294
spicules (Montes et al. 1982 ; Becerra et al. 1996 ). According to Géraudie and
Landis ( 1982 ), the actinotrichia are “rods of elastoidin that occupy the distal margin
of the fi n and precede the differentiation of lepidotrichia. Once the lepidotrichia
form, actinotrichia lie preferentially between their demirays. In some instances,
structural interactions are suggested between actinotrichia and lepidotrichia,”
(Géraudie and Landis 1982 ). Actinotrichia serving as a scaffold for the migration
into the fi n fold of the mesenchymal cells that will form the future fi n connective
tissue (Wood 1982 ; Wood and Thorogood 1984 ). Actinotrichia are localized within
a loose connective tissue with blood vessels and nerves, and surrounded by a stratifi ed
epidermis (Becerra et al. 1983 ). They are synthesized by the so-called actinotrichia
forming cells (AFC), whose exact identity and origin (epidermal or mesenchymal)
is still unknown (Durán et al. 2011 ). It is suggested that actinotrichia fulfi l following
functions:
– a morphogenetic role in lepidotrichia morphogenesis, possibly by inducing
differentiation of scleroblasts or lepidotrichia forming cells (LFC) (Santamaría
and Becerra 1991 );
– actinotrichia might be responsible for maintaining the structural integrity of the
early fi n fold (Dane and Tucker 1985 );
– loss of actinotrichia during evolution may have led to loss of lepidotrichia and
contributed to the fi n-to-limb transition (Zhang et al. 2010 ).
From a biological materials point of view, both the chemistry and structural
biology of actinotrichia as unique fi brillar collagen-containing composites are very
interesting (Fig. 7.8 ). Collagen-related aspects of these structures are well described
in the work of Duran et al. ( 2011 ) as follow:
Fig. 7.8 TEM image
(Adapted from Böckelmann
and Bechara 2009 ). Observe
the longitudinal section of the
actinotrichium and the
regular transversal striation
characteristic of collagen
proteins (Reprinted from
Böckelmann and Bechara
( 2009 ) with permission)
7 Fish Fins and Rays as Inspiration for Materials Engineering and Robotics
spicules (Montes et al. 1982 ; Becerra et al. 1996 ). According to Géraudie and
Landis ( 1982 ), the actinotrichia are “rods of elastoidin that occupy the distal margin
of the fi n and precede the differentiation of lepidotrichia. Once the lepidotrichia
form, actinotrichia lie preferentially between their demirays. In some instances,
structural interactions are suggested between actinotrichia and lepidotrichia,”
(Géraudie and Landis 1982 ). Actinotrichia serving as a scaffold for the migration
into the fi n fold of the mesenchymal cells that will form the future fi n connective
tissue (Wood 1982 ; Wood and Thorogood 1984 ). Actinotrichia are localized within
a loose connective tissue with blood vessels and nerves, and surrounded by a stratifi ed
epidermis (Becerra et al. 1983 ). They are synthesized by the so-called actinotrichia
forming cells (AFC), whose exact identity and origin (epidermal or mesenchymal)
is still unknown (Durán et al. 2011 ). It is suggested that actinotrichia fulfi l following
functions:
– a morphogenetic role in lepidotrichia morphogenesis, possibly by inducing
differentiation of scleroblasts or lepidotrichia forming cells (LFC) (Santamaría
and Becerra 1991 );
– actinotrichia might be responsible for maintaining the structural integrity of the
early fi n fold (Dane and Tucker 1985 );
– loss of actinotrichia during evolution may have led to loss of lepidotrichia and
contributed to the fi n-to-limb transition (Zhang et al. 2010 ).
From a biological materials point of view, both the chemistry and structural
biology of actinotrichia as unique fi brillar collagen-containing composites are very
interesting (Fig. 7.8 ). Collagen-related aspects of these structures are well described
in the work of Duran et al. ( 2011 ) as follow:
Fig. 7.8 TEM image
(Adapted from Böckelmann
and Bechara 2009 ). Observe
the longitudinal section of the
actinotrichium and the
regular transversal striation
characteristic of collagen
proteins (Reprinted from
Böckelmann and Bechara
( 2009 ) with permission)
7 Fish Fins and Rays as Inspiration for Materials Engineering and Robotics