Sclera in lobe-finned fishes, various reptiles, and birds. The ring has disappeared in many groups, including living amphibians, some reptiles and fish, and all mammals. The eyes of all non-human primates are dark with small, barely visible sclera. The collagen of the sclera is continuous with the cornea. From outer to innermost, the four layers of the sclera are: The sclera is opaque due to the irregularity of the Type I collagen fibers, as opposed to the near-uniform thickness and parallel arrangement of the corneal collagen. Moreover, the cornea bears more mucopolysaccharide (a carbohydrate that has among its repeating units a
Sociology of the body Sociology of the body Sociology of the body is a branch of sociology studying the representations and social uses of the human body in modern societies. According to Thomas Laqueur, prior to the eighteenth century the predominant model for a social understanding of the body was the "one sex model/one flesh model". It followed that there was one model of the body which differed between the sexes and races, for example, the vagina was simply seen as a weaker version of the penis and even thought to emit sperm. This was changed by the Enlightenment. In the sixteenth century, Europe