ISSN:
0362-2525
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
The tubules vary in number from about 190 to 300. They gather into twelve groups each consisting of an anterior and a posterior division and each emptying into one of twelve ampullae arranged equi-distant from each other about the wall of the posterior mid-gut and in a transverse plane just anterior to the sphincter muscle which marks, externally, the junction of mid- and hind-gut, that is to say, the ‘pyloric valve.’ The lumen of each ampulla is continuous with one of twelve furrows formed by the gathering of the hindgut epithelium into as many folds.The wall of the digestive tube is made up of, (1) an inner epithelium (tall columnar cells), (2) an intermediate connective tissue layer, and (3) an outer muscular coat (inner circular and outer longitudinal layer). The mid-gut epithelium dips down at frequent intervals to form crypts at the bases of which are the ‘regeneration centers.’ This epithelium is covered, on its luminar surface, by a curious striated border. The epithelium of the hind-gut appears to be covered by chitin.A malpighian tubule consists of a single layer of large polygonal cells with indistinct borders. It is covered externally by a thin membrene made up of ‘peritoneal cells’ and internally by a striated border similar to that in the mid-gut. Spiralling about each tubule from origin (free end) to insertion (in the gut) is a slender tracheole.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jmor.1050580107
