The skin structures and their role in the thermoregulation of the South American fur seal (Arctocephalus australis).

The skin of the South American fur seal (Arctocephalus australis) is important for animal thermoregulation in both terrestrial and aquatic environments. Skin tissue samples were collected from A. australis for microscopic analysis and were related to anatomical references. The aim of this study was to describe the skin morphology, as well as to suggest the major anatomical regions and skin components involved in the thermoregulation of this species. Using light microscopy, the skin of six animals was examined based on histological, morphometric, and immunohistochemical criteria. Hair follicle morphology was examined using scanning electron microscopy. The skin was classified as either thick or thin based on its epidermal thickness. The thin epidermis regions had more abundant hair follicles, as well as high pigmentation, whereas the thick epidermis regions had very pigmented epidermal layers. Pigmentation of hair and skin is fundamental for protection against ultraviolet rays; moreover, hair is important in preventing abrasion, and provides an insulating layer against the external environment, which can be much colder than body temperature. Furthermore, the dermis is well vascularized, especially the superficial dermis. All regions of the skin have adaptations for maintaining the animal's condition in both terrestrial and aquatic environments. Among the studied regions, the interdigital region from hindflipper showed important morphological characteristics related to thermoregulation, such as having an epidermis of intermediate thickness, a dermis with a small number of hairs, a large amount of blood vessels, and sweat glands with large lumens, indicating that heat exchange in this region may be faster.

Reproductive Tract Histology in South American Fur Seal Pups (Arctophoca australis).

In the present study, a detailed histological description of the female reproductive tract of South American fur seal (Arctophoca australis) pups has been conducted. The uterine tube was covered by cuboidal to columnar epithelium; nerve fibers were present in the mesosalpinx and beneath the muscular layer. The uterus was bipartitus; the endometrial surface of the horns was lined by a simple cuboidal or columnar epithelium with deep tubular glands; caudally ("the transition area"), the epithelium changed to pseudostratified columnar, few tubular glands were present and the myometrium increased in width. A bistratified epithelium internally coated the uterine body, whereas it changed to cylindrical stratified epithelium with a highly vascularized lamina propria and a strong muscular layer in the cervix; no endometrial glands were observed in this region. From the transition area of the uterus to the vagina there were several nerve fibers and ganglia belonging to the uterovaginalis plexus. In the vestibule, hymenal folds were poorly developed; adnexa structures included the major vestibular glands and a neurovascular structure similar to the vestibular bulb. Minor vestibular glands were associated with the clitoris. The skin of the perineum was lined by a keratinized stratified epithelium, pigmented, with sebaceous glands, sweat glands and hair follicles. This is the first detailed histological description of the reproductive tract of South American fur seal pups, including the glandular adnexa and nerve structures. These results contribute to the reproductive biology in Pinniped species, and give a better understanding of the utero-placental perfusion mechanism during diving. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:600-613, 2017. © 2016 Wiley Periodicals, Inc.

Morphology of the lingual surface of South American fur seal (Arctocephalus australis) and sea lion (Otaria flavescens).

In this study, we aimed to describe the morphological characteristics of the lingual papillae in two species of Otariidae family by stereomicroscopy and scanning electron microscopy. We used tongues of two South American Otariidae species. The tongues were elongated and terminated in bifid apex and there was no median sulcus on the dorsal lingual surface. The most numerous type of lingual papilla was filiform in the South American fur seal (SASL) and entire dorsal lingual surface was covered by these filiform papillae but the dorsal surface of the tongue of the South American sea lion was covered by numerous polygonal projections, which were different in size. Fungiform papillae were detected in only SASL and they randomly distributed on the lingual apex and body, and some fungiform papillae were collected into twosome or threesome groups on the posterior part of the lingual body. Circumvallate papilla was found in the center of the lingual radix of South American sea lion. Thread-like conical papillae were common for both species and they located on the lingual radix. We determined that lingual surface morphology was completely different in each species, although they were members of the same family, Otariidae.

Ovarian follicular morphometry of South American fur seal pups (Arctophoca australis).

