The umbilical cord is the lifeline between the foetus and placenta. It is formed by the fifth week of development and it functions throughout pregnancy to protect the vessels that travel between the foetus and the placenta. In the present study, 60 term placenta were studied. Out of these 28 were of female and 33 of male babies from healthy looking mothers aged between 25 - 35 years and the parity from one to five. All cords obtained were of normal vaginal deliveries and aborted foetuses. For light microscopy, two cm. of tissue was taken from each cord and fixed in 10% formalin for one week. Grossly the attachments of umbilical cord to the placenta were observed which showed that the eccentric site of insertion was 64.99%, the central insertion 28.33% and the marginal insertion 6.66% from the total observed placenta. The tunica intimae consist of a single continuous wavy layer of small oval or rounded shaped, which bulges into the lumen of arteries. A thick tunica medium which contains two areas of smooth muscle fibres arrange into an inner longitudinal and an outer circular fibres, both being equal in thickness. Between the longitudinal smooth muscles, there are uniformly distributed collagen fibres. In addition there are two to eight folds called Hoboken Folds which cause irregular narrowing of the lumen; some of these folds show bifurcation. Such features of tunica media was observed at nine months umbilical cord section. The Hoboken folds not found at the sections of three and five months of umbilical cord sections. it is concluded that the measurement of thickness of muscular layer (tunica media) increased from 0.6 µm at the third month of gestation to 9.2 µm at ninth month (at delivery) which may be lead to increase the strength and elasticity of the cord against torsion and compression as the foetus became near the delivery time.
Key words: Histology, Umbilical Cord, Different Stages of Gestation
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