poultry
• Estrogen is the female sex hormone
– In poultry estrogen stimulates the growth of
the oviduct and causes the cloaca to increase
in size during egg laying
• It also modifies the feather shape and
pigmentation of the female
• Estrogen increases the level of fat, phosphorus,
and calcium in the blood, as this is necessary in
egg production
Related flashcards

Kidney diseases

74 cards

Kidney diseases

77 cards


17 cards


64 cards

Create Flashcards