Glossary+Terms

Glossary Terms- illustrations

[|Hip dysplasia] Wayne Riser, Harker Rhodes, and Charles Newton. //Hip Dysplasia Chapter 83//. N.d. Photograph. Textbook of Small Animal OrthopaedicsWeb. 10 Feb 2012. [].

Key terms
[|**Chromosome**] — One of the bodies in the cell nucleus that carries genes. There are normally 46 chromosomes in humans. [|**Cleft lip and palate**] — An opening in the lip, the roof of the mouth (hard palate), or the soft tissue in the back of the mouth (soft palate). [|**Embryo**] — The developing baby from conception to the end of the second month. [|**Fetus**] — In humans, the developing organism from the end of the eighth week to the moment of birth. [|**Gene**] — The The functional unit of heredity that directs all growth and development of an organism. Each human being has more than 100,000 genes that determine hair color, body build, and all other traits. [|**Neural tube defects**] — A group of birth defects that affect the backbone and sometimes the spinal chord. [|**Rubella**] — A mild, highly contagious childhood illness caused by a virus; it is also called German measles. It causes severe birth defects if a pregnant woman is not immune and gets the illness in the first three months of pregnancy. [|**Spina bifida**] — One of the more common birth defects in which the backbone never closes. [|**Trait**] — A distinguishing feature of an individual. [|**Virus**] — A very small organism that causes infection and needs a living cell to reproduce. If both parents carry the same recessive gene, they have a one-in-four chance that the child will inherit the disease. Recessive diseases are severe and may lead to an early [|death]. They include sickle cell anemia, a blood disorder that affects blacks, and [|Tay-Sachs disease], which causes mental retardation in people of eastern European Jewish heritage. Two recessive disorders that affect mostly whites are: [|cystic fibrosis], a lung and digestive disorder, and [|phenylketonuria] (PKU), a metabolic disorder. If only one parent passes along the genes for the disorder, the normal gene received from the other parent will prevent the disease, but the child will be a carrier. Having the gene is not harmful to the carrier, but there is the 25% chance of the genetic disease showing up in the child of two carriers. Some disorders are linked to the sex-determining chromosomes passed along by parents. [|Hemophilia], a condition that prevents blood from clotting, and Duchenne [|muscular dystrophy], which causes muscle weakness, are carried on the X chromosome. Genetic defects also can take place when the egg or sperm are forming if the mother or father passes along some faulty gene material. This is more common in older mothers. The most common defect of this kind is [|Down syndrome], a pattern of mental retardation and physical abnormalities, often including heart defects, caused by inheriting three copies of a chromosome rather than the normal pair. A less understood cause of birth defects results from the interaction of genes from one or both parents plus environmental influences. These defects are thought to include:
 * Cleft lip and palate, which are malformations of the mouth.
 * Clubfoot, ankle or foot deformities.
 * Spina bifida, an open spine caused when the tube that forms the brain and spinal chord does not close properly.
 * Water on the brain ([|hydrocephalus]), which causes brain damage.
 * [|Diabetes mellitus], an abnormality in sugar metabolism that appears later in life.
 * Heart defects.
 * Some forms of cancer.

a coming into being; the act or process of being born. See also [|parturition].
 * birth**

the canal through which the fetus passes in birth; comprising the uterus, cervix, vagina and vulva.
 * birth canal**
 * birth cohort**see [|cohort].
 * birth control**a term rarely used in dealing with animals. Instead see population [|control], [|contraception].
 * birth defects**see [|congenital] defects.
 * birth difficulties**dystocia.
 * birth injury**occurs to the fetus during birth. Includes rib fracture and meningeal hemorrhage.
 * birth interval**the interval between succeeding parturitions. See also [|calving] interval.
 * multiple birth**the birth of two or more offspring produced in the same gestation period.
 * birth order**the chronological order of births in a multiple birth. May have significance in causing stillbirths if the intervals between births are prolonged because of inertia.
 * premature birth**expulsion of the fetus from the uterus before termination of the normal gestation period, but after independent existence has become a possibility. In humans prematurity is defined as a pregnancy of less than 37 weeks in a pregnancy normally lasting 40 weeks.
 * birth process**comprises maturation of the fetus, relaxation of the bony pelvis and associated ligaments, softening and relaxation of the cervix, vagina, vulva and perineum, correct disposition of the fetus, contractions of the uterine myometrium and finally the only component under voluntary control, contraction of the abdominal muscles.
 * birth rate**the number of births during one year for the total population (crude birth rate), for the female population (refined birth rate), or for the female population of reproductive age (true birth rate). Not a term much used with reference to animals. See [|calving], [|lambing] rate.
 * birth size**stature, including height at withers, crown to tail head length at birth.
 * birth weight**the weight at birth. A significant determinant of survival in any species and of the occurrence of dystocia. See also [|prolonged gestation].

Saunders Comprehensive Veterinary Dictionary, 3 ed. © 2007 Elsevier, Inc. All rights reserved []