Diphallia, penile duplication (PD), diphallic terata, or diphallasparatus, is an extremely rare developmental abnormality in which a male is born with two penises. The first reported case was by Johannes Jacob Wecker in 1609. Its occurrence is 1 in 5.5 million boys in the United States.When diphallia is present, it is usually accompanied by renal, vertebral, hindgut, anorectal or other congenital anomalies. There is also a higher risk of spina bifida. Infants born with PD and its related conditions have a higher death rate from various infections associated with their more complex renal or colorectal systems. It is thought diphallia occurs in the fetus between the 23rd and 25th days of gestation when an injury, chemical stress, or malfunctioning homeobox genes hamper proper function of the caudal cell mass of the fetal mesoderm as the urogenital sinus separates from the genital tubercle and rectum to form the penis. The first case was reported by Wecker in Bologna, Italy, in 1609, and since then, about one hundred cases have been reported. This condition has existed in humans since ancient times. The two external genitalia may vary in size and shape, either lying beside each other in a sagittal plane or one above the other in a frontal plane.According to Schneider classification in 1928, double penis is classified into three groups: (a) glans diphallia, (b) bifid diphallia and (c) complete diphallia or double penis.
The hippocampus deals largely with memory consolidation, where information from the working memory and short-term memory is encoded into long-term storage for future retrieval. Amnesic patients with damage to the hippocampus are able to demonstrate some degree of unimpaired semantic memory, despite a loss of episodic memory, due to spared parahippocampal cortex. In other words, retrograde amnesics "know" about information or skill, but cannot "remember" how they do. The diencephalon and the surrounding areas role in memory is not well understood. However, this structure appears to be involved in episodic memory recall. The temporal lobes are essential for semantic and factual memory processing. Aside from helping to consolidate memory with the hippocampus, the temporal lobes are extremely important for semantic memory. Damage to this region of the brain can result in the impaired organization and categorization of verbal material, disturbance of language comprehension, and impaired long-term memory. The right frontal lobe is critical for the retrieval of episodic information, while the left frontal region is more active for the retrieval of semantic information. [56] Lesions in the right hemisphere and right frontal lobes result in the impaired recall of non-verbal material, such as music and drawings. Difficulties in studying this region of the brain extends to its duties in comprehension, naming objects, verbal memory, and other language functions.Brain plasticity has helped explain the recovery process of brain damage induced retrograde amnesia, where neuro-structures use different neural pathways to avoid the damaged areas while still performing their tasks.