Anomalies and monsters

DISTURBANCES IN DEVEOPMENT
(ANOMALIES & MONSTER)
  • Anomaly is developmental defect affecting an organ or part of the body.
  • Anomaly is the disturbance of development that involves an organ or a portion of an organ.
  • Monster is an animal in which extensive abnormal developments are present.
  • A Congenital disease is one in which the patient is born with the disease whereas an inherited disease is one which is due to factors in the genetic materials received from the parents.

CLASSIFICATION OF ANOMALIES

A. Arrest of Development

1. Agenesia is an incomplete and imperfect development of an organ or part and aplasia is absence of an organ or part.

  • Acrania is absence of most or all of the bones of the cranium.
  • Amelia is absence of one or more limbs.
  • Anencephalia is absence of the brain.
  • Hypocephalia is incomplete development of the brain.
  • Hemicrania is absence of half of the head.
  • Exencephalia is defective skull with brain exposed or extruded. If the protruding brain contains a ventricle which is filled with excessive amount of fluid, the malformation is a hydrencephalocele.
  • Arhinencephalia is absence or rudimentary development of the olfactory lobe with corresponding lack of development of the external olfactory organs.
  • Agnathia is absence of the lower jaw.
  • Anophthalmia is absence of one or both eyes.
  • Abrachia is absence of the forelimbs.
  • Abrachiocephalia is absence of forelimbs and head.
  • Adactylia is absence of digits.

2. Fissures on the median line of the head, thorax, and abdomen.

  • Craniooschisis (skull)
  • Cheiloschisis (lip), often referred to as harelip.
  • Palatoschisis (oral) cavity, often called cleft palate. Harelip and cleft palate result from faulty development of the maxillary process derived from the first visceral arch.
  • Rachischisis (spinal column).
  • Schistorrachis or spina bifida (spinal column)
  • Schistothorax (thoraz or sternum).
  • Schistosomus (abdomen).
  • Schistocormus (thorax, neck or abdominal wall). Results from arrested development of the amnion.

Anomalies-Palatoschisis

Palatoschisis

3. Fusion of paired organs

  • Cyclopia (eyes)
  • Ren arcuatus (kidneys), often referred to as horseshoe kidney.

B. Excess of Development

1. Congenital hypertrophy

  • Hemi hypertrophy (partial)

2. Increase in the number of a part

  • Polyotia (ears)
  • Polyodontia(teeth)
  • Polymelia (limbs)
  • Polydactylia(digits)
  • Polymastia (mammary gland)
  • Polythelia(teats)

DISPLACEMENTS DURING DEVEOPMENT

A. Displacements of organs

  • Dextrocardia is transposition of the heart to the right side.
  • Ectopia cordis cervicalis is displacement of the heart into the neck.

B. Displacements of tissues

  • Teratoma is inclusion of multiple displaced and also neoplastic tissue within an individual.
  • Dermoid is inclusion within an individual of a mass containing skin, hair, feathers, or teeth depending on the species and often arranged as an epidermal cyst (Dermoid cyst).
  • Odontoid cyst is inclusion within an individual of a mass of dental enamel and cement.
  • Dentigerous cyst is inclusion within an individual of one or more imperfectly formed teeth.
  • Fusion of Sexual Characters
  • Hermaphrodite is an individual having both testicular and ovarian tissue. Pseudohermaphrodite is an animal having unisexual development of the sex glands (either testicular or ovarian tissue), but having also either a unisexual or bisexual development of the other parts of the genitalia.
  • Freemartin is a female calf having arrested development of the sex organs and being the twin of perfect male.

MONSTERS

A monster or monstrosity is a disturbance of development that involves several organs and causes great distortion of the individual. For the most part monsters possess a duplication of all or most of the organs and other parts of the body. They develop from a single ovum. They are therefore the product of incomplete twinning.

Classification of the Monsters

  • Twins Entirely Separate
    • Although separate, these twins are in a single chorion. One twin as a rule is well developed; the other is malformed (acardius). In the malformed foetus there is arrested development of the heart, lungs, and trunk. Such monsters may lack a head (acephalus), limbs and other recognizable features (amorphous), or the trunk (acormus).
  • Twins United
    • These twins are more or less completely united and are of symmetrical development.

TWINS UNITED

A. Anterior Twinning: The anterior part of the individual is double, the posterior single.

  • Pygopagus – united in the pelvic region with the bodies side by side.
  • Ischiopagus – united in the pelvic region with the bodies at an obtuse (not pointed) angle.
  • Dicephalus – two separate heads; doubling may also affect the neck, thorax and trunk.
  • Diproosopus – doubling in the cephalic region without complete separation of heads; only the face doubled.

B. Posterior Twinning: The posterior part is double, the anterior single.

  • Craniopagus – brains usually separated; bodies as a rule at an acute angle.
  • Cephalothoracopagus – union of head and thorax.
  • Dipygus – doubling of posterior extremities and posterior part of body.

C. Twinning Almost Complete: Duplication of the whole trunk or the anterior or posterior extremities with parallel, ventral arrangement of the foetuses. The pair is joined in the region of the thorax, and also often in the abdominal region.

  • Thoracopagus – united only by the thorax.
  • Prosopothoracopagus – besides the union the thorax the abdomen, the head and neck are united.
  • Rachipagus – thorax and lumbar portion of the spinal column united.
Last modified: Wednesday, 7 December 2011, 5:20 AM