The differentiation of the skin and its appendages. II. Altered development of papillary ridges following neuralectomy

Abstract

In order to test the hypothesis that the nervous system is an important determinant of skin differentiation, deletions of the left lumbosacral dorsal root ganglia (DRGs), the sources of cutaneous afferents to the left hindpaw, were performed on opossum pups at day 1 when hindpaws have just begun to be innervated. At birth, each lumbosacral DRG measures about 200 microns rostrocaudally and a deletion measuring 1 mm would span 4-5 DRGs. Following survival periods of 5-24 days, serial sections through the trunk documented partial left lumbosacral DRG deletion and a variable degree of spinal cord destruction. The blood supply to the trunk and hindpaws was preserved. Bilateral enlargement of residual DRGs was observed and regenerating skin at the site of the deletion was hyperplastic and hyperinnervated. The skin of the plantar pads of the hindpaws was studied following the neuralectomies. Statistically significant differences were observed between the left (experimental) and right (control) hindpaws. The density of innervation of the left hindpaw was reduced compared to the right hindpaw, development of papillary ridges was retarded by 3-4 days, and non-innervated Merkel cells were hypogranulated. This period of delay in ridge development is probably a reflection of the expansion of residual DRGs into the peripheral domains of deleted DRGs. The present study confirms a role for afferent nerves in the timing of cutaneous differentiation and a mutual trophic dependence between cutaneous nerves and Merkel cells in the epidermis.

Neurotrophin‐3 signaling in mammalian Merkel cell development

“…Mammalian Merkel cells differentiate in the absence of nerve contact (English et al, 1980;Pasche et al, 1990;Narisawa and Hashimoto, 1991;Morohunfola et al 1992;reviewed by Saxod, 1996). In contrast, their postnatal survival in hairy skin is dependent upon continued contact with nerve fibers (English et al 1980;Nurse and Diamond, 1984).…”

The differentiation of the skin and its appendages. I. Normal development of papillary ridges

“…The present and companion study (Morohunfola et al, 1992) were undertaken in a n effort to test the hypothesis that afferent nerves have a role in controlling the differentiation of the epidermis. The first paper describes the normal development of papillary ridges in the volar pads.…”

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

“…Then they move and spreads at the top of fingers are the sites of papillary ridge development 2,3 . Papillary ridge formation is preceded by four events: mesenchyme condensation, epidermal proliferation, skin innervation, and Merkel cell differentiation 4,5 . The epidermal-dermal fit establishes the unique patterns of ridges and grooves (dermatoglyphs) present on the surface of the plantar and palmar epidermis.…”