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A cytologic analysis of the bag cell control of egg laying in Aplysia
Author(s) -
Coggeshall Richard E.
Publication year - 1970
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1051320407
Subject(s) - ovotestis , biology , endoplasmic reticulum , microbiology and biotechnology , yolk , contraction (grammar) , oocyte , anatomy , embryo , endocrinology , gonad , ecology
A fine structural analysis of the ovotestis in Aplysia was undertaken in order to analyze the site of action of the bag cell hormone. Five stages of oocyte development are described. Of particular interest is the fact that the yolk seems to be synthesized primarily by the granular endoplasmic reticulum. In addition, small muscle cells whose long, thin processes surround the follicle of the ovotestis have been pointed out. This paper suggests that bag cell extract has a direct action on these small muscle cells causing them to contract and thus expel oocytes from the ovotestis. The evidence for this suggestion is that (1) these muscle cells are the most obvious effector cells in the ovotestis, (2) there are no signs of neural innervation of these muscles, (3) the time course for the liberation of the oocytes is so short that any other method of oocyte release is unlikely, (4) there is no cytologic evidence for any other expulsion process except muscular contraction, and (5) the ripe oocytes are attached to other cells of the wall of the ovotestis only by very small, simple junctions, thus making them the most likely cells to be expelled by muscular contraction.