The complexity of the Sunda porcupine skin has become an important topic due to the unique characteristics of its quill follicles. The structure and chemical composition of the skin has affected many physiological and other conditions. Generally, quills are larger, stronger and stiffer than hair; therefore, the skin structure needs to adapt to support their physiology. The strength of the skin is determined by its collagen composition and arrangement; therefore, this study aims to analyse the composition and distribution of thick and thin fibres based on the specific characteristics of Sunda porcupine skin under polarized light using picrosirius red staining. The skin samples used were from the thoracodorsal and lumbosacral regions of eight Sunda porcupine adults. The histological staining was carried out using the picrosirius red method, while the samples were observed under a polarized light microscope and analysed with software. The results showed that the skin is composed of 36%-65% thick fibres, 20%-35% thin fibres and small amounts of other types with the lumbosacral region having higher compositions of thick and thin fibres than those in the thoracodorsal region. Furthermore, the thoracodorsal and lumbosacral regions have the highest composition of thick fibre in the deeper dermis and quill follicle, respectively. These demonstrated that the complexity of the skin structure of Sunda porcupine due to its quill derivates correlated with its collagen composition and distribution.

Uncoupling protein 1 (UCP-1) was believed to be an exclusive protein found in the brown adipose tissue of small rodents and humans; however, recent studies show that the expression of UCP-1 protein has been found in the sebaceous glands of the mouse tail and human skin. There are a few reports about the presence of UCP-1 in the sebaceous glands of other rodents, such as the Sunda porcupine (Hystrix javanica), a wild spiny rodent commonly found in Indonesia with a large sebaceous gland. The aim of this study was to identify the presence of UCP-1 in the sebaceous glands on the skin of the Sunda porcupine. The skin from three regions (thoracodorsal, lumbosacral and apex caudal) of eight adult Sunda porcupines was used to detect UCP-1-immunopositive cells through immunohistochemistry. All three regions were found immunopositive to anti-UCP-1 antibody in the sebaceous gland of quill and hair follicles, and the epidermal layer in quill and hair follicles with various intensities. The result of immunohistochemistry revealed that the thoracodorsal and apex caudal region was the most intense immunoreaction followed by the lumbosacral region. These findings proved that the presence of UCP-1 was also identified in the sebaceous glands of other rodent (Hystrix javanica) and regions of the body, which has not been reported previously.

Skin becomes the largest organ in the body and protects its own inner layer. The structure and chemical composition of the skin contribute to skin condition and affect the habitat of certain bacteria. The Sunda Porcupine is one of endemic animals of Indonesia which possesses quill as the main derivate of its skin and as a defence tool against predators. The present study used nine adults (five females and four males) of Sunda Porcupine and aimed to observe the correlation of skin structure with bacterial population at the surface level. The skin was wavy due to the protrusion of quill follicle orifices on the skin surface and formed clusters. The skin of Sunda Porcupine was also wrinkled and had a lot of flakiness. Histologically, the skin was composed of epidermis, dermis, hypodermis and subcutaneous muscle. The quill follicles and their properties were the dominant structure component of the skin. No sweat gland was observed in the skin of the Sunda Porcupine, and sebaceous gland was found only around quill and hair follicles. The bacterias identified in the skin were Staphylococcus aureus, S. epidermidis, Micrococcus sp. and Salmonella sp. When compared, the bacterial population was higher in the lumbosacral region than in the thoracodorsal region, but the difference was not significant. The density of quill clusters was negatively correlated to the bacterial population. It was suggested the structure of the skin has contribution to bacterial population in dorsal trunk of the Sunda Porcupine.