The early embryogenesis of papillary (sweat duct) ridges in primate glabrous skin: The dermatotopic map of cutaneous mechanoreceptors and dermatoglyphics

Abstract

The present study documents the early innervation of the epidermis prior to the onset of differentiation of the papillary (sweat duct) ridge in glabrous digital skin of rhesus monkey embryos measuring 45, 50 and 55 mm (crown-rump) length. We observed small papillary ridges, spaced at a distance of approximately 40 microns, projecting into the dermis in the center of the distal glabrous digital pad of digits 2-5 in the 55-mm embryo. The other digital pads lacked any sign of ridge formation. A two-dimensional, approximately hexagonal grid of afferent nerves was present in the superficial dermis of all digital and palmar pads. At regular intervals of approximately 40 microns, afferent nerves ascended from the superficial dermal nerve plexus and innervated the overlying epidermis. By electron microscopy, axonal growth cones were identified contacting Merkel cells that projected several microns down into the superficial dermis in the digital pad of digit 3. Thus, the earliest wave of differentiated dorsal root ganglion neuroblasts innervates Merkel cells. Schwann cells partially encircled these growing axon tips and could be identified by the presence of rough endoplasmic reticulum and free ribosomes. The youngest embryo studied had no sign of ridge formation; however, axons ascended from the superficial dermal nerve net at 30-40-microns intervals to innervate the epidermis. We conclude that afferent nerve fibers provide a two-dimensional grid that could modulate the spacing and arrangement of the papillary or sweat duct ridges of successive digits. Such an interaction is possible between digits based on the overlapping dermatotopic maps of each rete ridge. An abnormal fingerprint could thus reflect abnormal dorsal root ganglion neuroblasts expressed through mesenchyme and epidermis.

Relationship between Palmar Dermatoglyphic Pattern and Academic Performance of Students in a Ghanaian Secondary School

“…Distorted presentations of the human body on the cortical areas are said to correlate with peripheral innervation density. Thus the hand and the fingers have high innervation density that is said to determine the dermatoglyphic characteristics of individual (Dell and Munger, 1986).…”

“…(ii) the brain and epidermal ridge (or papillary peaks) patterns on fingers (fingerprints) and palms (palmprints) develop at the same period from embryonic ectoderm (Hirsch and Schweighel, 1973). (iii) the hand and the fingers have high brain innervation density that is said to determine the dermatoglyphic characteristics of individual (Dell and Munger, 1986). (iv) individuals with a simian or single transverse palmar crease, Sydney crease have delayed development, learning difficulties and/or behavioural disorders (Johnson and Opitz, 1971;Bagga, 1991).…”

Prenatal sex hormone effects on child and adult sex-typed behavior: methods and findings

“…These findings and associated indirect evidence about fetal development, e.g. regarding the role of homeobox genes in development of urogenital system and digits (as described above), the common endoderm derivatives of skin and nervous system [266], and the role of testosterone in stimulating production of epidermal and nerve growth factors [267,268], have led to the suggestion that dermatoglyphics can serve as a window into prenatal development.…”

An Original Histological Method for Studying the Volar Skin of the Fetal Hands and Feet

“…They were recently reviewed by 26 the dermatoglyph can reflect the ontogeny of the afferent nervous system that occurred prior to papillary ridge development. Afferent nerve fibers provide a two-dimensional grid that could modulate the spacing and arrangement of the papillary and sweat duct ridges of successive digits 24 . Bonnevie 17 also suggested that there is a direct relationship between cutaneous nerve distribution and the location of the centers of ridge patterns.…”

“…• Classical methods of light microscopy 2,3,21 • Methods of scanning electron microscopy 22,23 • Methods of transmission electron microscopy 24 • Methods of immunohistochemistry (for identify structures of afferent nerves and Merkel cells) 25,26 212…”