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Zoomorphology

, Volume 105, Issue 4, pp 253–264 | Cite as

Development of the pedicle in the articulate brachiopod Terebratalia transversa (Brachiopoda, Terebratulida)

  • Stephen A. Stricker
  • Christopher G. Reed
Article

Summary

The development of the pedicle in the articulate brachiopod Terebratalia transversa has been examined by electron microscopy. The posterior half of the free-swimming larva comprises a non-ciliated pedicle lobe that contains the primordium of the juvenile pedicle at its distal end. During settlement at five to six days post-fertilization, the pedicle lobe secretes a sticky sheet that attaches the larva to the substratum. As metamorphosis proceeds, the epithelium in the posterior half of the pedicle lobe produces a thin overlying cuticle, and the pedicle primordium develops into a stalk-like anchoring organ. The juvenile pedicle protrudes through the gape that occurs between the posterior margins of the shell valves. A cup-like canopy, called the pedicle capsule, lines the posterior end of the shell and surrounds the newly formed pedicle. The core of the juvenile pedicle is filled with a solid mass of connective tissue. Numerous tonofibrils occur in the pedicle epithelium, and the overlying cuticle consists of amorphous material covered by a thin granular fringe. By one year post-metamorphosis, a body cavity develops anterior to the pedicle. Two pairs of adjustor muscles extend from the posterior end of the shell and traverse the cavity to insert in the pedicle. The connective tissue core of the pedicle in sub-adult specimens lacks muscle cells but contains numerous fibroblasts and collagen fibers. Three regions are recognizable in the connective tissue compartment of the adult pedicle: a subepithelial layer of non-fibrous connective tissue, a central fibrous zone, and a proximal mass of tissue that resembles cartilage.

Keywords

Connective Tissue Posterior Margin Tissue Core Body Cavity Tissue Compartment 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of abbreviations

as

adhesive sheet

bc

body cavity

bv

brachial valve of shell

cf

collagen fibrils

ct

connective tissue

cu

cuticle

di

diductor muscle

ec

epithelial cell

f

fibroblast

fz

fibrous zone

g

gut

gc

granular cell

gd

gastric diverticulum

ht

hinge tooth

ia

interarea of pedicle valve

icl

inner cuticular layer

lo

lophophore

lu

lumen of gut

m

mesenchyme

ma

mantle

ml

mantle lobe

ocl

outer cuticular layer

p

periostracum

pc

pedicle capsule

pce

pedicle capsule epithelium

pcl

pedicle collar of shell

pcn

pedicle connectives

pd

pedicle

pe

pedicle epithelium

pl

pedicle lobe

pv

pedicle valve of shell

pzc

proximal zone of cartilage-like tissue

s

substratum

sel

subepithelial layer

t

tendon

tf

tonofibril

vam

ventral adjustor muscle

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Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • Stephen A. Stricker
    • 1
  • Christopher G. Reed
    • 2
  1. 1.Department of BiologyUniversity of CalgaryCalgaryCanada
  2. 2.Department of Biological SciencesDartmouth CollegeHanoverUSA

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