The skin and hair of the southern elephant seal, Mirounga leonina (Linn.). IV. Annual cycle of pelage follicle activity and moult

2012 ◽  
Vol 60 (4) ◽  
pp. 259 ◽  
Author(s):  
John K. Ling
Keyword(s):  
Hair Growth ◽  
Growth Cycle ◽  
Elephant Seal ◽  
Hair Follicles ◽  
Southern Elephant Seal ◽  
Growth Stages ◽  
Adult Males ◽  
Mirounga Leonina ◽  
Complete Replacement ◽  
Adult Females

Hair growth stages, anagen, catagen and telogen, were diagnosed histologically in skin samples taken at Macquarie Island from 103 southern elephant seals – 11 pups, 56 immatures, 23 adult females and 13 adult males – in order to correlate hair follicle activity with field observations of this species’ unusual type of moult. The duration of the hair growth cycle in fully developed follicles is ~12 weeks. Hair follicles are active for 2–3 months before, during and after the moult haul-out and are resting at other times of the year. A high proportion of adult females appear to commence hair growth between 4 January and 2 February. While implantation of the blastocyst may be triggered by some astral event, such as daylength, it does not depend on completion of the moult, as suggested by previous authors. The pelage cycle is possibly controlled by an endogenous rhythm established during follicle development and subsequent growth and shedding of the natal coat, but the timing and duration of the moult haul-out may depend on the nutritional status of seals within each particular age–sex class. In adult seals this will be governed by terrestrial activities that involve fasting during the breeding and moulting seasons, whereas immature seals haul out and fast, not only to moult but some also come ashore and rest during winter. There may also be metabolic demands for materials for the complete replacement of the pelage, and much of the stratum corneum.

A histochemical examination of the epidermis of the southern elephant seal (Mirounga leonina L.) during the telogen stage of hair growth

1968 ◽  
Vol 16 (1) ◽  
pp. 17 ◽  
Author(s):  
RIC Spearman
Keyword(s):  
Hair Growth ◽  
Outer Part ◽  
Elephant Seal ◽  
Basal Part ◽  
Southern Elephant Seal ◽  
Horny Layer ◽  
Mirounga Leonina ◽  
Disulphide Bonds ◽  
Sulphydryl Groups ◽  
Hair Shafts

The epidermal horny layer in the elephant seal, Mirounga leonina, is formed of dead, flattened, solidly keratinized cells without basophilic nuclear remnants. The basal part is more compacted than the outer part which is loosely arranged and has wide dorsoventral intercellular spaces, but the cornified cells appear firmly stuck together along their lateral junctions. Sloughing of the horny layer at the end of a season's growth appears to take place without the development of a specialized fission zone. This is in contrast to the sloughing mechanism in lizards and snakes. Keratin disulphide bonds are uniformly distributed in the horny layer but bound sulphydryl groups, calcium, and phospholipids are more concentrated in the basal part. At the telogen hair growth stage the epidermal horny layer was found to be closely united with the hair shafts within the insunken follicle necks. In these regions the compact junctional horny layer reacted for disulphide bonds, bound sulphydryl groups, phospholipids, and calcium. These substances also occurred in the hook-like keratinized cells which attached the resting club hair to the base of the follicle, but the hair keratin itself only reacted strongly for disulphide bonds. The possible significance of bound phospholipid in the horny layer in waterproofing the skin is discussed.

The skin and hair of the southern elephant seal, (Mirounga Leonina (L.) II. pre-natal and early post-natal development and moulting

1967 ◽  
Vol 15 (2) ◽  
pp. 349 ◽  
Author(s):  
JK Ling ◽  
CDB Thomas
Keyword(s):  
Cellular Proliferation ◽  
Elephant Seal ◽  
Hair Follicles ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
Adult Type ◽  
Root Sheath ◽  
Stratum Lucidum ◽  
Near Term ◽  
Post Implantation

