Animal Tissue and Anatomy

The central portion of the stem is filled with parenchyma cells that have very distinct intercellular spaces; this region is collectively known as the pith.

The male genital pore in pheretima is located in 18^th segment.

It is the inner lining of an anther.

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The bladder is located on the floor of the pelvic cavity. The bladder is located anterior to (i.e. in front of) the rectum in males. In females, it is also in front of the uterus and upper vagina, so its location is described simply as anterior to the uterus and upper vagina.

The innermost layer of the wall of the urinary bladder is the mucous membrane (also called the mucosa), which contains transitional epithelium tissue that can stretch. The ability of this tissue to stretch is important because it contains variable volumes of liquid - as the bladder is filled and emptied several times per day. Because it is only loosely attached to the (strong and substantial) muscular layer, the mucosa falls into many folds known as rugae when the bladder is empty or is only filled to a small extent.

Kidneys are bean-shaped organs, each about the size of a fist. They are located near the middle of the back, just below the rib cage, one on each side of the spine. The kidneys are sophisticated reprocessing machines. Every day, a person's kidneys process about 200 quarts of blood to sift out about 2 quarts of waste products and extra water.

The renal capsule is the membranous covering of the kidney. It directly covers the renal cortex, which forms the outer stratum

The cortex of the kidney is the outer section which covers the internal medulla. The cortex is visible near the outer edge of the cross-sectioned kidney. It is composed of blood vessels and urine tubes and is supported by a fibrous matrix.

The renal column or Bertin column, or column of Bertini is a medullary extension of the renal cortex in between the renal pyramids of the kidney. It allows the cortex to be better anchored. Each column consists of lines of blood vessels and urinary tubes and a fibrous material.

The vagina is a muscular passage which forms a part of the female sex organs and which connects the neck of the uterus (called the cervix) with the external genitals. The vagina, which is approximately two and one-half to four inches long, has muscular walls which are supplied with numerous blood vessels.

The clitoris is covered by a fold of skin, called the prepuce, which is similar to the foreskin at the end of the penis. Like the penis, the clitoris is very sensitive to stimulation and can become erect. These are the external structures of the female reproductive system.