The choroid plexus or plexus choroideus is a part of the human anatomy found on the ventricles of the human brain where the CSF (cerebrospinal fluid) is made by the modified ependyman cells. The choroid plexus can be found in all of the components of the ventricular system except for in the cerebral aqueduct and the frontal and occipital horns of the lateral ventricles. The choroid plexus can be located in the superior section of the inferior horn of the lateral ventricle and follows a pathway up along the boundary and continues with the inferior of the body of the lateral ventricles, from here it passes over into the interventricular foramen and is then present at the top of the third ventricle and there is another on the fourth ventricle on the section located nearest to the bottom half of the cerebellum. The choroid plexus or CP for short is made up of many capillaries which are separated from the ventricles via the choroid epithelial cells. Through these cells there is a liquid which is filtered from blood in order to become cerebrospinal fluid in text files of cna training classes you find more. Active transportation of substances into and out of the cerebral spinal fluid is also present as the CSF is being made. The human brain has in total four choroid plexus with one for each of the four ventricles. The plexus consist of a layer of cuboidal epithelial cells which surround a core of capillaries and loose connective tissue and the epithelial layer of the plexus is a continuous one with the ependymal cell layer which lines the ventricles.

Unlike the ependyma, the choroid plexus eipithelial layer has tighter junctions located in between the cells on the side which are facing the apical surface (ventricle). These junctions act as a preventative for the most of the substances from making a cross from the cell layer over into the cerebralspinal fluid and therefore act as a blood-CSF barrier. The choroid plexus also acts as a filtration system by removing the metabolic waste as well as foreign substances and excess neurotransmitters from the cerebral spinal fluid. These actions which are performed everyday in the human anatomy by the Choroid Plexus make it a very important part of the human body with it fulfilling vital roles in assisting in maintaining the delicate extracellular environment and atmosphere that is an essential requirement of the human brain in order for the brain to have the ability to function at the optimal level.

During the developmental stage of embryological growth, some fetuses may form what are known as choroid plexus cysts. These cysts are fluid filled and detected with a level 2 ultrasound at around 18 – 20 weeks gestation. Finding these cysts is relatively a common occurrence and the typically disappear during the later stages of the pregnancy and are generally considered to be soft markers. It is considered that these cysts are likely to be harmless with no effects seen on infants or the early childhood development of children who were observed to have choroid plexus cysts in the womb.