The embryological development of hair follicles and the emergence and growth of the foetal pelage of the southern elephant seal, Mirounga leonina (L.), are described in terms of 10 recognizable stages. Follicle primordia appear at a post-implantation age of about 8 weeks and growth of the first definitive hairs takes approximately 14 weeks. Sebaceous glands develop after the sweat gland anlagen, but their ontogeny is more rapid and they function earlier in the formation of the hair canals. The latter are formed by epidermal cellular accretion from without and sebaceous cellular activity within the developing pilosebaceous unit. Development of three epidermal layers is also described and the absence of a stratum granulosum and stratum lucidum noted. The formation of muscle, collagen, and elastic fibres, and blood vessels in the dermis has been observed and described. The histological development of the first adult-type hair generation has been followed in near-term foetuses and young pups until the latter go to sea. The post-natal moult usually commences about 1 week after birth and takes 3 weeks for its completion. Whereas the foetal hairs are not connected to the stratum corneum lining the pilary canal, with a result that they are shed individually, the epidermis and all subsequent hair generations are united. This union is established after the post-natal moult at the end of the active follicular phase by a process of epidermal and external root sheath cellular proliferation around the bottom of the hair canal.

Physiological implications of continuous, prolonged, and deep dives of the southern elephant seal (Mirounga leonina)

1992 ◽  
Vol 70 (2) ◽  
pp. 370-379 ◽  
Author(s):  
Mark A. Hindell ◽  
David J. Slip ◽  
Harry R. Burton ◽  
Michael M. Bryden
Keyword(s):  
Resting Metabolic Rate ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Adult Males ◽  
Mirounga Leonina ◽  
Physiological Mechanisms ◽  
Elephant Seals ◽  
Aerobic Dive Limit ◽  
Southern Elephant Seals ◽  
Extended Surface

The diving behaviour of 14 adult southern elephant seals was investigated using time depth recorders. Each of the seals performed some dives that were longer than its theoretical aerobic dive limit. Forty-four percent of all dives made by post-moult females exceeded the calculated limit compared with 7% of those made by postbreeding females and less than 1% of those made by adult males. The extended dives displayed characteristics that suggested that they were predominantly foraging dives, although some were apparently rest dives. Dives longer than the calculated aerobic limits often occurred in bouts; the longest consisted of 63 consecutive dives and lasted 2 days. Postmoult females performed longer bouts of extended dives than postbreeding females. Extended surface periods (longer than 30 min) were not related to the occurrence of extended dives or bouts of extended dives. The possible physiological mechanisms that permit such prolonged continuous dives are discussed. Southern elephant seals may increase the aerobic capacity of dives by lowering their metabolism to approximately 40% of the resting metabolic rate on long dives. There is substantial interseal variability in the methods used to cope with long dives. Some animals appear to use physiological strategies that allow them to prolong the time available to them at the bottom of a dive, while others use alternative strategies that may limit the time available at the bottom of their dives.

Population status and seasonal haulout patterns of the southern elephant seal (Mirounga leonina) at Heard Island

1999 ◽  
Vol 11 (1) ◽  
pp. 38-47 ◽  
Author(s):  
David J. Slip ◽  
Harry R. Burton
Keyword(s):  
Total Population ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
Population Status ◽  
Elephant Seals ◽  
Adult Females ◽  
Seal Population ◽  
Heard Island ◽  
One Year

We surveyed the southern elephant seal population at Heard Island regularly from February 1992 to March 1993, and determined the haulout patterns of the major components of the population. While haulout patterns of moulting and immature seals may give broad indices of population trends, the breeding haulout of adult females was the only reliable haulout that could be used to determine annual pup production. During the breeding season 14 277 adult females were counted. Raw counts were corrected using two models, one purely mathematical and the other based on the haulout behaviour of adult female seals. The two models have slightly different assumptions, but both provided good fits to the observed haulout patterns and estimated total population with a coefficient of variation of less than 5%. Total pup production was estimated at between 17 000 and 18 000 for 1992. Previous counts of elephant seals from 1949–51, 1985 and 1987 were corrected using the same models. The two models gave estimates of the population that were within ± 2.5% for all but one year. The population declined by about 50% between 1949 and 1985 but there appears to have been little change from 1985–92. The previous decline may be related to changes in sea-ice.

