Author/Editor     Petrovič, Danijel
Title     Normalen razvoj človeškega zarodka in nepravilnosti v njegovem razvoju
Translated title     Normal development and abnormalities in the development of human embryo
Type     članek
Source     Med Razgl
Vol. and No.     Letnik 42, št. 2
Publication year     2003
Volume     str. 183-201
Language     slo
Abstract     Human embryology is the science dealing with the development of the embryo and fetus from fertilization to birth. Development begins with fertilization, the process by which the male gamete, the sperm, and the female gamete, the oocyte, unite to give rise to a zygote. The zygote undergoes a series of mitotic divisions, increasing the number of cells; a 16-to-32-cell morula is formed, which is transformed into a blastocyst. The blastocyst has two parts, the inner cell mass or embryo proper, and the outer cell mass or trophoblast (future placenta). Teratology is the science dealing with congenital malformations. Approximately 2 to 3% of all living newborns show at least one recognizable congenital malformation. During a certain critical period during pregnancy, embryos are more susceptible to agents or factors causing abnormal development than at other times. Damage to the embryo during the first 3 weeks of embryogenesis (the early period, before the onset of organogenesis) is unlikely to result in defective development, because it either kills the embryo or is compensated for by the powerful regulatory properties of the early embryo. The period of maximal susceptibility to abnormal development occurs between weeks 3 and 8, when most of the major organs and bodily regions are first established.
Summary     Embriologija je veda, ki proučuje razvoj zarodka oziroma ploda od oploditve do rojstva. Ob oploditvi nastane z združitvijo moške spolne celice (spermija) z žensko spolno celico zigota, iz zigote pa morula (16- do 32-celični štadij) in blastocista. Blastocisto tvorita dva dela, notranja skupina celic in zunanji ovoj ali trofoblast (del bodoče posteljice). Teratologija je veda, ki se ukvarja s prirojenimi nepravilnostmi (kongenitalne malformacije). Pogostnost prirojenih nepravilnosti ocenjujemo na 2 do 3% vseh živorojenih novorojencev. Zarodek (plod) je v različnih obdobjih različno občutljiv na dejavnike okolja, ki lahko povzročijo prirojene nepravilnosti. Poškodbe v prvih 3 tednih razvoja zarodka (zgodnje obdobje pred organogenezo) so največkrat smrtne, zarodek umre, in le redko povzročijo prirojene nepravilnosti. Obdobje največje občutljivosti zarodka na zunanje dejavnike je od 3. do 8. tedna razvoja, ko se razvije večina organov.
Descriptors     FETAL DEVELOPMENT
BLASTOCYST
PREGNANCY, ECTOPIC
TROPHOBLAST
GASTRULA
PLACENTA
FETAL MEMBRANES
UMBILICAL CORD
AMNIOTIC FLUID
TWINS
ABNORMALITIES