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Animal physiology 214 notes on the male reproductive system
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Animal physiology 214 notes on the female reproductive system
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REPRODUCTIVE SYSTEMSMALE REPORDUCTIVE SYSTEM
— Males produce a vast number of sperm in contrast to females who produce comparatively few
eggs.
— Many sperm attach to the ovum, but typically only one tunnels through the zona pellucida and
actually fertilizes the ovum.
— Sperm integrity depends on all three sections (head, midpiece, and tail) of the sperm structure
being in full working order.
Zona pellucida = barrier surrounding ovum
Ovum = mature egg, produced by female. An immature ovum is an oocyte
Development of reproductive system
— Foetal development
— Post-natal development
Foetal development
— Foetal development of males involves the presence of the SRY gene in the embryo, which
stimulates the production of testis-determining factor, or TDF. This TDF stimulates the formation of
testes and differentiates the embryo into a male. Lack of the SRY gene (which is found only on the Y
chromosome) will mean that no TDF is produced, and the embryo will develop into a female.
— All embryos contain both the Wolffian duct system and the Mullerian duct system. In male
embryos, the Wolffian duct system develops into the male reproductive system and the Mullerian
duct system recedes. Conversely, in female embryos the Mullerian duct system develops into the
female reproductive tract and the Wolffian duct system will recede.
— All the components for a fully functional reproductive system are established during foetal
development. These components lie dormant until the body reaches puberty.
Post-natal development
— This begins when animals reach puberty. The onset of puberty is determined by weight and is
initiated once an animal has reached a certain body mass. By managing the animal’s weight, we can
cause the puberty to start earlier, resulting in animals becoming sexually mature at a younger age.
This can be very advantageous for production.
— Secondary sexual characteristics are the visible changes which accompany sexual maturity. For
example, males will typically become more muscular, especially in the forequarters. A lion’s mane is
another example of a secondary sexual characteristic.
— Behavioural changes also occur such as aggression, territorial behaviour, and interest in females.
— Sperm production is initiated during puberty but communication between the hypothalamus,
pituitary glad and testes is not yet synchronized, so hormones are imbalanced.
, — Since certain hormones are too low, the sperm produced are not really viable yet, and lack full
motility. This means that even if an immature male still undergoing puberty were to mate, the
chances of fertilization occurring is low.
— Sexual maturity is reached at the end of puberty. The hypothalamus, pituitary, and testes will be
synchronized; the hormone levels would have stabilized; and the sperm should now be fully viable.
It is important to understand how different animals will mature sexually as it is often necessary to select
breeding animals before they are mature. A good knowledge of the animals will allow you to manage them
correctly when it comes to breeding, environment, selection, etc.
Anatomy:
— Testes
— Epididymis
— Scrotum
— Vas deferens
— Accessory glands
Testes:
— Sperm is produced in the testes.
Production of sperm is called
Spermatogenesis.
— Location of testes differ according to animal species. Many animals such as bulls have pendular
testes which are suspended outside the abdominal cavity. Some animals such as elephants have
retroperitoneal testes which are located inside the abdominal cavity.
— The testes secrete testicular fluid which helps to move the sperm along to the epididymis.
— This movement is achieved through peristalsis of the smooth muscles surrounding the ducts of the
testes.
Thermoregulation of testes is very important as the proteins involves in sperm production are heat
sensitive. The arterial blood flowing into the testes is much warmed than the venous blood leaving the
testes. The heat difference is evened out in the pampiniform complex which cools the arterial blood by 4-6
degrees.
Another method of thermoregulation in some animals involves pulling the testes closer to the body during
cold conditions. Under warm conditions, the testes are suspended further away from the body and the
scrotum can contain sweat glands to assist in cooling. The cremaster muscle controls the retraction of the
testes.
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