The skin and hair of the Southern Elephant Seal Mirounga leonina (L.) III. morphology of the adult integument

1968 ◽  
Vol 16 (4) ◽  
pp. 629 ◽  
Author(s):  
JK Ling
Keyword(s):  
Stratum Corneum ◽  
Elephant Seal ◽  
Hair Follicles ◽  
Southern Elephant Seal ◽  
Histological Structure ◽  
Mirounga Leonina ◽  
Root Sheath ◽  
Stratum Spinosum ◽  
Interfollicular Epidermis ◽  
Sheath Cells

The histological structure and certain histochemical features of the skin, hair follicles, and associated glands have been studied in 57 male and 49 female elephant seals. The epidermis comprises only three layers, stratum germinativum, stratum spinosum, and stratum corneum. The absence of granular and clear layers leads to a parakeratotic condition of the horny layer which is made up of large cornified sheets joined to lateral strands of the pelage hairs. Although pigment abounds in the interfollicular epidermis, it does not extend into the external root sheath cells of the hair follicles. There are no arrector pili muscles attached to the pelage hair follicles which are simple, unbranched, and contain only one fully developed lanceolate hair. Hairs are firmly anchored in their follicles by means of lateral filaments insinuated between external root sheath cells. A single, small, apocrine-type sweat gland opens into the hair canal below the common duct of the large, bilobed, sebaceous gland on the ental side of the follicle. The lipid-rich sebum is secreted within the lamellae of the stratum corneum and its function appears to be the maintenance of the outer horny layers in a pliable and perhaps water-resistant condition. The walls of the sebaceous duct are replete with glycogen. The dermis comprises a network of collagenous fibres and a decreasing number of elastic fibres in aging seals, as well as histiocytes and dermal fat cells. Problems of thermoregulation arising from loss of hair in seals exemplified by M. leonina and compensatory features apparent in the morphology of the skin and hair are discussed.

scholarly journals Transcriptome Dynamics Reveal Stage-Specific and Melatonin-Triggered Gene Expression Patterns During The Cashmere Growth Cycle in Capra Hircus

2021 ◽  
Author(s):  
Chun Li ◽  
Cong Feng ◽  
Guangyuan Ma ◽  
Shaoyin Fu ◽  
Ming Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Signaling Pathways ◽  
Expression Patterns ◽  
Growth Cycle ◽  
Hair Follicles ◽  
Receptor Interaction ◽  
Morphological Evidence ◽  
Gene Expression Patterns ◽  
Growth Stages ◽  
Nf Kappa B

Abstract Background Cashmere goat is famous for its high-quality fibers. The growth of cashmere in secondary hair follicles exhibits a seasonal pattern arising from circannual changes in the natural photoperiod. Although several studies have compared and analyzed the differences in gene expression between different cashmere growth stages, the selection of samples in these studies relies on research experience or morphological evidence. Distinguishing cashmere growth cycle according to gene expression patterns may help to explore the regulation mechanisms related to cashmere growth and the effect of melatonin from a molecular level more accurately. Results In this study, we applied RNA-sequencing to the hair follicles of three normal and three melatonin-treated Inner Mongolian cashmere goats sampled every month during a whole cashmere growth cycle. A total of 3559 and 988 genes were subjected as seasonal changing genes (SCGs) in the control and treated groups, respectively. The SCGs in the normal group are divided into three clusters, and their specific expression patterns help to group the cashmere growth cycle into anagen, catagen and telogen stages. Some canonical pathways such as Wnt, TGF-beta and Hippo signaling pathways are detected as promoting the cashmere growth, while Cell adhesion molecules (CAMs), Cytokine-cytokine receptor interaction, Jak-STAT, Fc epsilon RI, NOD-like receptor, Rap1, PI3K-Akt, cAMP, NF-kappa B and many immune-related pathways are detected in the catagen and telogen stages. The PI3K-Akt signaling, ECM-receptor interaction and Focal adhesion are found in the transition stage between telogen to anagen, which may serve as candidate biomarkers for telogen-anagen regeneration. Pairwise comparisons between the control and melatonin-treated groups also indicate 941 monthly differentially expressed genes (monthly DEGs). These monthly DEGs are mainly distributed from April and September, which reveal a potential signal pathway map regulating the anagen stage triggered by melatonin. Enrichment analysis shows that Wnt, Hedgehog, ECM, Chemokines and NF-kappa B signaling pathways may be involved in the regulation of non-quiescence and secondary shedding under the influence of melatonin. Conclusions Our study decodes the key regulators of the whole cashmere growth cycle, laying the foundation for the control of cashmere growth and improvement of cashmere yield.

