fetus

 

The fetus

The. before is called prenatal. That is when the oven rose by step by step into a full form baby e by the the end of 40 weeks of gestation prenatal it.period is divided into  3 stages

germinal period

germinal ovular period this is the time which last from ovulation to 2 weeks in spite of fact that the ovum is fertilized till the completion of these two weeks it is called as ovum nutrition is supplied by the means of of absorption from tubal and uterine secretions that is required very little after the nutrition stored in cytoplasm. Its weight is around 1 gram looks like curd Bean

Embryonic stage

It begins at the fifth week ok of Mensuration or third week after ovulation by this time limp buds appear the nutrition is obtained from eroded decidua by diffusion and later from maternal blood that is stagnant

Roughly formed body structure with weight upto 4g length measuring around 3 cm

Fetal stage

  it starts at 10th week of menstruation or 8 week following ovulation and ends delivery. Embryo can be e recognised as human can measures about 4 cm that's the reason why chronology Li in fetus period is expressed in terms of menstrual age institute of embryonic age

To calculate age of M length is more reliable criteria then age of the fetus

Nutrition is with the established fetus circulation the Peters takes what it needs from Mother even at the cost of of reducing her resources

At the age of 8 weeks weight is around 4 grams head is large hands and feet are are recognisable

At the age of 12 weeks weight is around 60 grams height is approximately 9 CM placenta is well formed at this stage fingers and toes of the features are formed

By the age of 16 intrauterine weeks gestation fetus weighs about 180 grams its height is around 15 CM Plus nasal septum and palate fuse external genitalia is formed movement of fetus occurs

20 weeks of gestational age shows all body parts formed hair on head and eyebrows appear nail scene fetus heart sounds are audible ll and mother can feel the fetus movements

As the fetus reaches the intrauterine age of 22 weeks it is about 30.5 weight is approximately 700 grams with the large head and wrinkled skin covered with vernix

The end of 28 weight is 1200 g height is about 35.5 CM and at 32 weeks weight of the fetus reaches 1700 g and height is about 40.5 born at this stage expert care is required that is new natural ICU with the 50% chance of survival

When fetus reaches gestational age of 36 weeks weight is around 2500 g height is about 45 CM this is the stage height and weight changes totally formed born between the age of 36 to 40 weeks it is able to survive weasel as well as parietal organs are well developed posterior fontanelle are closed nails project beyond fingertip

Systems of foetus

The fetal circulatory system

Umbilical vein carries oxygenated blood from the placenta enter the fetal umbilicus and runs through falciform ligament of liver it gets mixed with portal venous deoxygenated blood through ductus venosus to enter the inferior Vena cava and after that to the right Atrium of the the heart where the most of blood is supplied to the foramen ovale remaining 25% of blood in the right Atrium passes through the tricuspid opening into the right ventricle

Respiratory system

At 28 weeks of gestation alveoli expand before which the lungs are solid surfactant is the substance that is secreted by the type to alveoli that releases surface tension of the lung fluid so that the alveoli can be opened easily when breathing establishes just after the delivery

Gastrointestinal system

By 16th week of gestation foetus start soloing amniotic fluid myconian that is composed of wind from the waste from the hepatic secretion lenugo epithelial cells which are swallowed with the amniotic fluid are distributed uniformly through the gut greenish black colour is due to bile pigmentation

Skin

Sebaceous glands appear at the age of 20 weeks of gestation lanugo(tan colourless hair) appear at 16 weeks and disappear almost completely at vernix caseosa abundantly present smearing the skin which almost disappears till the age of 40 weeks of gestation

Endocrine system

At 10th week hormones produced by fetal pituitary are growth hormones, growth hormones united tropic hormone prolactin a c t h fetal adrenal shows hypertrophy where oesterol is hormone produced fetal pancreas start secrete insulin from 12th week of intrauterine age

Urinary system by the end of first trimester of pregnancy fetal nephrons are active to secrete urine near term foetus producers around 650 ml of urine per day kidney are not essential for survival of foetus in utero but important in regulation of volume and composition of amniotic fluid

Fetal blood

It is demonstrated in embryonic phase liver becomes major site by the 10th week gradually red blood cells extend to the spleen and bone marrow baby's haemoglobin is about 22 gram per cent atom leukocytes appear after 2 months of gestation