Cecum

The cecum or caecum (/ˈsiːkəm/, plural ceca /ˈsiːkə/; from the Latin caecus meaning blind) is an intraperitoneal pouch, that is considered to be the beginning of the large intestine. It receives chyme from the ileum, and connects to the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve (ICV) or Bauhin's valve. It is also separated from the colon by the cecocolic junction. The appendix is connected to the cecum. While the cecum is usually intraperitoneal, the ascending colon is retroperitoneal.

In herbivores, the cecum stores food material where bacteria are able to break down the cellulose. This function no longer occurs in the human cecum (see appendix), so in humans it is simply a dead-end pouch forming a part of the large intestine.

Structure

Development

The cecum and appendix are formed by the enlargement of the postarterial segment of the midgut loop. The proximal part of the bud grows rapidly to form the cecum. The lateral wall of the cecum grows much more rapidly than the medial wall, with the result that the point of attachment of the appendix comes to lie on the medial side.

Caecum (gastropod)

Caecum is a genus of minute sea snails, marine gastropod micromolluscs or micromollusks in the family Caecidae or blind shells.

Distribution

This genus is distributed worldwide in warm and temperate seas. Many species live in sponges, in sandy spots on reefs, or in grassy beds in shallow waters in bays and lagoons. Some species are very common and can be extremely numerous where they do occur, such as the Beautiful Caecum (Caecum pulchellum), but even they can be easily overlooked as they are so tiny. Many species are considered to be uncommon, but this assessment may be a result of lack of proper sampling.

Shell description

The shells in this genus, like the others in the family,are very small with a length between 2 mm and 6 mm. >Their colour is white to yellowish white and some are almost translucent. They are unusual in that the teleoconch of the adult shell is a curving tube for most of its length. In the first stage of the shell it is spiral-shaped but soon becomes cylindrical. The shell is sealed with a permanent calcareous plug at one end and (when the animal has withdrawn into the shell) with a circular,multispiral, horny operculum at the other end, the shell aperture. The sculpture is smooth or consists of a close-set, large number of annular ridges.