Disorders of Hair

2013 ◽  
Author(s):  
James Q Del Rosso
Keyword(s):  
Hair Loss ◽  
Alopecia Areata ◽  
Hair Growth ◽  
Growth Cycle ◽  
Hair Follicles ◽  
Common Type ◽  
Diagnosis And Treatment ◽  
Basic Knowledge ◽  
Androgenetic Alopecia ◽  
Broad Overview

A basic knowledge of the hair growth cycle is needed to evaluate disorders of hair growth. This chapter presents a broad overview of the physiology and evaluation of hair growth, as well as discussions of specific types of alopecia. The epidemiology, pathogenesis, diagnosis, and treatment of androgenetic alopecia, the most common type of nonscarring hair loss, are covered. Diffuse hair shedding is generalized hair loss over the entire scalp. Diagnosis and treatment of telogen effluvium, anagen arrest (anagen effluvium), and other causes of diffuse hair shedding are covered in detail. Alopecia areata, typically characterized by patchy hair loss; cicatricial alopecia, which results from permanent scarring of the hair follicles; and miscellaneous causes of hair loss are also discussed. Tables list the causes of diffuse and cicatricial alopecia, telogen effluvium, and miscellaneous chemicals and categories of drugs that can cause alopecia, as well as miscellaneous causes of hair loss. Included is an algorithm outlining the approach to diagnosing nonscarring alopecia, as well as a variety of clinical photographs. This review contains 9 highly rendered figures, 6 tables, and 42 references.

scholarly journals The northernmost haulout site of South American sea lions and fur seals in the western South Atlantic

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Natália Procksch ◽  
M. Florencia Grandi ◽  
Paulo Henrique Ott ◽  
Karina Groch ◽  
Paulo A. C. Flores ◽  
...  
Keyword(s):  
Mixed Model ◽  
Linear Mixed Model ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
South American ◽  
Mirounga Leonina ◽  
Sea Lions ◽  
Significant Difference ◽  
Northern Portion ◽  
Kernel Density Analysis

AbstractWe present estimates of the seasonal and spatial occupation by pinnipeds of the Wildlife Refuge of Ilha dos Lobos (WRIL), based on aerial photographic censuses. Twenty aerial photographic censuses were analysed between July 2010 and November 2018. To assess monthly differences in the numbers of pinnipeds in the WRIL we used a Generalized Linear Mixed Model. Spatial analysis was carried out using Kernel density analysis of the pinnipeds on a grid plotted along the WRIL. Subadult male South American sea lions (Otaria flavescens) were the most abundant pinniped in the WRIL. Potential females of this species were also recorded during half of the census. The maximum number of pinnipeds observed in the WRIL was 304 in September 2018, including an unexpected individual southern elephant seal (Mirounga leonina), and a high number of South American fur seal yearlings (Arctocephalus australis). However, there was no statistically significant difference in counts between months. In all months analysed, pinnipeds were most often found concentrated in the northern portion of the island, with the highest abundances reported in September. This study confirms the importance of the WRIL as a haulout site for pinnipeds in Brazil, recommends that land research and recreational activities occur in months when no pinnipeds are present, and encourages a regulated marine mammal-based tourism during winter and spring months.

Sign in / Sign up

Export Citation Format

Share Document