Dermatoglyphics Introduction

In the sixth and seventh week of gestation, pads begin to develop on the palmar aspect of the fingertips, on the palm, in the inter-digital spaces, as well as on the radial (thenar) and ulnar (hypothenar) areas of the proximal palm (Fig. 12.1). These pads derive from mesenchymal cells and contain mucopolysaccharide-protein complexes that can bind water. The pads show great variation in size and symmetry. They influence the pattern of the developing dermal ridges. On the tips of the fingers, large fetal pads develop a whorl pattern, intermediate sized pads a loop pattern, while a smaller flat pad will usually give rise to an arch pattern (Fig. 12.2). During this gestational period, cells proliferating in the stratum germinativum of the epidermis grow down into the dermis and form epidermal ridges, which are established by the 17th gestational week.About that time the mesenchymal pads start to regress. The ridges and grooves form the dermatoglyph-ics on the surface of the palm, fingers, sole of the feet and toes. The permanent dermatoglyphic pattern is set by the 19th week of gestation.

The flexion creases in the skin of the body begin to develop in the second to third gestational month. Those of the limbs are usually present

Figure 12.1 Distribution of pads at 10 weeks gestation. From Martin and Sailer (1962), by permission.

Figure 12.1 Distribution of pads at 10 weeks gestation. From Martin and Sailer (1962), by permission.

Pregnancy And Childbirth

Pregnancy And Childbirth

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