Changes

As per modern embryology, susceptibility to teratogenesis depends on the genotype of the conceptus and the manner in which this genetic composition interacts with the environment.  

As per modern embryology, susceptibility to teratogenesis depends on the genotype of the conceptus and the manner in which this genetic composition interacts with the environment.  

The maternal genome is also important with respect to drug metabolism, resistance to infection and other biochemical and molecular processes that affect the conceptus. Susceptibility to teratogens varies with the developmental stage at the time of exposure. The most sensitive period for inducing birth defects is the third to eight weeks of gestation, the period of embryogenesis.

The maternal genome is also important with respect to drug metabolism, resistance to infection and other biochemical and molecular processes that affect the conceptus. Susceptibility to teratogens varies with the developmental stage at the time of exposure. The most sensitive period for inducing birth defects is the third to eight weeks of gestation, the period of embryogenesis. <ref>Prof.Hari Hirdya Awasthi,Dr.Mohd.Ashraf Khan, Garbha sarira, Chaukhambha Orientalia. Varanasi; 1996. First edition.pg.136</ref>

There are three phases of intrauterine growth. Zygote, embryo, and fetus.  

There are three phases of intrauterine growth. Zygote, embryo, and fetus.  

3. The fetal phase / Period III (weeks 9 – 38) further growth and elaboration of the organ systems takes place. During this phase various factors can result in minor or not so severe defects.

3. The fetal phase / Period III (weeks 9 – 38) further growth and elaboration of the organ systems takes place. During this phase various factors can result in minor or not so severe defects.

Birth defects occur due to three main reasons i.e,abnormal formation of tissues, abnormal forces on normal tissues or destruction of normal tissues. Some of these defects may have a cascade effect and result in a group of related anomalies or multiple anomalies (syndromes).  

Birth defects occur due to three main reasons i.e,abnormal formation of tissues, abnormal forces on normal tissues or destruction of normal tissues. Some of these defects may have a cascade effect and result in a group of related anomalies or multiple anomalies (syndromes). <ref>Dhiman K, Kumar A, Dhiman KS. Shad Garbhakara Bhavas vis-a-vis congenital and genetic disorders. Ayu. 2010;31(2):175‐184. doi:10.4103/0974-8520.72384</ref>

Now a day, allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the emerging as a treatment of choice for a variety of congenital disorders.

Now a day, allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the emerging as a treatment of choice for a variety of congenital disorders.<ref>Faraci M, Giardino S, Bagnasco F, et al. Allogeneic hematopoietic stem cell transplantation in congenital disorders: A single-center experience. Pediatr Transplant. 2017;21(6):10.1111/petr.12997. doi:10.1111/petr.12997</ref>

===Abbreviations ===

===Abbreviations ===