The aim of this study was to analyze the morphometric characteristics of ovarian follicles and their distribution in the ovarian cortex in South American fur seal pups (Arctophoca australis). Samples were obtained from animals stranded in the Uruguayan Atlantic coast. Ovaries were dissected, fixed, weighed, and processed by standard histological techniques. Ovarian weight increased with pup age and body length. There was an increase in the diameter of the oocytes (22.24 ± 0.6 to 68.2 ± 5.3 µm), the nuclei (10.04 ± 0.2 to 20.7 ± 1.6 µm), and follicles (30.4 ± 1.2 to 252.6 ± 53.6 µm) of type 1 to type 5 follicles; there was a wide range of variation in the diameter of follicle type 4 and 5. Granulosa layer thickness increased between follicles type 3 and 4, whereas between type 4 and 5 there was a reduction. Thecal layer from follicles type 3 and 4 consisted of 1-2 layers of cells, whereas type 5 showed an increase in thickness (3.13 ± 0.3 to 13.8 ± 5.2 µm). Follicles type 1 and 2 occupied superficial regions within the ovarian cortex while the remaining follicles had a deeper location. These results provide a basis for comparison with females of other age categories as well as follicular dynamics studies in South American fur seals.

Formação do plexo braquial e sistematização dos territórios nervosos em membros torácicos de lobos marinhos / Arctocephalus australis Brachial plexus formation and the nervous territories on thoracic limb of Arctocephalus australis

Para a realização do estudo acerca do plexo braquial (PB) e dos territórios nervosos do membro torácico de lobosmarinhos (Arctocephalus australis) foram utilizados dois animais. A pele foi retirada e procedeu-se a identificação da musculatura do membro torácico e região peitoral. Em seguida foram aplicadas compressas de solução de ácido acético glacial 3% na musculatura, com o intuito de facilitar a dissecação realizada macroscopicamente. Nos espécimes analisados notou-se a emergência do plexo braquial a partir do sexto nervo cervical até o primeiro nervo torácico. Destas quatro raízes se formam os troncos de nervos de mesmo número, cujos ramos ventrais constituirão seu arranjo e distribuição territorial. Destes quatro troncos surgem os 12 nervos componentes do PB, sendo encontrados nervos que se formam a partir de apenas um segmento (supra-escapular, peitoral cranial, torácico lateral, toracodorsal e torácico longo) e também nervos que surgem a partir de mais de um segmento, sendo assim denominados plurissegmentares (subescapular, músculo-cutâneo, axilar, mediano, peitoral caudal, ulnar e radial). Nesse sentido, foi observada uma constância na inervação da musculatura, articulações e ossos do membro torácico, de onde podemos assim inferir que existe um padrão claramente definido na delimitação dos territórios nervosos.

For the study concerning the brachial plexus (BP) and the nervous territories of the thoracic limb of South American Fur Seal (Arctocephalus australis), two animals had been used. Their skin was removed and the musculature of the thoracic limb and pectoral region was identified. After that compresses of glacial acetic acid solution of 3% had been applied in the musculature, in order to facilitate the carried through dissection. In analyzed specimens it was observed the emergency of BP from the sixth cervical nerve until the first thoracic nerve. From these four roots trunks of nerves of the same number are formed, whose ventral branches will constitute its arrangement and territorial distribution. From these four trunks emerge the 12 component nerves of the BP, some of them come from only one segment (supra scapular, cranial pectoral, lateral thoracic, thoraco-dorsal and long thoracic), while others come from more than a segment (sub scapular, muscle-cutaneous, axillary, median, caudal pectoral, ulnar and radial). In this direction,this observed constancy in the innervation of the musculature, joints and bones of the thoracic limb, led us to infer that a definite pattern in the delimitation of the nervous territories clearly exists.

Formação do plexo braquial e sistematização dos territórios nervosos em membros torácicos de lobosmarinhos / Arctocephalus australis Brachial plexus formation and the nervous territories on thoracic limb of Arctocephalus australis

Para a realização do estudo acerca do plexo braquial (PB) e dos territórios nervosos do membro torácico de lobosmarinhos (Arctocephalus australis) foram utilizados dois animais. A pele foi retirada e procedeu-se a identificação da musculatura do membro torácico e região peitoral. Em seguida foram aplicadas compressas de solução de ácido acético glacial 3% na musculatura, com o intuito de facilitar a dissecação realizada macroscopicamente. Nos espécimes analisados notou-se a emergência do plexo braquial a partir do sexto nervo cervical até o primeiro nervo torácico. Destas quatro raízes se formam os troncos de nervos de mesmo número, cujos ramos ventrais constituirão seu arranjo e distribuição territorial. Destes quatro troncos surgem os 12 nervos componentes do PB, sendo encontrados nervos que se formam a partir de apenas um segmento (supra-escapular, peitoral cranial, torácico lateral, toracodorsal e torácico longo) e também nervos que surgem a partir de mais de um segmento, sendo assim denominados plurissegmentares (subescapular, músculo-cutâneo, axilar, mediano, peitoral caudal, ulnar e radial). Nesse sentido, foi observada uma constância na inervação da musculatura, articulações e ossos do membro torácico, de onde podemos assim inferir que existe um padrão claramente definido na delimitação dos territórios nervosos.(AU)

