The oral stage is the initial phase of Sigmund Freud's theory of psychosexual development, occurring from birth to approximately 12 to 18 months. During this period, the infant's mouth serves as the primary source of pleasure, with actions such as sucking, chewing, biting, and drinking playing a crucial role in reducing tension. These activities are essential not only for nourishment but also for the infant's psychological and emotional satisfaction.
Weaning, typically occurring...

Sigmund Freud's theory of psychosexual development describes the anal stage as occurring between 18 months and three years of age. During this period, children derive pleasure from controlling and releasing their bowel movements. However, they quickly learn that societal expectations impose restrictions on when and where this can happen. This stage marks a critical point where children begin to develop a sense of control and mastery over their bodily functions, as well as their broader...

The third stage of psychosexual development proposed by Freud is the phallic stage, occurring between the ages of 3 and 6. During this period, children become aware of their bodies and the differences between males and females. The erogenous zone in this stage is the genitals, and conflicts arise as children develop desires toward the opposite-sex parent. Boys experience the Oedipus complex, where they desire their mother and view their father as a rival. This leads to castration anxiety, the...

Following the phallic stage in Freud's theory of psychosexual development, children enter a phase called the latency period, which lasts from approximately six to twelve years of age. Unlike earlier stages, where sexual impulses played a central role, Freud believed these impulses are repressed during the latency period, becoming part of the unconscious. This stage is often described as a time of psychological calm after the turbulence of the phallic stage.
The latency period is not...

The genital stage is the final phase of Sigmund Freud's theory of psychosexual development, beginning at puberty, around age 12. During this stage, sexual energy shifts from self-focused interests to external individuals, marking the development of mature adult sexuality. Freud saw this phase as a time of sexual reawakening, with desires directed toward others outside the family. A healthy transition into this stage, according to Freud, signifies the emergence of two key aspects of adult...

Rous Sarcoma virus or RSV was discovered by F. Peyton Rous in the year 1911 as a filterable transmissible agent that could cause tumors in chickens. He won a Nobel Prize for this discovery in 1966. His experiments clearly demonstrated that some cancers could be caused by infectious agents and led to the discovery of many more cancer-causing viruses in animals as well as humans.
RSV is a retrovirus that contains two copies of a plus-strand  RNA genome. Its genome consists of four main open...