The composition of female rat skin in relation to region, age, hair growth cycle and hormones

Skin from the dorsal flank of rats had a higher water content, a lower fat content per unit dry weight, and a higher hydroxyproline content, estimated as a proportion of the dry, defatted skin weight, than skin from the ventral flank.

In each region the water content decreased with age until the rats were about 80 days old and then remained relatively constant; the hydroxyproline content increased with age between 25 and 150 days, but not in a regular manner. There were no significant changes in skin fat with age in either region.

Superimposed on these changes were cyclic fluctuations which were correlated with the hair growth cycle. The water content was greatest during the latter part of the resting phase, and fell steeply during early activity of the follicles to a minimum towards the middle or in the latter part of the active phase. Fat reached a peak around the middle of the active phase and fell to a trough during the resting phase; it started to increase again well before the start of new follicular activity. Hydroxyproline fell during the early active phase to a minimum shortly after eruption of the hair, and then rose to reach a new peak in early telogen.

When the follicular period was shortened by ovariectomy or administration of thyroxine, or lengthened by implantation of oestradiol or by inhibition of the thyroid with propylthiouracil, the changes in water, fat and hydroxyproline continued, in the main, to fluctuate in phase with follicular activity, and the regional differences were substantially maintained. There was a tendency for the fluctuations to be accentuated when the periods were shortened and damped when they were lengthened.

Oestradiol accelerated the fall in skin water content which normally occurs with age, so that the ultimate low plain was achieved 25 days earlier. In propylthiouracil-treated rats the skin water content decreased more slowly than in normal rats, and had not reached a stable value by 150 days of age. Oestradiol-treated rats had more and spayed rats less skin fat at any age than normal controls. The skin fat content rose progressively when rats were treated with propylthiouracil.

Effect of an anabolic steroid upon various fractions of tissue hydroxyproline in cortisone treated rats

Anabolic steroid methandrostenolone was tested for its ability to protect the rats against cortisone-induced changes in chemistry of collagen. Extractive chemical study of dermal and hepatic collagen was performed in controls, cortisone treated and in cortisone plus methandrostenolone treated rats. Significant decrease of saline-extractable, insoluble and total hydroxyproline and significant increase of acid-extractable hydroxyproline was found in cortisone treated rats. Most of the fractions of hydroxyproline were found normal in rats treated with both steroids. Protective action of an anabolic steroid against cortisone-induced collagen alterations was demonstrated in this experiment.

Detection of histamine by a new fluorescent omicron-phthalaldehyde stain

A simple, rapid technique has been developed for the visualization of histamine in its cellular depots throughout the body. Based on the yellow fluorochrome formed by the interaction of o-phthalaldehyde and histamine, this procedure permits direct fluorescence microscopy of the "histaminocytes." Study of fresh blood and tissues from man and many animals revealed histamine its the mast cells, blood vessels, gastric mucosa, and in some species, platelets.

The chemical nature and evolutionary significance of monogenean attachment sclerites

The chemical and physical nature of monogenean attachment sclerites has been investigated by chromatography, histochemistry, solubility studies and X-ray diffraction, and these sclerites have been shown to be scleroproteinaceous and not, as the bulk of the literature suggests, chitinous in composition.

Hooks sclerites (i.e. marginal hooks and hamuli), which are the most primitive type of monogenean attachment sclerites and arise early on ontogeny, have been shown to be keratinous; clamp sclerites, accessory bars and the spines arming the pseudohaptors and squamodisks of certain genera which appear to have been acquired later in the phylogeny of the group to supplement the efficiency of the haptoral hooks, contain no cystine sulphur.

While the chemical nature of the non-cystine-containing skeletal structures has not been fully elucidated, clamp substance was found to differ from that of the other scleroproteins with which it was compared, namely sclerotin, vertebrate elastin, reticulin, collagen and keratin. Clamp substance does not appear to be quinonetanned; acid proteins maybe important in the stabilization of this scleroprotein.

Evidence for the occurrence of a variety of S–S bearing scleroproteins throughout the invertebrates has been collated and the problems involved in adequately defining a keratin have been discussed. The implications of the apparent affinity of monogenean hook protein to vertebrate keratins, which in general are intracellular and epidermal derivatives have been considered and some speculations have been made about the possible differences in the development of hook and clamp structures.

Contrary to the prevalent opinion that monogenean sclerites are ‘cuticularizations’, evidence has been presented that these structures are in fact deeply seated and unlikely to be derivations of a superficial cuticle.

The chemical differences elucidated between the median and lateral sclerites of the chimaericolid adhesive organ have encouraged speculation on the evolution of the different types of attachment organ throughout the polyopisthocotylineans.

Outside the Monogenea, studies on the sulphur content of digenean spines and stylets and on the larval hooklets of the ‘cestodarians’Gyrocotyle, AmphilinaandArchigetes, and of eucestodes, have helped to substantiate the view that the cestodes and monogeneans are more closely related to each other than either of these groups is related to the digeneans.

I wish to thank the Director and staff of the Plymouth Laboratory and in particular Mr J. E. Green, for invaluable assistance. I am also indebted to Dr R. W. H. Small for his guidance on X-ray diffraction technique, to Dr J. Morris of the M.R.C. Skin Unit for his advice on the chromatography and to Dr J. Llewellyn for his interest and helpful criticism throughout.

The structure and chemical composition of the nematode cuticle. Observations on some oxyurids and Ascaris

Studies of the cuticle ofAspiculuris tetrapterawith both the light and the electron microscopes have shown that there are three basic layers, namely the cortex, which consists of an outer and an inner layer, the matrix layer and the fibre layer; the latter is made up of three layers. There is, in addition, a thin osmiophilic superficial membrane on the surface of the cuticle; this membrane is seen only with the electron microscope.

It is shown that the major structural protein of the cuticle, although showing no axial periodicity, is collagen; the collagen is associated with hyaluronic-acid- and chondroitin-sulphate-containing mucopolysaccharides.

Evidence is presented for the existence of two centres of protein synthesis (collagen fibrogenesis) in the cuticle ofA. tetraptera, Syphacia obvelataandAscaris lumbricoides.These centres are located in the inner cortex and the hypodermis. The cuticle is thus very active metabolically.

I wish to acknowledge with thanks the facilities afforded me at the Molteno Institute during the course of these studies by the Director, Dr P. Tate. My thanks are also due to Dr D. L. Lee for his encouragement and helpful discussions during the investigations.