For the study concerning the brachial plexus (BP) and the nervous territories of the thoracic limb of South American Fur Seal (Arctocephalus australis), two animals had been used. Their skin was removed and the musculature of the thoracic limb and pectoral region was identified. After that compresses of glacial acetic acid solution of 3% had been applied in the musculature, in order to facilitate the carried through dissection. In analyzed specimens it was observed the emergency of BP from the sixth cervical nerve until the first thoracic nerve. From these four roots trunks of nerves of the same number are formed, whose ventral branches will constitute its arrangement and territorial distribution. From these four trunks emerge the 12 component nerves of the BP, some of them come from only one segment (supra scapular, cranial pectoral, lateral thoracic, thoraco-dorsal and long thoracic), while others come from more than a segment (sub scapular, muscle-cutaneous, axillary, median, caudal pectoral, ulnar and radial). In this direction,this observed constancy in the innervation of the musculature, joints and bones of the thoracic limb, led us to infer that a definite pattern in the delimitation of the nervous territories clearly exists.(AU)

Histomorphology of prepuberal ovaries in the South American fur seal (Arctocephalus australis Zimmerman, 1783).

The South American fur seal reproductive histophysiology is scarcely described. This study provides a histological description of prepuberal South American fur seal (Arctocephalus australis) ovaries as well as three-dimensional reconstructions of subcapsular crypts and primordial follicles. Ovaries from fresh dead animals were processed for histology and sliced into serial sections. A portion of the superficial cortex was photographed, and the images were processed using BioVis3d software in order to generate 3-dimensional reconstructions. A. australis prepuberal ovaries conform to the basic structure of pinnipedian species, with a subcapsular crypts system made up of interconnecting cisternae and tubules with multiple openings to the surface. Generally, the primordial follicles were arranged in a monolayer beneath the tunica albuginea and were closely associated with subcapsular crypts. The large number of interstitial cells distributed throughout the cortex was the main histological feature in comparison with previous reports in other seals. Three-dimensional reconstructions modelled the subcapsular crypts microarchitecture and showed the close spatial relationship between the crypts and the primordial follicles. Despite the fact that the general ovarian histological structure was similar to that of other pinnipeds, the large number of interstitial cells is a distinctive feature that raises the question about the origin and function in A. australis with regard to the steroidogenic activity reported in other seal species.

Sistematização e distribuição da inervação lombar e sacral em Arctocephalus australis / The lumbar and sacral innervation of the Arctocephalus australis: sistematization and distribution

Objetivando descrever a inervação originada a partir dos ramos ventrais lombares e sacrais, fez-se um estudo, mediante a dissecação de dois exemplares de lobos-marinhos (Arctocephalus australis), oriundos do CRAM-FURG, onde chegaram em óbito. As estruturas nervosas constituintes dos plexos lombar e sacral possuem origem dos ramos ventrais dos nervos espinhais que formam-se dos segmentos medulares L1 a S3. Assim, pode-se observar que, os formados dos segmentos L1 a L3 são unissegmentares, sendo respectivamente os nervos Ílio-hipogástrico e Ílio-inguinal e Cutâneo Femoral Lateral. Da união dos segmentos L3-L4 surgem os nervos Genito-femoral, Obturatório e Femoral. Da confluência dos segmentos L4-5-S1 forma-se um tronco nervoso, o plexo isquiático, que emite os nervos: Glúteos Cranial e Caudal, Cutâneo Femoral Caudal e Isquiático. O nervo Isquiático ramifica-se em Cutâneos Surais Lateral e Caudal, Tibial, Fibular Comum. O nervo Pudendo (divide-se nos nervos dorsal do pênis ou clitóris e perineais superficial e profundo) e Retal Caudal têm origem dos segmentos S2-3. Com base nestes dados podemos inferir que a inervação lombar e sacral têm origem similar a outras espécies de mamíferos, contudo sua organização e distribuição refletem as modificações adaptativas aos hábitos destes animais, principalmente a locomoção em meio aquático.

