E.The role of positive and negative signals in somite
The following somatic parts of each crab were measured: maximum carapace width (CW; was always measured behind the third cephalothoracic spine), abdomen width for females (AW; obtained from the 5 th to 6th abdominal somite
) and gonopod length for males (GL) to the nearest 0.1 mm using a Vernier caliper.
First leg-bearing somite
separates from cephalosome.
Closure of cranial neuropore occurs at about 25th day (8-20 somite
stage) whereas the posterior neuropore closes at about 28th day (25 somite
GFP expression in somite
muscle was more intense in anterior somites
than in posterior somites
at early larval stages, but posterior expression increased gradually over time in later larval stages.
Many significant studies about somite
fate were performed using the quail-chick cross-transplantation technique, and somite
cross-transplantation has been employed to describe the origin of the brachial muscles (Beresford, 1983), identify a population of cells within the somite
that give rise to the muscles of the back and a second population of cells that give rise to the limb musculature (Ordahl and Le Douarin, 1992), and the fate of the first somite
(Huang et al., 1997).
A faint rectangular area is located on the eighth thoracic somite
. No habitat data other than depth were given with the specimens I examined.
5, A and K): Abdomen six-segmented; dorsomedian spines on posterior margin of the 1st-5th abdominal somites
; one pair of spines on posterolateral margins of 5th and 6th abdominal somites
; 6th abdominal somite
also with one pair of spines on lateroventral margin; pereiopods appeared.
Lassar, "Asymmetric localization of numb in the chick somite
and the influence of myogenic signals," Developmental Dynamics, vol.
Abdomen of six somites
, and telson free articulated, widest at third segment, which represents almost 3A of entire length; gradually narrowing from third somite
to telson, which is obtusely rounded.
Male crabs have a thin and narrow abdomen and a pair of long thin pleopods (gonopods) on the ventral surface of the first abdominal somite
. Female crabs have large and wide abdomens and four pairs of long setose pleopods from the second to the fifth abdominal somites
Tissues such as the liver, forebrain, lateral line (a sensory system found in aquatic vertebrates), otic vesicles, eyes, heart, and cranial and somite
muscle appeared to be strongly affected by some of the compounds tested, but not others.