Introduction of Reproductive physiology

Reproduction is essential for continuity of species in living organisms. Asexual & sexual reproduction both produce new individuals.

In mammals reproduction is carried out by union of gametes produced by dimorphic individuals and this increases genetic variability.

Sex is the total morphological, physiological and psychological differences between male and female.

Intersexuality

Freemartin heifer is an intersexual individual and this condition is known as Intersexuality. It is a genetic female which was born as co-twin with a male, leading to modification of female genitalia in the male direction by the masculinizing factors of the male. MIH from the male twin enters the circulatory system of the female twin due to anastomosis of placental blood vessels. The male morphogenic agents from the male twin exert their influence before the development of ovary and Mullerian system in the female twin and the free martin is stimulated to develop male structures.

The gonads resemble testes, Mullerian duct system is inhibited, wolffian ducts remain and differentiate to male duct system.

Freemartins are more common in cattle due to greater degree of placental fusion. It is also reported in sheep, pigs and goats.

Hermaphrodite

The presence of both male and female gonads in one individual animal is known as Hermaphrodite. Female pseudohermaphrodites have normal internal genitalia but intermediate external genitalia. Clitoris may be enlarged or modified to penis.

Male hermaphrodites are common in animals. True hermaphrodites have both ovarian and testicular tissue with intermediate genitalia and are very rare in higher animals.