In order to describe the innervation originated from ventral lumbar and sacral branches, a study was made through dissection of two specimens of south american fur seals (Arctocephalus australis), originated from CRAM-FURG, where they arrived deceased. The nervous structures that constitute the lumbar and sacral plexes are originated from ventral branches of spinal nerves which come from medullary segments L1 to S3. Thus, one can observe that the nerves originated form L1 to L3 are monosegmentary, being respectively iliohypogastric, ilioinguinal and lateral femoral cutaneous nerves. From the reunion of L3 and L4 segments arise genitofemoral, obturator and femoral nerves. From the confluence of segments L4-5-S1 arises a nervous trunk – the sciatic plexus, which gives the following nerves: cranial and caudal gluteal, caudal femoral cutaneous and sciatic. Sciatic nerve splits into lateral and caudal sural cutaneous, tibial, common peroneal. Pudendal nerve (which divides into dorsal nerve of the penis or clitoris, deep and superficial perineal) and caudal rectal are formed from the S2-3 segments. With these data, one can conclude that the lumbar and sacral innervation have similar origin to other mammal species, however its organization and distribution reflect the adaptative changes to this animals’ habits, specially its locomotionin water.

Sistematização e distribuição da inervação lombar e sacral em Arctocephalus australis / The lumbar and sacral innervation of the Arctocephalus australis: sistematization and distribution

Objetivando descrever a inervação originada a partir dos ramos ventrais lombares e sacrais, fez-se um estudo, mediante a dissecação de dois exemplares de lobos-marinhos (Arctocephalus australis), oriundos do CRAM-FURG, onde chegaram em óbito. As estruturas nervosas constituintes dos plexos lombar e sacral possuem origem dos ramos ventrais dos nervos espinhais que formam-se dos segmentos medulares L1 a S3. Assim, pode-se observar que, os formados dos segmentos L1 a L3 são unissegmentares, sendo respectivamente os nervos Ílio-hipogástrico e Ílio-inguinal e Cutâneo Femoral Lateral. Da união dos segmentos L3-L4 surgem os nervos Genito-femoral, Obturatório e Femoral. Da confluência dos segmentos L4-5-S1 forma-se um tronco nervoso, o plexo isquiático, que emite os nervos: Glúteos Cranial e Caudal, Cutâneo Femoral Caudal e Isquiático. O nervo Isquiático ramifica-se em Cutâneos Surais Lateral e Caudal, Tibial, Fibular Comum. O nervo Pudendo (divide-se nos nervos dorsal do pênis ou clitóris e perineais superficial e profundo) e Retal Caudal têm origem dos segmentos S2-3. Com base nestes dados podemos inferir que a inervação lombar e sacral têm origem similar a outras espécies de mamíferos, contudo sua organização e distribuição refletem as modificações adaptativas aos hábitos destes animais, principalmente a locomoção em meio aquático.(AU)

In order to describe the innervation originated from ventral lumbar and sacral branches, a study was made through dissection of two specimens of south american fur seals (Arctocephalus australis), originated from CRAM-FURG, where they arrived deceased. The nervous structures that constitute the lumbar and sacral plexes are originated from ventral branches of spinal nerves which come from medullary segments L1 to S3. Thus, one can observe that the nerves originated form L1 to L3 are monosegmentary, being respectively iliohypogastric, ilioinguinal and lateral femoral cutaneous nerves. From the reunion of L3 and L4 segments arise genitofemoral, obturator and femoral nerves. From the confluence of segments L4-5-S1 arises a nervous trunk the sciatic plexus, which gives the following nerves: cranial and caudal gluteal, caudal femoral cutaneous and sciatic. Sciatic nerve splits into lateral and caudal sural cutaneous, tibial, common peroneal. Pudendal nerve (which divides into dorsal nerve of the penis or clitoris, deep and superficial perineal) and caudal rectal are formed from the S2-3 segments. With these data, one can conclude that the lumbar and sacral innervation have similar origin to other mammal species, however its organization and distribution reflect the adaptative changes to this animals habits, specially its locomotion in water.(AU)

Gross heart anatomy of Arctocephalus australis (Zimmerman, 1783).

Little research has been carried out on the gross visceral anatomy of the Otariidae, and the anatomical information for the southern fur seals, Arctocephalus spp., is scant. The aim of the present study was to describe the external and internal conformation, and the sanguineous irrigation of the heart of Arctocephalus australis. Twelve hearts of Arctocephalus australis were studied by simple dissection. In the right ventricle the trabeculae carneae were well developed and there were three or more papillary muscles. In the left ventricle there were two papillary muscles, subatrialis and subauricularis, attached to the parietal wall. There was also a great development of trabeculae carneae which occupied almost all of the ventricle, from the left atrioventricular valve up to the proximities of the expulsion route. A large quantity of muscular strands were found extending themselves between the trabeculae carneae, becoming more dense and forming a network when near the apex. The distribution of the branches of the coronary arteries was highly variable and no heart was similar to another one in this sense. In the majority of the hearts the subsinosal interventricular branch proceeded from the right coronary artery. It is concluded that there were many differences between the heart of the Arctocephalus australis and the heart of the domestic dog, contrary to what has been suggested for other genera of Otariidae.