Fig 7 - uploaded by Alfredo Armando Carlini
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Leptonychotes weddellii. Outer era canal (OEC), middle (A, B, C) and proximal regions (D, E, F), transversal section. A-reconstruction of the middle OEC in general view (4x, Gomori trichrome stain), B-panoramic view of the epidermis-dermis (H-E stain), C-detail of the cartilage with myxoid tissue (Giemsa), D-reconstruction of the proximal OEC in general view (4x, Gomori trichrome stain), E-panoramic view of the epidermis-dermis, F-detail of the elastic cartilage (orcein stain). Abbreviations: (ad) adipose tissue, (ca) cartilage, (dde) deep dermis, (ep) epidermis, (hf) hair follicles, (mf) muscular fibres, (mt) myxoid tissue, (sbg) sebaceous glands, (sde) superficial dermis.
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A B S T R A C T
Pinnipeds are semiaquatic carnivorans that spend most of their lives in water and use coastal terrestrial, or ice
pack, environments to breed, molt and rest. Certain characteristics of the ear have been linked to ecological aspects.
In our contribution we focus on the study of the macroscopic and microscopic morphology of the extern...
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... middle region shows a lumen similar to that of M. leonina (Fig. 7A, B). The dermis is thinner than in the distal region (Fig. 7B). The hair follicles are arranged in groups similar to those of the distal region, although fewer (Fig. 7B). The sebaceous glands are more developed than in the distal region and ceruminous glands are scarcer (Fig. 7B). Underlying the dermis, the hypodermis is well developed in ...
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... middle region shows a lumen similar to that of M. leonina (Fig. 7A, B). The dermis is thinner than in the distal region (Fig. 7B). The hair follicles are arranged in groups similar to those of the distal region, although fewer (Fig. 7B). The sebaceous glands are more developed than in the distal region and ceruminous glands are scarcer (Fig. 7B). Underlying the dermis, the hypodermis is well developed in the free-cartilage zones, while in zones with cartilage the ...
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... middle region shows a lumen similar to that of M. leonina (Fig. 7A, B). The dermis is thinner than in the distal region (Fig. 7B). The hair follicles are arranged in groups similar to those of the distal region, although fewer (Fig. 7B). The sebaceous glands are more developed than in the distal region and ceruminous glands are scarcer (Fig. 7B). Underlying the dermis, the hypodermis is well developed in the free-cartilage zones, while in zones with cartilage the hypodermis lies externally to it. The cartilage (Fig. 7C) in this region shows some special features: in ...
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... middle region shows a lumen similar to that of M. leonina (Fig. 7A, B). The dermis is thinner than in the distal region (Fig. 7B). The hair follicles are arranged in groups similar to those of the distal region, although fewer (Fig. 7B). The sebaceous glands are more developed than in the distal region and ceruminous glands are scarcer (Fig. 7B). Underlying the dermis, the hypodermis is well developed in the free-cartilage zones, while in zones with cartilage the hypodermis lies externally to it. The cartilage (Fig. 7C) in this region shows some special features: in some parts it is typical elastic cartilage, while in other parts the cells appear less ordered, and resemble ...
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... similar to those of the distal region, although fewer (Fig. 7B). The sebaceous glands are more developed than in the distal region and ceruminous glands are scarcer (Fig. 7B). Underlying the dermis, the hypodermis is well developed in the free-cartilage zones, while in zones with cartilage the hypodermis lies externally to it. The cartilage (Fig. 7C) in this region shows some special features: in some parts it is typical elastic cartilage, while in other parts the cells appear less ordered, and resemble myxoid tissue. In the latter portion, the matrix is positive for Alcian 2.5 and Giemsa, and shows scarce thin reticular fibers. In addition, unilocular adipocytes are present, ...
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... lumen in the proximal region is not collapsed (Fig. 7D). The epidermis is thin, similar to that of the middle region. The dermis is more vascularized than in the other regions (Fig. 7E). There are fewer hair follicles than in the previous regions, the sebaceous glands are well developed (Fig. 7E), and ceruminous glands are also observed. The elastic cartilage shows myxoid-like tissue, ...
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... lumen in the proximal region is not collapsed (Fig. 7D). The epidermis is thin, similar to that of the middle region. The dermis is more vascularized than in the other regions (Fig. 7E). There are fewer hair follicles than in the previous regions, the sebaceous glands are well developed (Fig. 7E), and ceruminous glands are also observed. The elastic cartilage shows myxoid-like tissue, similar to the middle region (Fig. ...
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... lumen in the proximal region is not collapsed (Fig. 7D). The epidermis is thin, similar to that of the middle region. The dermis is more vascularized than in the other regions (Fig. 7E). There are fewer hair follicles than in the previous regions, the sebaceous glands are well developed (Fig. 7E), and ceruminous glands are also observed. The elastic cartilage shows myxoid-like tissue, similar to the middle region (Fig. ...
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... is thin, similar to that of the middle region. The dermis is more vascularized than in the other regions (Fig. 7E). There are fewer hair follicles than in the previous regions, the sebaceous glands are well developed (Fig. 7E), and ceruminous glands are also observed. The elastic cartilage shows myxoid-like tissue, similar to the middle region (Fig. ...
Citations
... This mosaic functional profile of the middle ear is also observed in phocids (figure 2; electronic supplementary material, figure S9) that are able to hear efficiently in both aquatic and aerial soundtopes [72][73][74][75][76][77][78]. Although phocids and UM-KPG-M 73 present different morphological adaptations towards amphibious hearing (such as a strong increase in incudal mass for the former [69] and a potential double sound input area for the latter), their middle ears' functional profiles are very similar. ...
Modifications of the morphology and acoustic properties of the ossicular chain are among the major changes that accompanied the adaptation of Cetacea to the aquatic environment. Thus, data on the middle ear ossicles of early whales are crucial clues to understand the first steps of the emblematic terrestrial/aquatic transition that occurred in that group. Yet, the delicate nature and very small size of these bones make their preservation in the fossil record extremely rare. Due to the scarcity of available data, major questions remain concerning the sound transmission pathways in early non-fully aquatic whales. Virtual reconstruction of a partially complete ossicular chain of an Eocene protocetid whale documents for the first time the three ossicles of a semi-aquatic archaeocete. Contrary to previous hypotheses, these ossicles present different evolutionary patterns, showing that the ossicular chain does not act as a single morphological module. Functional analyses of the different middle ear units highlight a mosaic pattern of terrestrial and aquatic signatures. This integrative anatomical and functional study brings strong evidence that protocetids were adapted to their dual acoustic environment with efficient hearing in both air and water.
